Hydralazine

What it is

Hydralazine is a small synthetic molecule (1-hydrazinophthalazine monohydrochloride) given as a tablet or by injection to lower blood pressure. It acts directly on the muscle of small arteries rather than through the nervous system or the kidney. It is metabolised in the liver by acetylation, and people differ genetically in how fast they do this, which changes blood levels substantially. It has been in clinical use since the 1950s.

What the research says

The outcome evidence is split by what it is used for. For lowering blood pressure in essential hypertension the drug is approved but modern outcome-trial evidence in that setting is thin, and the label's own adverse-event list carries no frequency data. The strongest randomised outcome evidence for hydralazine is as a fixed-dose combination with isosorbide dinitrate in self-identified Black patients with advanced heart failure (A-HeFT), where all-cause death fell from 10.2% to 6.2%. Against that, when the same hydralazine-nitrate combination was compared head to head with enalapril in heart failure (V-HeFT II), enalapril produced lower mortality. In severe hypertension in pregnancy a meta-analysis found hydralazine performed worse than nifedipine and caused more maternal and fetal adverse effects than comparators. Drug-induced lupus and ANCA-associated vasculitis are its signature serious harms.

Evidence grade: Disputed.

How it works

Drug class: Direct-acting arteriolar vasodilator (antihypertensive)

Hydralazine relaxes the muscle in the walls of small arteries, which widens them and lowers blood pressure. The label states the precise mechanism is still not fully understood, but describes interference with calcium movement inside vascular smooth muscle. Because blood pressure falls, the body responds reflexively with a faster heart rate and more renin release, which is why hydralazine is usually combined with a beta blocker and a diuretic. (Source 1)

What it is used for

• The US label approves hydralazine for essential hypertension, alone or as an adjunct, and gives a titration schedule. The label itself records that frequency data for its adverse reactions were never systematically collected, and we found no modern placebo-controlled cardiovascular outcome trial of hydralazine monotherapy in hypertension; this is a regulatory position dating from an era before outcome trials were required. Evidence: limited. (Source 2)
• In the A-HeFT randomised trial of 1,050 Black patients with NYHA class III-IV heart failure, adding fixed-dose isosorbide dinitrate plus hydralazine to standard therapy cut all-cause death from 10.2% to 6.2% and reduced first hospitalisation for heart failure. The abstract record puts that hospitalisation comparison at 16.4% against 22.4% while calling it a 33 percent relative reduction; the two do not agree, so the exact placebo rate should not be quoted (see the caveat on the A-HeFT finding). The trial was stopped early for benefit. The label for the combination product restricts the indication to self-identified Black patients. Evidence: established. (Source 3)
• V-HeFT II randomised 804 men with heart failure to enalapril or hydralazine plus isosorbide dinitrate. Two-year mortality was 18% on enalapril versus 25% on hydralazine-isosorbide dinitrate. Hydralazine-nitrate therapy is therefore not a substitute for an ACE inhibitor. Evidence: not-supported. (Source 4)
• A 2003 meta-analysis of 21 randomised trials in 893 women found hydralazine caused more maternal hypotension, more caesarean sections, more placental abruption, more maternal oliguria and more adverse fetal heart rate effects than comparator drugs, and more severe hypertension than nifedipine or isradipine. The authors concluded the data do not support hydralazine as first-line treatment. The US labels for oral and injectable hydralazine we read do not list pregnancy hypertension as an indication. Evidence: not-supported. (Source 5)

Interactions

• Food (any meal) (pharmacokinetic study): Eating when you take a conventional hydralazine tablet raises the amount of drug that reaches the bloodstream by two to three times, which can mean a larger drop in blood pressure. The label records the same direction of effect. (Source 6)
• Food (any meal) - label position (label): The manufacturer's label records the food effect in a single sentence without quantifying it. (Source 7)
• Pyridoxine (vitamin B6) (label): Hydralazine can cause pins and needles, numbness and tingling in the hands and feet. The label attributes this to an anti-vitamin-B6 effect and says pyridoxine should be added if those symptoms appear. This is an interaction in which the drug depletes a vitamin, rather than the vitamin changing the drug. (Source 8)
• Potassium chloride (potassium supplements) (pharmacokinetic study): A crossover study in 12 healthy men found a potassium chloride solution did not change how much hydralazine was absorbed from a sustained-release product. This is a documented absence of interaction, not a documented interaction. (Source 9)
• Monoamine oxidase (MAO) inhibitors (label): The label advises caution when MAO inhibitors are used in someone taking hydralazine, without quantifying the risk. (Source 10)
• Diazoxide injection and other potent parenteral antihypertensives (label): Combining hydralazine with powerful injected blood-pressure drugs can cause a severe fall in blood pressure. (Source 10)
• PDE5 inhibitors (sildenafil, tadalafil, vardenafil, avanafil) and riociguat - for the isosorbide dinitrate/hydralazine combination product only (label): The combination tablet contains a nitrate, and nitrates plus erectile-dysfunction drugs of this class can cause severe hypotension, fainting or heart muscle ischaemia. The combination product is contraindicated with them. This applies to the nitrate component, not to hydralazine alone. (Source 11)

Stopping it

• There is no withdrawal syndrome or dependence described for hydralazine. The documented risk of stopping suddenly is loss of blood-pressure or afterload control: a 1979 case report describes severe congestive heart failure precipitated by abrupt withdrawal in a patient taking hydralazine for afterload reduction, which reversed when the drug was restarted. This is a single case report and the weakest kind of evidence. (Source 12)
• When hydralazine causes a lupus-like syndrome, the label's position is that the drug should be stopped unless the benefit-risk balance requires continuing it, and that signs usually regress after stopping although lasting effects have been found years later. (Source 13)
• If blood counts fall (anaemia, low white cells, agranulocytosis, purpura), the label's position is that treatment should be stopped. (Source 14)

What goes wrong

In severe hypertension in pregnancy, hydralazine produced more maternal hypotension, more caesarean sections, more placental abruption and more adverse fetal heart-rate effects than comparator antihypertensives. (Source 5)

• Meta-analysis, Low certainty.
• Size: 21 randomised trials, 893 women.
• Who: pregnant women with severe hypertension.
• How long: short-acting treatment episodes.
• Result: Maternal hypotension RR 3.29 (95% CI 1.50 to 7.23, 13 trials); caesarean section RR 1.30 (1.08 to 1.59, 14 trials); placental abruption RR 4.17 (1.19 to 14.28, 5 trials); maternal oliguria RR 4.00 (1.22 to 12.50, 3 trials); adverse fetal heart rate effects RR 2.04 (1.32 to 3.16, 12 trials); low 1-minute Apgar RR 2.70 (1.27 to 5.88, 3 trials); maternal side effects RR 1.50 (1.16 to 1.94, 12 trials)
• Funding: not stated; the review notes significant heterogeneity and differences in methodological quality between trials.

Hydralazine was associated with more maternal hypotension (3.29 (1.50 to 7.23); 13 trials); more caesarean sections (1.30 (1.08 to 1.59); 14 trials); more placental abruption (4.17 (1.19 to 14.28); five trials)

In a population cohort of older adults, new hydralazine use was associated with a 0.3 percentage point higher absolute risk of vasculitis than an ACE inhibitor or ARB, and the association disappeared once competing risk of death was accounted for. (Source 15)

• Cohort study, Low certainty.
• Size: 583,136 adults (40,748 on hydralazine, 542,388 on an ACE inhibitor or ARB)
• Who: adults aged 66 years or older newly prescribed the drug in Ontario, Canada, 2008-2021.
• How long: 2008 to 2021.
• Result: Vasculitis in 328 (0.8%) of hydralazine users vs 2,712 (0.5%) of ACE/ARB users; absolute risk difference 0.3 percentage points; hazard ratio 1.19 (95% CI 1.04-1.37); not significant after accounting for competing risk of death.
• Funding: not stated in the abstract we read.

Limit of this finding: The published abstract contains an impossible figure. It describes 583 136 adults of whom '51 827 [55.2%] female', but 51 827 is about 9 percent of 583 136, not 55.2 percent. We fetched the record twice to be sure: the error is the journal's, and it cannot be resolved from the abstract. Take neither the count nor the percentage as the sex breakdown of this cohort. The event counts, the hazard ratio and the competing-risk result are internally consistent and are not affected by it. Two further limits on reading this: the cohort was adults aged 66 years or older in Ontario, Canada, so it is not a general-population estimate, and the authors' own conclusion is that vasculitis was rare and that hydralazine is unlikely to be associated with a clinically meaningful increased risk of it.

absolute risk difference, 0.3 percentage points; hazard ratio, 1.19; 95% CI, 1.04-1.37). Results were no longer significant when accounting for the competing risk of death.

Hydralazine can produce a drug-induced lupus syndrome, including glomerulonephritis, that usually but not always regresses when the drug is stopped. (Source 13)

• Official position, Certainty not rated.
• Size: not stated.
• Who: patients taking hydralazine.
• How long: weeks to years of exposure.
• Result: No frequency given on the label; the label states signs usually regress on discontinuation but residua have been detected many years later, and that long-term steroids may be needed.
• Funding: not applicable (regulatory label, this version published Sep 21, 2026)

In a few patients hydrALAZINE may produce a clinical picture simulating systemic lupus erythematosus including glomerulonephritis.

A case report states hydralazine-induced lupus occurs in 5-10% of people taking the drug; this figure comes from a case report's introduction rather than from a cohort study, so it should be treated as an unverified secondary claim. (Source 16)

• Case report, Very low certainty.
• Size: one 76-year-old woman.
• Who: older woman with CKD, hyperlipidaemia, hypertension and type 2 diabetes on hydralazine.
• How long: not stated.
• Result: ANA titre 1:1280, positive anti-histone antibodies, pancytopenia; improvement after hydralazine was stopped.
• Funding: not stated.

Hydralazine-induced lupus syndrome was first reported in 1953, and only occurs in 5-10% of patients taking hydralazine.

The fixed-dose hydralazine-isosorbide dinitrate combination caused headache in half of patients and dizziness in a third, and twice as many patients stopped it for side effects as stopped placebo. (Source 17)

• Randomized trial, Moderate certainty.
• Size: 517 on drug, 527 on placebo (A-HeFT safety population)
• Who: Black adults with advanced heart failure.
• How long: up to 12 months or more.
• Result: Headache 50% vs 21%; dizziness 32% vs 14%; asthenia 14% vs 11%; nausea 10% vs 6%; hypotension 8% vs 4%; discontinuation for adverse reactions 21% vs 12%; headache was the commonest reason for stopping (7%)
• Funding: industry (reported in the manufacturer's label, published Jan 22, 2026)

Limit of this finding: The percentages come from a table on the label. In our record that table is held as a list of names and numbers, and the two numbers after each reaction name are, in order, the percentage on BiDil (517 patients) and the percentage on placebo (527 patients); the column labels sit at the top of the recorded table, not beside each row. These are also rates in A-HeFT, where everyone was also on standard heart-failure therapy and on a fixed combination of hydralazine with isosorbide dinitrate, so they are not the rates for hydralazine taken on its own.

In A-HeFT, 21% of the patients discontinued BiDil for adverse reactions compared to 12% who discontinued placebo.

The hydralazine label's own adverse-reaction list has no frequency estimates because the data were never systematically collected. (Source 18)

• Official position, Certainty not rated.
• Size: not stated.
• Who: patients taking hydralazine.
• How long: not stated.
• Result: Listed as 'Common': headache, anorexia, nausea, vomiting, diarrhoea, palpitations, tachycardia, angina pectoris. Less frequent: hypotension, peripheral neuritis, blood dyscrasias including agranulocytosis, paralytic ileus.
• Funding: not applicable (regulatory label)

The following adverse reactions have been observed, but there has not been enough systematic collection of data to support an estimate of their frequency.

Hydralazine increased lung tumours in mice and benign liver nodules in rats at doses many times the human dose, and was mutagenic in bacterial systems; the label states the human relevance is uncertain. (Source 19)

• Animal study, Low certainty.
• Size: lifetime mouse study and 2-year rat study.
• Who: Swiss albino mice and rats.
• How long: lifetime / 2 years.
• Result: Mice given about 250 mg/kg per day (about 80 times the maximum recommended human dose) had significantly more lung adenomas and adenocarcinomas; rats at 15, 30 and 60 mg/kg/day had more benign neoplastic liver nodules and testicular interstitial cell tumours.
• Funding: not applicable (regulatory label)

While long-term clinical observation has not suggested that human cancer is associated with hydrALAZINE use, epidemiologic studies have so far been insufficient to arrive at any conclusions.

What the evidence supports

Adding fixed-dose isosorbide dinitrate plus hydralazine to standard heart-failure therapy reduced all-cause death from 10.2% to 6.2% in Black patients with advanced heart failure (absolute risk reduction 4.0 percentage points, about 25 people treated for one death avoided). (Source 3)

• Randomized trial, Moderate certainty.
• Size: 1,050 patients.
• Who: Black adults with NYHA class III or IV heart failure and dilated ventricles, on standard therapy including neurohormonal blockers.
• How long: stopped early; mean follow-up about 10 months.
• Result: Death from any cause 6.2% vs 10.2% (P=0.02); hazard ratio 0.57. First heart-failure hospitalisation is given in the abstract record as 16.4% vs 22.4% (P=0.001) and described in the same sentence as a 33 percent relative reduction; those two statements are inconsistent, so the placebo figure should not be treated as established (see caveat). Quality-of-life score change -5.6 vs -2.7 (P=0.02)
• Funding: industry-funded (NitroMed)

Limit of this finding: The abstract record we quote gives the first-hospitalisation rates as 16.4 percent versus 22.4 percent, but the same sentence calls that a 33 percent relative reduction, and 16.4 against 22.4 is a reduction of about 27 percent, not 33 percent. The two numbers in one sentence cannot both be right. We re-fetched the NLM record twice: 22.4 is what the record itself prints, so this is the source's error, not a transcription slip. Independent summaries of this trial give the placebo rate as 24.4 percent, which does match the stated 33 percent reduction. Read the hospitalisation comparison as approximate: fewer hospitalisations on the combination is not in doubt, but the exact placebo figure in this record is unreliable and should not be quoted as fact. The mortality figures in the same passage (10.2 percent versus 6.2 percent, hazard ratio 0.57) are internally consistent and unaffected.

The study was terminated early owing to a significantly higher mortality rate in the placebo group than in the group given isosorbide dinitrate plus hydralazine (10.2 percent vs. 6.2 percent, P=0.02)

What the evidence does not support

Hydralazine plus isosorbide dinitrate was inferior to enalapril for survival in chronic heart failure. (Source 4)

• Randomized trial, Moderate certainty.
• Size: 804 men.
• Who: men with chronic congestive heart failure on digoxin and a diuretic.
• How long: 2 years and beyond.
• Result: Two-year mortality 25% on hydralazine-isosorbide dinitrate vs 18% on enalapril (P=0.016); peak exercise oxygen consumption increased only with hydralazine-isosorbide dinitrate (P less than 0.05)
• Funding: not stated (US Veterans Administration cooperative study)

Mortality after two years was significantly lower in the enalapril arm (18 percent) than in the hydralazine-isosorbide dinitrate arm (25 percent) (P = 0.016; reduction in mortality, 28.0 percent)

Hydralazine was no better than nifedipine or isradipine for persistent severe hypertension in pregnancy, and the review's authors judged the data too weak to guide practice. (Source 5)

• Meta-analysis, Very low certainty.
• Size: four trials for this comparison, within 21 trials of 893 women.
• Who: pregnant women with severe hypertension.
• How long: short-acting treatment episodes.
• Result: More persistent severe hypertension than nifedipine or isradipine, RR 1.41 (95% CI 0.95 to 2.09); versus labetalol RR 0.29 (0.08 to 1.04), neither statistically significant.
• Funding: not stated.

but more severe hypertension than nifedipine or isradipine (1.41 (0.95 to 2.09); four trials); there was significant heterogeneity in outcome between trials and differences in methodological quality

Taking a potassium chloride solution alongside a sustained-release hydralazine product did not change hydralazine absorption. (Source 9)

• Blood level study, Low certainty.
• Size: 12 healthy male volunteers.
• Who: healthy men.
• How long: single dose, 14 hours of blood sampling, two-way crossover.
• Result: No difference in AUC, Cmax or Tmax with versus without concomitant KCl solution.
• Funding: not stated.

showed that KCl had no influence on the bioavailability or release characteristics of hydralazine from the sustained-release formulation

Where the research disagrees

Whether hydralazine meaningfully causes ANCA-associated vasculitis

• Case-report and case-series literature, case report; the 5-10% figure is asserted in the report's introduction, not measured in it: Hydralazine-induced lupus syndrome was first reported in 1953, and only occurs in 5-10% of patients taking hydralazine. (Source 16)
• Fremont and colleagues, JAMA Network Open 2026 population cohort, retrospective population cohort of 583,136 older adults with an active comparator: hazard ratio, 1.19; 95% CI, 1.04-1.37). Results were no longer significant when accounting for the competing risk of death. (Source 15)

Whether hydralazine should be used for severe hypertension in pregnancy

• Magee and colleagues, BMJ 2003 meta-analysis, meta-analysis of 21 randomised trials, 893 women, with acknowledged heterogeneity and quality limits: Hydralazine was associated with more maternal hypotension (3.29 (1.50 to 7.23); 13 trials); more caesarean sections (1.30 (1.08 to 1.59); 14 trials) (Source 5)
• US prescribing information for hydralazine tablets (published Sep 21, 2026), regulatory position; pregnancy hypertension is not an approved indication on this label: Essential hypertension, alone or as an adjunct. (Source 2)

How much

• Reference intake: Dosing is set by the prescriber. As a position, the US label (SPL version published Sep 21, 2026) describes starting at 10 mg four times daily for 2 to 4 days, then 25 mg four times daily for the rest of the first week, then 50 mg four times daily from the second week, adjusted down to the lowest effective level. (Source 20)
• Upper limit: As a position, the same label states that up to 300 mg daily may be required in a few resistant patients, and warns in the same section that toxic reactions, particularly the lupus-like syndrome, are more common at large doses. (Source 20)
• Studied: V-HeFT II gave 300 mg of hydralazine plus 160 mg of isosorbide dinitrate daily, compared against 20 mg of enalapril daily, in 804 men with heart failure. (Source 4)
• Studied: A-HeFT used a fixed-dose isosorbide dinitrate plus hydralazine tablet added to standard therapy in 1,050 Black patients with class III-IV heart failure. (Source 3)

A common belief, and what the research shows

The belief: Hydralazine is a proven first-line heart failure drug for everyone.

What the research shows: The randomised evidence for benefit is specific. A-HeFT tested the fixed-dose hydralazine-nitrate combination added to standard therapy in Black patients with class III-IV heart failure, and the approved indication for that product is written for that group: "BiDil is indicated for the treatment of heart failure as an adjunct to standard therapy in self-identified black patients to improve survival". When hydralazine plus isosorbide dinitrate was compared directly with an ACE inhibitor in a broader heart failure population, it lost: "Mortality after two years was significantly lower in the enalapril arm (18 percent) than in the hydralazine-isosorbide dinitrate arm (25 percent) (P = 0.016; reduction in mortality, 28.0 percent)".

Questions and answers

What is it?

Hydralazine is a prescription-only synthetic drug that widens small arteries to lower blood pressure. It is taken as a tablet several times a day, or given by injection in hospital when blood pressure must come down quickly. It has been used since the 1950s and is approved in the US for essential hypertension, alone or alongside other drugs. (Source 2)

What does it do in the body?

It relaxes the muscle in the walls of arterioles, so those vessels widen, resistance falls and blood pressure drops. The label states the exact mechanism is not fully understood but describes interference with calcium movement in vascular smooth muscle. Because arteries are dilated more than veins, standing dizziness is less of a problem than with some older drugs, but the heart speeds up and renin rises in response. (Source 1)

Is it good or bad for you?

It depends entirely on the setting. In Black patients with advanced heart failure, the fixed-dose combination with isosorbide dinitrate reduced death from 10.2% to 6.2% in a randomised trial. As a substitute for an ACE inhibitor in heart failure it was worse than enalapril. In severe hypertension in pregnancy a meta-analysis found more harms than with comparator drugs. It also carries a specific risk of a lupus-like autoimmune syndrome, which is more likely at higher doses. (Source 20)

How do you get more of it?

Hydralazine is a prescription medicine, not a nutrient; the only way to take it is for a prescriber to prescribe it, and the dose is set by the prescriber. One thing that changes how much gets into the blood is food: a pharmacokinetic study in 5 healthy men found taking a conventional tablet with a meal raised bioavailability two- to three-fold, and the label records the same effect. (Source 7)

If it is harmful, what reduces it?

If hydralazine is causing harm, the documented response in the literature and on the label is to stop the drug, under medical supervision. The lupus-like syndrome usually regresses after stopping, though lasting effects have been reported years later, and long-term steroid treatment is sometimes needed. Case reports of hydralazine-associated ANCA vasculitis describe stopping the drug alongside immunosuppressive treatment. One 1979 single-patient report describes severe heart failure after sudden withdrawal in someone taking it for afterload reduction, so abrupt stopping is not without risk either. (Source 13)

Why might someone be low in it or missing it?

This question is about nutrients rather than drugs, so it does not apply directly. The nearest equivalent is why blood levels differ so much between people on the same dose: hydralazine is broken down by acetylation, and slow acetylators reach higher levels and need lower doses. Levels are also lower when it is taken on an empty stomach than with food. (Source 21)

Which whole foods contain it or feed it?

No whole food contains hydralazine; it is a synthetic drug. Food matters only in that eating raises the amount absorbed from a conventional tablet two- to three-fold in pharmacokinetic studies, so whether doses are taken consistently with or without food changes blood levels. (Source 6)

What happens if you do not have it?

Not taking hydralazine is normal for almost everyone; it is one of several options for lowering blood pressure, not something the body needs. For the one group with randomised outcome evidence - Black patients with advanced heart failure already on standard therapy - not having the fixed-dose hydralazine-nitrate combination meant a higher death rate in A-HeFT (10.2% on placebo versus 6.2%) and more first hospitalisations for heart failure. The abstract record puts that hospitalisation difference at 16.4% versus 22.4% while calling it a 33 percent relative reduction, and those two statements do not agree, so the exact placebo figure is unreliable. Sudden withdrawal in someone being treated for heart failure has been reported, in a 1979 single-patient report, to precipitate severe congestive heart failure. (Source 3)

How can you test for it?

There is no routine blood level test for hydralazine in ordinary care. What the label does specify is safety monitoring: full blood counts and antinuclear antibody (ANA) titres before and periodically during prolonged treatment, even in someone with no symptoms, and again if joint pain, fever, chest pain or ongoing malaise appear. A positive ANA is not by itself proof of drug-induced lupus; the label says a positive titre requires weighing the test result against the benefit of continuing treatment. (Source 14)

References

1. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7. 2026. Read the source
2. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7 - Section INDICATIONS AND USAGE. 2026. Read the source
3. The New England journal of medicine. Combination of isosorbide dinitrate and hydralazine in blacks with heart failure.. 2004. PMID 15533851, DOI 10.1056/nejmoa042934. Read the source
4. The New England journal of medicine. A comparison of enalapril with hydralazine-isosorbide dinitrate in the treatment of chronic congestive heart failure.. 1991. PMID 2057035, DOI 10.1056/nejm199108013250502. Read the source
5. BMJ (Clinical research ed.). Hydralazine for treatment of severe hypertension in pregnancy: meta-analysis.. 2003. PMID 14576246, DOI 10.1136/bmj.327.7421.955. Read the source
6. Clinical pharmacology and therapeutics. Enhancement of hydralazine bioavailability by food.. 1977. PMID 872490, DOI 10.1002/cpt1977221104. Read the source
7. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7 - Section PRECAUTIONS / Drug/Food Interactions. 2026. Read the source
8. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7 - Section PRECAUTIONS / General. 2026. Read the source
9. Journal of pharmaceutical sciences. Comparative bioavailability of a sustained-release ion-exchange hydralazine product with a potassium (cation) challenge.. 1992. PMID 1522491, DOI 10.1002/jps.2600810614. Read the source
10. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7 - Section PRECAUTIONS / Drug/Drug Interactions. 2026. Read the source
11. DailyMed, U.S. National Library of Medicine (label version published Jan 22, 2026). BIDIL (hydralazine hydrochloride and isosorbide dinitrate) tablet, film coated [Azurity Pharmaceuticals, Inc.] - FDA prescribing information, SPL version 13 - Section 4 CONTRAINDICATIONS. 2026. Read the source
12. Chest. Precipitation of heart failure following sudden withdrawal of hydralazine.. 1979. PMID 436528, DOI 10.1378/chest.75.6.724. Read the source
13. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7 - Section WARNINGS. 2026. Read the source
14. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7 - Section PRECAUTIONS / Laboratory Tests. 2026. Read the source
15. JAMA network open. Hydralazine Use and Risk of Vasculitis.. 2026. PMID 41838000, DOI 10.1001/jamanetworkopen.2026.1943. Read the source
16. Cureus. Drug-Induced Systemic Lupus Erythematosus: A Rare Presentation of Hydralazine-Induced Lupus.. 2024. PMID 39575041, DOI 10.7759/cureus.72069. Read the source
17. DailyMed, U.S. National Library of Medicine (label version published Jan 22, 2026). BIDIL (hydralazine hydrochloride and isosorbide dinitrate) tablet, film coated [Azurity Pharmaceuticals, Inc.] - FDA prescribing information, SPL version 13 - Section 6.1 Clinical Trials Experience (A-HeFT narrative). 2026. Read the source
18. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7. 2026. Read the source
19. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7 - Section PRECAUTIONS / Carcinogenesis, Mutagenesis, Impairment of Fertility, part 2 of 2. 2026. Read the source
20. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7. 2026. Read the source
21. DailyMed, U.S. National Library of Medicine (label version published Sep 21, 2026). HYDRALAZINE HYDROCHLORIDE tablet [Bryant Ranch Prepack] - FDA prescribing information, SPL version 7. 2026. Read the source