Telmisartan

What it is

Telmisartan is a synthetic small-molecule angiotensin II receptor blocker taken as a tablet once a day. It binds the AT1 receptor and blocks the actions of angiotensin II, the main pressure-raising hormone of the renin-angiotensin system. It is unusual among blood-pressure drugs in being cleared almost entirely unchanged in the bile rather than metabolised by cytochrome P450 enzymes, and it has a long elimination half-life of about 24 hours.

What the research says

The evidence is strongest for what telmisartan does to blood pressure: placebo-controlled trials show falls of roughly 6 to 13 mmHg systolic depending on dose. For hard outcomes the picture is more mixed. In a 25,620-patient trial against the ACE inhibitor ramipril it was equivalent, with less cough and less angioedema. In a 5,926-patient placebo-controlled trial in people who could not tolerate ACE inhibitors it missed its primary endpoint, and in a 20,332-patient trial started soon after a stroke it did not reduce recurrent stroke. Its main harms are low blood pressure, raised potassium, worsened kidney function when combined with another renin-angiotensin blocker, and serious injury to a fetus.

Evidence grade: Well established.

How it works

Drug class: Angiotensin II receptor blocker (ARB; angiotensin II type-1 receptor antagonist)

Angiotensin II narrows blood vessels, triggers aldosterone release and makes the kidney hold on to sodium. Telmisartan sits on the AT1 receptor where angiotensin II would normally act, so the hormone cannot produce those effects, and blood vessels relax. Because it blocks the receptor rather than the enzyme that makes angiotensin II, it does not interfere with bradykinin breakdown, which is the reason ACE inhibitors cause cough. (Source 1)

Boxed warning

When pregnancy is detected, discontinue telmisartan as soon as possible [see Warnings and Precautions (5.1)and Use in Specific Populations (8.1)].

(Source 2)

What it is used for

• Six placebo-controlled trials in 1,773 people with mild to moderate hypertension showed placebo-subtracted falls of about 6-8/6 mmHg at 20 mg and 12-13/7-8 mmHg at 80 mg. The label itself states that no telmisartan trial has shown reduced cardiovascular risk in people with hypertension. Evidence: established. (Source 3)
• ONTARGET found telmisartan equivalent to ramipril, but TRANSCEND, the placebo-controlled trial in exactly the approved population, missed its primary endpoint (15.7% vs 17.0%, HR 0.92, p=0.216). The approval rests on a secondary endpoint that lost statistical significance after adjustment for multiplicity. Evidence: disputed. (Source 4)
• In 20,332 people randomised a median of 15 days after an ischaemic stroke, telmisartan did not significantly reduce recurrent stroke over 2.5 years (8.7% vs 9.2%, HR 0.95, p=0.23). Evidence: not-supported. (Source 5)
• A 2026 meta-analysis of six randomised trials in 258 people found no significant change in BMI, waist circumference, HOMA-IR, lipids, ALT or AST, and a small significant rise in GGT. One small 1-year trial reported histological improvement, but the pooled evidence does not support a benefit. Evidence: not-supported. (Source 6)

Interactions

• Potassium supplements and potassium-containing salt substitutes (label): Both can push blood potassium higher on top of the rise telmisartan itself causes. The label tells patients not to use them without asking the prescriber first. (Source 7)
• Potassium-sparing diuretics and other drugs that raise potassium (label): Adding them to telmisartan raises the chance of a dangerously high potassium level, particularly in advanced kidney disease or heart failure. (Source 8)
• Food (pharmacokinetic study): Food slightly reduces how much telmisartan is absorbed, by about 6% at 40 mg and about 20% at 160 mg. The label allows it to be taken with or without food. (Source 9)
• Grapefruit juice and other CYP3A4-dependent interactions (pharmacokinetic study): Telmisartan is not metabolised by cytochrome P450 enzymes, so the grapefruit interaction that affects many other drugs is not expected. The label documents no grapefruit interaction. (Source 10)
• Digoxin (pharmacokinetic study): Telmisartan raises digoxin blood levels, so digoxin levels need checking when telmisartan is started, changed or stopped. (Source 11)
• Lithium (case reports): Lithium levels can rise and lithium toxicity has been reported when it is taken with telmisartan or other ARBs. (Source 11)
• NSAIDs, including ibuprofen and selective COX-2 inhibitors (label): In older people, people who are volume-depleted or those with reduced kidney function, combining an NSAID with telmisartan can worsen kidney function, sometimes to acute kidney failure, and can blunt the blood-pressure effect. (Source 11)
• Aliskiren (label): Combining telmisartan with the renin inhibitor aliskiren is contraindicated in people with diabetes and should be avoided in kidney impairment. (Source 11)
• ACE inhibitors such as ramipril (dual renin-angiotensin blockade) (clinical trial): Using two renin-angiotensin blockers together raises the risk of low blood pressure, high potassium and kidney failure without adding benefit. (Source 12)

Stopping it

• After telmisartan is stopped, blood pressure drifts back to its untreated level over several days to about a week. The label describes no withdrawal syndrome or rebound overshoot. (Source 3)
• The boxed warning directs that telmisartan be stopped as soon as a pregnancy is detected, because of injury and death to the developing fetus. (Source 2)
• In the two large outcome trials, more people stopped placebo than stopped telmisartan, which argues against telmisartan being difficult to stay on: 21.6% versus 23.8% permanently discontinued in TRANSCEND, with hypotensive symptoms the commonest reason. (Source 13)

What goes wrong

Adding telmisartan to ramipril produced no extra benefit and more harm, including more kidney dysfunction. (Source 4)

• Randomized trial, High certainty.
• Size: 8,502 on combination vs 8,576 on ramipril.
• Who: As above.
• How long: Median 56 months.
• Result: Primary outcome 16.3% on combination (relative risk 0.99; 95% CI 0.92 to 1.07); hypotensive symptoms 4.8% vs 1.7% (P<0.001), syncope 0.3% vs 0.2% (P=0.03), renal dysfunction 13.5% vs 10.2% (P<0.001)
• Funding: not stated in the abstract.

In the combination-therapy group, the primary outcome occurred in 1386 patients (16.3%; relative risk, 0.99; 95% CI, 0.92 to 1.07); as compared with the ramipril group, there was an increased risk of hypotensive symptoms (4.8% vs. 1.7%, P<0.001), syncope (0.3% vs. 0.2%, P=0.03), and renal dysfunction (13.5% vs. 10.2%, P<0.001)

Telmisartan can raise blood potassium, especially in advanced kidney disease, heart failure, or when combined with potassium supplements, potassium-sparing diuretics or potassium-containing salt substitutes. (Source 8)

• Official position, Low certainty.
• Size: not quantified in the label.
• Who: People on ARBs, particularly with advanced renal impairment, heart failure or on potassium supplements.
• How long: ongoing treatment.
• Result: No rate is given; the label advises periodic electrolyte measurement.
• Funding: not applicable (regulatory position)

Hyperkalemia may occur in patients on ARBs, particularly in patients with advanced renal impairment, heart failure, on renal replacement therapy, or on potassium supplements, potassium-sparing diuretics, potassium-containing salt substitutes or other drugs that increase potassium levels. Consider periodic determinations of serum electrolytes to detect possible electrolyte imbalances, particularly in patients at risk.

Drugs acting on the renin-angiotensin system reduce fetal kidney function in the second and third trimesters and increase fetal and neonatal illness and death. (Source 14)

• Official position, Moderate certainty.
• Size: not quantified.
• Who: Pregnant women and their fetuses.
• How long: second and third trimesters.
• Result: Oligohydramnios, fetal lung hypoplasia, skeletal deformations, skull hypoplasia, anuria, hypotension, renal failure and death; no numeric rate is given.
• Funding: not applicable (regulatory position; this is the boxed warning subject)

Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death.

A meta-analysis of randomised trials, in which telmisartan accounted for 85.7% of ARB exposure, reported a modest excess of new cancer diagnoses on ARBs. (Source 15)

• Meta-analysis, Low certainty.
• Size: 61,590 participants from five trials for new cancers; 93,515 from eight trials for cancer deaths.
• Who: Participants in randomised ARB trials, mostly cardiovascular risk populations.
• How long: at least 1 year of follow-up per trial.
• Result: New cancer 7.2% vs 6.0%, risk ratio 1.08, 95% CI 1.01-1.15, p=0.016; lung cancer 0.9% vs 0.7%, RR 1.25, 1.05-1.49, p=0.01; cancer deaths 1.8% vs 1.6%, RR 1.07, 0.97-1.18, p=0.183 (not significant)
• Funding: not stated.

Limit of this finding: This is a trial-level meta-analysis, not a study of telmisartan: the authors state that given the limited data it is not possible to draw conclusions about the risk of cancer associated with any particular drug. The 85.7% is telmisartan's share of the patients allocated to an ARB in the trials contributing new-cancer data, not of all 61,590 participants. The excess was small (7.2% against 6.0%) and cancer deaths were not significantly different. The much larger ARB Trialists Collaboration analysis found no excess at all.

Patients randomly assigned to receive ARBs had a significantly increased risk of new cancer occurrence compared with patients in control groups (7.2%vs 6.0%, risk ratio [RR] 1.08, 95% CI 1.01-1.15; p=0.016). When analysis was limited to trials where cancer was a prespecified endpoint, the RR was 1.11 (95% CI 1.04-1.18, p=0.001). Among specific solid organ cancers examined, only new lung-cancer occurrence was significantly higher in patients randomly assigned to receive ARBs than in those assigned to receive control (0.9%vs 0.7%, RR 1.25, 1.05-1.49; p=0.01). No statistically significant difference in cancer deaths was observed (1.8%vs 1.6%, RR 1.07, 0.97-1.18; p=0.183)

What the evidence supports

In 25,620 people with vascular disease or high-risk diabetes, telmisartan 80 mg was equivalent to ramipril 10 mg for the composite of cardiovascular death, myocardial infarction, stroke or hospitalisation for heart failure. (Source 4)

• Randomized trial, High certainty.
• Size: 25,620 participants (8,542 telmisartan, 8,576 ramipril, 8,502 combination)
• Who: People with vascular disease or high-risk diabetes without heart failure, mean age over 65 in 57%.
• How long: Median 56 months.
• Result: Primary outcome 16.7% with telmisartan vs 16.5% with ramipril; relative risk 1.01, 95% CI 0.94 to 1.09. Mean blood pressure was 0.9/0.6 mmHg lower on telmisartan.
• Funding: not stated in the abstract; the trial was sponsored by Boehringer Ingelheim.

At a median follow-up of 56 months, the primary outcome had occurred in 1412 patients in the ramipril group (16.5%), as compared with 1423 patients in the telmisartan group (16.7%; relative risk, 1.01; 95% confidence interval [CI], 0.94 to 1.09)

Telmisartan lowers blood pressure in a dose-related way across 20 to 80 mg, with no further fall at higher doses. (Source 3)

• Official position, Moderate certainty.
• Size: 1,773 participants across six principal placebo-controlled trials, 1,031 on telmisartan.
• Who: Adults with mild to moderate hypertension (diastolic 95 to 114 mmHg)
• How long: Maximal reduction by about 4 weeks; long-term studies up to at least one year.
• Result: Placebo-subtracted systolic/diastolic reduction approximately 6-8/6 mmHg for 20 mg, 9-13/6-8 mmHg for 40 mg and 12-13/7-8 mmHg for 80 mg; doses up to 160 mg gave no further fall.
• Funding: not stated (FDA-approved labelling summarising sponsor trials)

Following once daily administration of telmisartan, the magnitude of blood pressure reduction from baseline after placebo subtraction was approximately (SBP/DBP) 6-8/6 mmHg for 20 mg, 9-13/6-8 mmHg for 40 mg, and 12-13/7-8 mmHg for 80 mg. Larger doses (up to 160 mg) did not appear to cause a further decrease in blood pressure.

Blood pressure returns to baseline within days to about a week after telmisartan is stopped, with no evidence of rebound reported in the label. (Source 3)

• Official position, Low certainty.
• Size: not stated.
• Who: Adults in the label's long-term hypertension studies.
• How long: several days to one week after cessation.
• Result: Gradual return to baseline values over several days to one week.
• Funding: not applicable (regulatory position)

With cessation of treatment with telmisartan tablets, blood pressure gradually returned to baseline values over a period of several days to one week.

In short placebo-controlled trials the overall rate of adverse events on telmisartan was similar to placebo, and fewer people stopped telmisartan than placebo. (Source 16)

• Official position, Low certainty.
• Size: 1,041 patients on telmisartan monotherapy in placebo-controlled trials; 1,455 vs 380 for the adverse-event table.
• Who: Adults with hypertension.
• How long: Up to 12 weeks.
• Result: Upper respiratory tract infection 7% vs 6%, back pain 3% vs 1%, sinusitis 3% vs 2%, diarrhoea 3% vs 2%, pharyngitis 1% vs 0%. Discontinuation for adverse events 2.8% of 1,455 on telmisartan vs 6.1% of 380 on placebo. Cough 1.6% in both groups.
• Funding: not applicable (regulatory position summarising sponsor trials)

Limit of this finding: The label gives two different denominators in the same passage and never reconciles them. Its opening sentence says the adverse-event comparison covers 1041 patients given telmisartan, while the table beside it and the discontinuation sentence that follows both count 1455 patients on telmisartan against 380 on placebo. The inconsistency is the label's own. What a reader can take from it is the individual rates as printed - for example upper respiratory tract infection 7% against 6% - and the fact that fewer people stopped telmisartan than stopped placebo. What a reader cannot do is treat 1041 and 1455 as the same group, work out how many people had a given event, or conclude anything about how large or precise these differences are.

In placebo-controlled trials involving 1041 patients treated with various doses of telmisartan (20 to 160 mg) monotherapy for up to 12 weeks, the overall incidence of adverse events was similar to that in patients treated with placebo. Adverse events occurring at an incidence of ≥1% in patients treated with telmisartan and at a greater rate than in patients treated with placebo, irrespective of their causal association, are presented in Table 1. Table 1 Adverse Events Occurring at an Incidence of ≥1% in Patients Treated with Telmisartan and at a Greater Rate Than Patients Treated with Placebo | | Telmisartan n=1455 % | Placebo n=380 % | | Upper respiratory tract infection | 7 | 6 | | Back pain | 3 | 1 | | Sinusitis | 3 | 2 | | Diarrhea | 3 | 2 | | Pharyngitis | 1 | 0 | In addition to the adverse events in the table, the following events occurred at a rate of ≥1% but were at least as frequent in the placebo group: influenza-like symptoms, dyspepsia, myalgia, urinary tract infection, abdominal pain, headache, dizziness, pain, fatigue, coughing, hypertension, chest pain, nausea, and peripheral edema. Discontinuation of therapy because of adverse events was required in 2.8% of 1455 patients treated with telmisartan tablets and 6.1% of 380 placebo patients in placebo-controlled clinical trials.

What the evidence does not support

In the population telmisartan is actually approved for - people at high cardiovascular risk who cannot tolerate ACE inhibitors - the placebo-controlled trial missed its primary endpoint. (Source 13)

• Randomized trial, High certainty.
• Size: 5,926 participants (2,954 telmisartan, 2,972 placebo)
• Who: People intolerant of ACE inhibitors (cough in 90%) with cardiovascular disease or diabetes with end-organ damage.
• How long: Median 56 months (IQR 51-64)
• Result: Primary composite 465 (15.7%) vs 504 (17.0%), hazard ratio 0.92, 95% CI 0.81-1.05, p=0.216. The secondary composite of cardiovascular death, MI or stroke was 384 (13.0%) vs 440 (14.8%), 0.87, 0.76-1.00, p=0.048 unadjusted but p=0.068 after adjustment for multiplicity.
• Funding: industry-funded; the paper's FUNDING statement reads "Boehringer Ingelheim."

465 (15.7%) patients experienced the primary outcome in the telmisartan group compared with 504 (17.0%) in the placebo group (hazard ratio 0.92, 95% CI 0.81-1.05, p=0.216). One of the secondary outcomes-a composite of cardiovascular death, myocardial infarction, or stroke-occurred in 384 (13.0%) patients on telmisartan compared with 440 (14.8%) on placebo (0.87, 0.76-1.00, p=0.048 unadjusted; p=0.068 after adjustment for multiplicity of comparisons and overlap with primary outcome)

Started soon after an ischaemic stroke, telmisartan did not significantly reduce recurrent stroke, major cardiovascular events or new diabetes. (Source 5)

• Randomized trial, High certainty.
• Size: 20,332 participants (10,146 telmisartan, 10,186 placebo)
• Who: People with a recent ischaemic stroke, randomised a median of 15 days after the stroke.
• How long: Mean follow-up 2.5 years.
• Result: Recurrent stroke 880 (8.7%) vs 934 (9.2%), hazard ratio 0.95, 95% CI 0.86 to 1.04, P=0.23; major cardiovascular events 13.5% vs 14.4%, HR 0.94, 0.87 to 1.01, P=0.11; new-onset diabetes 1.7% vs 2.1%, HR 0.82, 0.65 to 1.04, P=0.10. Blood pressure was 3.8/2.0 mmHg lower on telmisartan.
• Funding: not stated in the abstract.

A total of 880 patients (8.7%) in the telmisartan group and 934 patients (9.2%) in the placebo group had a subsequent stroke (hazard ratio in the telmisartan group, 0.95; 95% confidence interval [CI], 0.86 to 1.04; P=0.23). Major cardiovascular events occurred in 1367 patients (13.5%) in the telmisartan group and 1463 patients (14.4%) in the placebo group (hazard ratio, 0.94; 95% CI, 0.87 to 1.01; P=0.11). New-onset diabetes occurred in 1.7% of the telmisartan group and 2.1% of the placebo group (hazard ratio, 0.82; 95% CI, 0.65 to 1.04; P=0.10)

The FDA label states that no telmisartan trial has demonstrated a reduction in cardiovascular risk in people with hypertension. (Source 17)

• Official position, Moderate certainty.
• Size: not applicable.
• Who: People treated for hypertension.
• How long: not applicable.
• Result: No effect estimate is given; the label records the absence of such a trial.
• Funding: not applicable (regulatory position, label revised March 2025, SPL version 4 dated 28 September 2026)

There are no trials of telmisartan demonstrating reductions in cardiovascular risk in patients with hypertension, but at least one pharmacologically similar drug has demonstrated such benefits.

A much larger trial-level collaboration covering 138,769 participants, including 51,878 randomised to telmisartan, found no excess cancer with ARBs. (Source 18)

• Meta-analysis, Moderate certainty.
• Size: 138,769 participants in 15 trials; 134,914 analysed for incident cancer.
• Who: People at high cardiovascular risk randomised to telmisartan, irbesartan, valsartan, candesartan or losartan.
• How long: 23 to 60 months.
• Result: 4,549 (6.16%) of 73,808 on an ARB vs 3,856 (6.31%) of 61,106 controls; odds ratio 1.00, 95% CI 0.95-1.04. ARB alone versus ACE inhibitor alone 1.06 (0.97-1.16); ARB versus placebo/control without ACE inhibitor 0.97 (0.91-1.04). No excess of lung, prostate or breast cancer or of cancer deaths.
• Funding: not stated (collaboration of trial investigators)

Limit of this finding: The two totals in this paper do not add up: it describes 15 trials and 138,769 participants, while the arm totals it reports for cancer incidence are 73,808 on an ARB and 61,106 controls, which come to 134,914. The gap is in the source and comes from how the overlapping ARB-plus-ACE-inhibitor comparisons were counted; it does not change the result, which is no excess of cancer.

Overall, there was no excess of cancer incidence with ARB therapy compared to controls in the 15 trials [4549 (6.16%) cases of 73,808 allocated to ARB versus 3856 (6.31%) of 61 106 assigned to non-ARB controls; odds ratio (OR) 1.00, 95% confidence interval (CI) 0.95-1.04] overall or when individual ARBs were examined. ORs comparing combination therapy with ARB along with ACEi versus ACEi was 1.01 (95% CI 0.94-1.10), combination versus ARB alone 1.02 (95% CI 0.91-1.13), ARB alone versus ACEi alone 1.06 (95% CI 0.97-1.16) and ARB versus placebo/control without ACEi 0.97 (95% CI 0.91-1.04). There was no excess of lung, prostate or breast cancer, or overall cancer deaths associated with ARB treatment.

Pooled randomised evidence does not show that telmisartan improves fatty liver disease, and GGT rose slightly. (Source 6)

• Meta-analysis, Low certainty.
• Size: 258 participants across six randomised trials (126 telmisartan, 132 control)
• Who: Adults with metabolic dysfunction-associated steatotic liver disease.
• How long: not stated in the abstract.
• Result: Fasting blood sugar mean difference -2.78 mg/dL (95% CI -5.17 to -0.39; p = 0.023) with I2 = 91.8%; no significant change in BMI, waist circumference, HOMA-IR, lipids, ALT or AST; GGT +5.40 U/L (95% CI 0.51 to 10.29; p = 0.031); fibrosis stage -0.28 (95% CI -0.57 to 0.01; p = 0.060)
• Funding: not stated.

Limit of this finding: The authors' own conclusion is that the evidence does not show consistent benefit: the one significant result, a 2.78 mg/dL fall in fasting blood sugar, came with heterogeneity of 91.8% between the six trials, which means they disagreed with each other so much that the pooled figure should not be read as a reliable effect.

No significant changes were observed for body mass index, waist circumference, HOMA-IR, lipid profiles, ALT, or AST. Conversely, gamma-glutamyl transferase (GGT) levels showed a modest but significant increase with telmisartan (MD = 5.40 U/L; 95% CI 0.51 to 10.29; p = 0.031). Histological analyses revealed a non-significant trend toward fibrosis stage improvement (MD = -0.28; 95% CI -0.57 to 0.01; p = 0.060), with no significant improvements seen in the overall NAFLD activity score, steatosis, ballooning, or lobular inflammation.

Where the evidence is mixed

Telmisartan caused less cough and less angioedema than ramipril but more symptomatic low blood pressure. (Source 4)

• Randomized trial, High certainty.
• Size: 17,118 participants in the two monotherapy arms.
• Who: As above.
• How long: Median 56 months.
• Result: Cough 1.1% vs 4.2% (P<0.001); angioedema 0.1% vs 0.3% (P=0.01); hypotensive symptoms 2.6% vs 1.7% (P<0.001); syncope 0.2% in both.
• Funding: not stated in the abstract.

As compared with the ramipril group, the telmisartan group had lower rates of cough (1.1% vs. 4.2%, P<0.001) and angioedema (0.1% vs. 0.3%, P=0.01) and a higher rate of hypotensive symptoms (2.6% vs. 1.7%, P<0.001); the rate of syncope was the same in the two groups (0.2%)

A single small one-year trial in non-alcoholic steatohepatitis reported histological improvement with telmisartan plus lifestyle change, but only 30 of 50 randomised participants were analysed. (Source 19)

• Randomized trial, Very low certainty.
• Size: 50 randomised (35 telmisartan plus lifestyle, 15 lifestyle only); 30 analysed (20 vs 10)
• Who: Adults with biopsy-proven non-alcoholic steatohepatitis.
• How long: 1 year.
• Result: NAFLD activity score improvement 2.15 +/- 1.66 vs 1.10 +/- 0.57 (P = 0.017); fibrosis improvement 0.65 +/- 0.93 vs -0.30 +/- 0.48 (P = 0.001); regression odds ratio 92.07 with a confidence interval of 1.39 to 6106.
• Funding: not stated.

Limit of this finding: Read the percentages against the right denominator: 50 people were randomised but only 30 were analysed - 20 of 35 on telmisartan and 10 of 15 on lifestyle change alone - so "65% improved" means 13 of the 20 who were still being measured, not 13 of 35. The regression result is printed as an odds ratio of 92.07 with a confidence interval from 1.39 to 6106, a range so wide that it tells you almost nothing about the size of any effect.

At the end of study, NAS improvement in TL and L groups was 2.15 ± 1.66 and 1.10 ± 0.57 (P = 0.017) and fibrosis improvement was 0.65 ± 0.93 and -0.30 ± 0.48 (P = 0.001), respectively. NAS improved by ≥ 2 in 13 (65%) and 2 (20%) patients and fibrosis score improved by ≥ 1 in 8 (40%) patients and none of the patients in TL group and L group, respectively. Telmisartan and life style modification could improve steatosis, ballooning, lobular inflammation, and fibrosis. Life style modification could improve ballooning only, but fibrosis deteriorated. TL group showed improvement in NAS and fibrosis score [P value: 0.035; odds ratio (OR) =92.07, confidence interval (CI) =1.39-6106] to the level of response by regression analysis.

Where the research disagrees

Whether angiotensin receptor blockers, and telmisartan in particular, increase the risk of new cancer

• Sipahi and colleagues, Lancet Oncology 2010, meta-analysis of five to eight randomised trials, 61,590 to 93,515 participants, telmisartan 85.7% of ARB exposure: Patients randomly assigned to receive ARBs had a significantly increased risk of new cancer occurrence compared with patients in control groups (7.2%vs 6.0%, risk ratio [RR] 1.08, 95% CI 1.01-1.15; p=0.016). (Source 15)
• ARB Trialists Collaboration, Journal of Hypertension 2011, trial-level collaboration of 15 randomised trials, 138,769 participants, including 51,878 on telmisartan: Overall, there was no excess of cancer incidence with ARB therapy compared to controls in the 15 trials (Source 18)

Whether telmisartan reduces cardiovascular events compared with placebo in people who cannot take an ACE inhibitor

• TRANSCEND investigators, Lancet 2008, randomised placebo-controlled trial, 5,926 participants; the trial was funded by Boehringer Ingelheim, which the abstract states in a separate FUNDING section, not as part of this interpretation: Although the drug had no significant effect on the primary outcome of this study, which included hospitalisations for heart failure, it modestly reduced the risk of the composite outcome of cardiovascular death, myocardial infarction, or stroke. (Source 20)
• FDA-approved telmisartan labelling, regulatory position based on ONTARGET and TRANSCEND, label revised March 2025: Studies of telmisartan in this setting do not exclude the possibility that telmisartan may not preserve a meaningful fraction of the effect of the ACE inhibitor to which it was compared. (Source 21)

How much

• Reference intake: Telmisartan is a prescription medicine; the dose is set by the prescriber. The FDA label (SPL version 4, dated 28 September 2026; label revised March 2025) states that dosage must be individualised and that the usual starting dose is 40 mg once a day, with blood pressure response dose-related over 20 to 80 mg. (Source 22)
• Upper limit: There is no reference intake or tolerable upper intake level for a prescription drug. The label records a maximum recommended human dose of 80 mg per day, and states that doses up to 160 mg produced no further blood pressure fall. (Source 23)
• Studied: ONTARGET gave telmisartan 80 mg per day for a median of 56 months, compared with ramipril 10 mg per day or both. (Source 4)
• Studied: TRANSCEND gave telmisartan 80 mg per day versus placebo for a median of 56 months. (Source 13)
• Studied: The stroke-prevention trial gave telmisartan 80 mg daily versus placebo for a mean of 2.5 years. (Source 5)
• Studied: The six principal hypertension trials studied a range of 20 to 160 mg once daily. (Source 3)
• Studied: The non-alcoholic steatohepatitis trial gave telmisartan 40 or 80 mg once daily with lifestyle modification for 1 year; 50 people were randomised and 30 were analysed. (Source 24)

A common belief, and what the research shows

The belief: If one drug that blocks the renin-angiotensin system helps, blocking it twice - an ARB plus an ACE inhibitor - must help more.

What the research shows: ONTARGET tested exactly that in 25,620 people and found no extra benefit and more harm: "Patients receiving the combination of telmisartan and ramipril did not obtain any additional benefit compared to monotherapy, but experienced an increased incidence of renal dysfunction (e.g., acute renal failure) compared with groups receiving telmisartan alone or ramipril alone." The trial report records "an increased risk of hypotensive symptoms (4.8% vs. 1.7%, P<0.001), syncope (0.3% vs. 0.2%, P=0.03), and renal dysfunction (13.5% vs. 10.2%, P<0.001)".

Questions and answers

What is it?

Telmisartan is a prescription tablet in the angiotensin receptor blocker class, used mainly for high blood pressure. It works at the AT1 receptor, where the hormone angiotensin II would normally dock. Unlike ACE inhibitors it does not block the enzyme that makes angiotensin II, so it does not interfere with bradykinin. (Source 1)

What does it do in the body?

Angiotensin II tightens blood vessels, prompts aldosterone release, stimulates the heart and makes the kidney reabsorb sodium. Telmisartan occupies the receptor so angiotensin II cannot do those things, and blood pressure falls. It has more than 3,000-fold greater affinity for the AT1 receptor than for the AT2 receptor. (Source 1)

Is it good or bad for you?

It depends heavily on the situation. In people at high cardiovascular risk who cannot take an ACE inhibitor, the placebo-controlled trial missed its primary endpoint. In people already on ramipril, adding telmisartan made things worse. And in pregnancy it is harmful enough to carry a boxed warning. Its clearest benefit is lowering blood pressure, and compared with ramipril it caused much less cough. (Source 4)

How do you get more of it?

Telmisartan is not a nutrient and there is no food or supplement source. It is available only on prescription and the dose is chosen by the prescriber, starting usually at 40 mg once a day and adjusted according to blood pressure. The label states that dosage must be individualised. (Source 22)

If it is harmful, what reduces it?

If telmisartan needs to be cleared from the body, stopping it is the route: it has a half-life of about 24 hours and is removed in the bile, not the urine. Dialysis does not remove it. Blood pressure returns to its untreated level over several days to a week. (Source 9)

Why might someone be low in it or missing it?

Someone may not be on telmisartan because it is contraindicated - a previous anaphylactic or angioedema reaction to it, or diabetes while taking aliskiren. It is also stopped in pregnancy, and avoided in combination with an ACE inhibitor. People with biliary obstruction or liver impairment clear it more slowly, so it is started low and titrated slowly. (Source 12)

Which whole foods contain it or feed it?

No food contains telmisartan. Two food-related points matter: food slightly lowers how much is absorbed, by about 6% at 40 mg and 20% at 160 mg, which is why it can be taken with or without food; and potassium-containing salt substitutes should not be used without asking the prescriber, because telmisartan already tends to raise potassium. (Source 7)

What happens if you do not have it?

Telmisartan is a medicine, so 'absence' means untreated or differently treated blood pressure rather than a deficiency. Raised systolic or diastolic pressure itself increases cardiovascular risk, and the absolute risk added per mmHg is greater at higher pressures, so the benefit from lowering it is largest in people whose risk is highest to begin with. (Source 25)

How can you test for it?

There is no routine blood test for telmisartan itself in ordinary care. What is monitored is the effect and the side effects: blood pressure, including 24-hour ambulatory monitoring in the trials, plus blood electrolytes for potassium and creatinine for kidney function in people at risk. Telmisartan trough levels run at only 10% to 25% of peak, so a single blood level would be hard to interpret. (Source 8)

References

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2. DailyMed / U.S. National Library of Medicine (labeler: Preferred Pharmaceuticals Inc.; manufactured by Inventia Healthcare, distributed by Ascend Laboratories). TELMISARTAN tablet, USP - prescribing information (FDA label, Highlights and full label), SPL version 4. 2026. Read the source
3. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 14.1 Hypertension (clinical studies). 2026. Read the source
4. New England Journal of Medicine. Telmisartan, ramipril, or both in patients at high risk for vascular events.. 2008. PMID 18378520, DOI 10.1056/NEJMoa0801317. Read the source
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7. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 17 Patient Counseling Information. 2026. Read the source
8. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 5.3 Hyperkalemia. 2026. Read the source
9. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 12.3 Pharmacokinetics. 2026. Read the source
10. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 12.3 Pharmacokinetics - Metabolism and Elimination. 2026. Read the source
11. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 7 Drug Interactions. 2026. Read the source
12. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 5.6 Dual Blockade of the Renin-Angiotensin-Aldosterone System (RAS). 2026. Read the source
13. Lancet. Effects of the angiotensin-receptor blocker telmisartan on cardiovascular events in high-risk patients intolerant to angiotensin-converting enzyme inhibitors: a randomised controlled trial.. 2008. PMID 18757085, DOI 10.1016/S0140-6736(08)61242-8. Read the source
14. DailyMed / U.S. National Library of Medicine. Telmisartan tablets - prescribing information, Section 5.1 Fetal Toxicity. 2026. Read the source
15. Lancet Oncology. Angiotensin-receptor blockade and risk of cancer: meta-analysis of randomised controlled trials.. 2010. PMID 20542468, DOI 10.1016/S1470-2045(10)70106-6. Read the source
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18. Journal of Hypertension. Effects of telmisartan, irbesartan, valsartan, candesartan, and losartan on cancers in 15 trials enrolling 138,769 individuals.. 2011. PMID 21358417, DOI 10.1097/HJH.0b013e328344a7de. Read the source
19. Saudi Journal of Gastroenterology. Effect of telmisartan on histological activity and fibrosis of non-alcoholic steatohepatitis: A 1-year randomized control trial.. 2016. PMID 26831610, DOI 10.4103/1319-3767.173762. Read the source
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23. DailyMed / U.S. National Library of Medicine. TELMISARTAN tablet, USP - prescribing information, Section 8.1 Pregnancy (Fetal/Neonatal adverse reactions and Animal Data). 2026. Read the source
24. Saudi Journal of Gastroenterology. Effect of telmisartan on histological activity and fibrosis of non-alcoholic steatohepatitis: A 1-year randomized control trial (Patients and Methods).. 2016. PMID 26831610, DOI 10.4103/1319-3767.173762. Read the source
25. DailyMed / U.S. National Library of Medicine. Telmisartan tablets - prescribing information (FDA label), Section 1.1 Hypertension. 2026. Read the source