Olopatadine

What it is

Olopatadine is a second-generation antihistamine: a histamine H1 receptor antagonist that also damps down the release of inflammatory mediators from human mast cells. In the United States it is sold as eye drops, now over the counter, for itchy allergic eyes, as a prescription nasal spray for seasonal hay fever, and as a fixed-dose nasal combination with the steroid mometasone furoate. An oral tablet form is marketed in some Asian countries but not in the US. Even the nasal spray is absorbed into the blood, with an absolute bioavailability of 57%.

What the research says

It blocks histamine at the H1 receptor, which is what stops the itch. For itchy allergic eyes the evidence is solid and consistent: a meta-analysis of randomised trials found a pooled mean difference in ocular itch of -1.33 against placebo. For hay fever the nasal spray beats its vehicle, but the margin is modest, and the combination product with mometasone was judged by a Canadian health technology body to add nothing clinically meaningful over mometasone alone. Harms are mostly local and mild, with one that stands out: a bitter taste reported by about one in eight people using the nasal spray against about one in sixty on vehicle.

Evidence grade: Well established.

How it works

Drug class: Histamine H1 receptor antagonist (second-generation antihistamine) with mast-cell mediator-release inhibition

Olopatadine blocks the histamine H1 receptor, the receptor through which histamine released by allergen-triggered mast cells causes itch, redness, swelling and runny nose. The label states the antihistaminic activity has been shown in isolated tissues, animal models and humans. A clinical trial report adds that olopatadine also inhibits the release of proinflammatory mediators from human mast cells, which is why it is sometimes described as a dual-acting agent rather than a pure antihistamine. (Source 1)

What it is used for

• A systematic review and meta-analysis of randomised trials found topical olopatadine better than placebo for ocular itch, with a pooled mean difference of -1.33, and for conjunctival hyperaemia, pooled mean difference -0.92, both p < 0.00001. A conjunctival allergen challenge trial of the once-daily 0.2% strength in ninety subjects found it significantly better than placebo for itching at every time point. Evidence: established. (Source 2)
• A phase III trial in 544 patients found mean reductions from baseline in reflective total nasal symptom score of 26.8% with olopatadine nasal spray against 18.4% with the identical inactive vehicle (P = 0.003), and non-inferiority to azelastine. The benefit is real but modest, and the absolute difference against vehicle was about 8 percentage points of symptom score reduction. Evidence: established. (Source 3)
• In a trial programme including 1188 children, olopatadine nasal spray at one or two sprays per nostril twice daily was superior to vehicle for the percent decrease in reflective total nasal symptom scores, and the one-spray dose was also superior for ocular symptoms and quality of life. The reported p values are thresholds rather than effect sizes, so the size of the benefit is not clear from the abstract. Evidence: limited. (Source 4)
• The combination beat placebo in a 1176-patient trial, with a least squares mean difference in nasal symptom score of -1.09, and also beat each single agent. But Canada's Drug Agency recommended against reimbursing it, because compared with mometasone nasal spray alone the improvements were not clinically meaningful in adolescents and adults and there was no comparative evidence in children. Evidence: mixed. (Source 5)
• Oral olopatadine is not marketed in the United States, so this use is off-label there and unavailable in practice. A single-centre randomised double-blind trial in 60 patients found it reduced wheal counts, wheal size and total symptom score more than rupatadine, with fewer adverse effects. One small single-centre trial against an active comparator is not a literature. Evidence: limited. (Source 6)

Interactions

• Alcohol (label): The nasal spray label says to avoid alcohol while using it, because the two together can reduce alertness and impair central nervous system performance more than either alone. This is a label caution based on the drug's class and the somnolence seen in trials, not on a dedicated interaction study. (Source 7)
• Other central nervous system depressants (label): Same caution as for alcohol: sedating medicines taken alongside the nasal spray can add to its drowsiness and impair performance. (Source 7)
• Liver enzyme inhibitors and drugs competing for plasma protein binding (label): No formal interaction studies were done. Because olopatadine is cleared mainly unchanged by the kidneys rather than metabolised by liver enzymes, the label says interactions of this kind are not expected. That is reasoning from pharmacology, not a measurement. (Source 8)
• Other eye drops used at the same time (label): The over-the-counter eye drop label asks for a five-minute gap between products so one does not wash the other out, and for contact lenses to be removed before use. (Source 9)

Stopping it

• No dependence, withdrawal or rebound syndrome for olopatadine appears in the literature reached here. It is treated as a symptomatic medicine that can simply be stopped. The over-the-counter eye drop label sets a time limit on self-treatment instead of a taper. (Source 9)
• For the nasal spray, the stopping rule in the label is harm-driven: treatment is to be discontinued if nasal ulceration or perforation appears, and the nasal mucosa should be checked periodically. (Source 10)

What goes wrong

Bitter taste is the standout adverse effect of the nasal spray, affecting about one patient in eight against about one in sixty on vehicle. (Source 3)

• Randomized trial, Moderate certainty.
• Size: 544 patients; 180 on olopatadine, 188 on azelastine, 176 on vehicle.
• Who: Patients aged 12 and older with seasonal allergic rhinitis.
• How long: 16 days of twice-daily dosing.
• Result: Bitter taste in 12.2% (22/180) on olopatadine, 19.7% (37/188) on azelastine and 1.7% (3/176) on inactive vehicle. Other treatment-related adverse events including epistaxis and nasal discomfort were 3.7% or less in each group and did not differ significantly.
• Funding: industry-funded.

Limit of this finding: These rates come from the same small 16-day trial, and taste is the one place the two sprays differed: bitter taste was less common and less intense with olopatadine than with azelastine. That is not a finding about olopatadine's symptom relief, which was not significantly different from azelastine's.

The most commonly reported treatment-related AE in the OLO and AZE groups was bitter taste (12.2% [22/180] and 19.7% [37/188], respectively).

Across six placebo-controlled trials, slightly more people stopped the nasal spray for adverse reactions than stopped vehicle. (Source 11)

• Official position, Certainty not rated.
• Size: 1,834 adults and adolescents on olopatadine nasal spray; 1,844 on 3.7 pH vehicle; 342 on 7.0 pH vehicle.
• Who: Patients 12 years of age and older with seasonal or perennial allergic rhinitis.
• How long: Trials of 2 weeks to 1 year.
• Result: Discontinuation for adverse reactions in 4.7% of 1,834 olopatadine patients, 3.5% of 1,844 patients on 3.7 pH vehicle and 2.9% of 342 patients on 7.0 pH vehicle. The label calls the incidence comparable.
• Funding: not applicable.

Overall, 4.7% of the 1,834 adult and adolescent patients across all 6 studies treated with olopatadine hydrochloride nasal spray, 3.5% of the 1,844 patients treated with 3.7 pH vehicle nasal spray discontinued due to adverse reactions

Nasal septal perforation has been reported in long-term safety trials, but it occurred on vehicle as well as on drug. (Source 12)

• Official position, Certainty not rated.
• Size: Three placebo-controlled 12-month safety trials.
• Who: Patients on olopatadine nasal spray or vehicle nasal spray for 12 months.
• How long: 12 months.
• Result: In the first trial, perforation in one patient on an investigational olopatadine formulation containing povidone and 2 patients on the povidone vehicle. In the second trial, using the marketed formulation, no perforations. In the third, one patient on the 3.7 pH vehicle reported a perforation.
• Funding: not applicable.

Nasal septal perforations were reported in one patient treated with the investigational formulation of olopatadine hydrochloride nasal spray and 2 patients treated with the vehicle nasal spray.

Somnolence has been reported with the nasal spray, which is why the label warns against hazardous tasks and against alcohol. (Source 7)

• Official position, Certainty not rated.
• Size: Not applicable; regulatory warning text drawn from the clinical trials.
• Who: Patients using olopatadine hydrochloride nasal spray.
• How long: Throughout treatment.
• Result: No rate is given in this section. The label instructs caution about driving or operating machinery and says concurrent alcohol or other central nervous system depressants should be avoided.
• Funding: not applicable.

In clinical trials, the occurrence of somnolence has been reported in some patients taking olopatadine hydrochloride nasal spray

Olopatadine nasal monotherapy produced more treatment-emergent adverse events than placebo in the combination trial. (Source 5)

• Randomized trial, Moderate certainty.
• Size: 1176 patients across four arms.
• Who: Patients aged 12 years or older with seasonal allergic rhinitis.
• How long: 14 days.
• Result: Treatment-emergent adverse events in 12.6% of the olopatadine arm against 9.5% of the placebo arm, a difference of about three percentage points; the combination arm was highest at 15.6%.
• Funding: industry-funded.

Treatment-emergent AEs occurred in 15.6%, 12.6%, 9.6%, and 9.5% of patients in the GSP301, olopatadine, mometasone, and placebo groups, respectively.

Bad or bitter taste and nosebleeds were the commonest treatment-related effects in children given the nasal spray. (Source 4)

• Randomized trial, Low certainty.
• Size: 1188 subjects in study 1 (ages 6 to under 12) and 132 in study 2 (ages 2 to under 6)
• Who: Children with seasonal allergic rhinitis or allergic rhinitis.
• How long: Not stated in the abstract.
• Result: No rates are given in the abstract. The commonest treatment-related events in the olopatadine group were bad or bitter taste and epistaxis; the abstract reports an overall low rate of adverse events and low systemic exposure in children aged 2 to under 12.
• Funding: industry-funded.

Limit of this finding: The paper's own first sentence says the 0.6% nasal spray is indicated for people aged 12 and over, so these two studies describe use in children below the age range on the product's label at the time. The abstract gives p values but not the size of the benefit, so how much better than the vehicle it was cannot be judged from it, and it gives no adverse-event rates - only which events were commonest.

The most frequently reported treatment-related events in the OLO group were bad/bitter taste and epistaxis.

What the evidence supports

Topical olopatadine reduced ocular itch and redness more than placebo across randomised trials. (Source 2)

• Meta-analysis, Moderate certainty.
• Size: Randomised controlled trials in patients with allergic conjunctivitis; the abstract does not give a pooled participant total.
• Who: Patients with allergic conjunctivitis.
• How long: Not stated in the abstract.
• Result: Pooled mean difference in ocular itch -1.33 (p < 0.00001) and in ocular hyperemia -0.92 (p < 0.00001) against placebo.
• Funding: not stated.

When compared with placebo, topical olopatadine is associated with a pooled-mean difference (MD) in ocular itch of -1.33 (p < 0.00001) and ocular hyperemia of -0.92 (p < 0.00001).

Once-daily olopatadine 0.2% eye drops beat placebo for itching, redness, chemosis and eyelid swelling in a conjunctival allergen challenge trial. (Source 13)

• Randomized trial, Low certainty.
• Size: Ninety subjects evaluated.
• Who: Subjects with a history of allergic conjunctivitis, randomised by eye.
• How long: Four visits over a 5-week period; challenges at onset of action and at 16 hours.
• Result: Significantly more effective than placebo for ocular itching at all time points (p < 0.001) and for conjunctival redness, chemosis and eyelid swelling (p < 0.03), with redness significant at five of six time points.
• Funding: industry-funded (the product is identified in the abstract as Pataday, Alcon)

Limit of this finding: Two things about this abstract. First, its own description of the study is internally inconsistent: it says the drug was assessed "at onset of action (visit 4) and 16 hours (visit 3)", which puts visit 4 before visit 3. The numbering is the journal's and cannot be resolved from the abstract, so it has been left as printed. Second, the itch was provoked in a clinic by conjunctival allergen challenge rather than by natural pollen exposure, and the product is identified in the abstract as Pataday, Alcon, with Alcon-affiliated authors, so this is the manufacturer testing its own product.

Olopatadine 0.2% was significantly (p < 0.001) more effective than placebo in the treatment of ocular itching at all time points at both the onset of action and the 16-hour allergen challenges.

Olopatadine nasal spray reduced nasal symptom scores more than its inactive vehicle in seasonal allergic rhinitis. (Source 3)

• Randomized trial, Moderate certainty.
• Size: 544 patients randomised at 21 US centres.
• Who: Patients aged 12 years or older with a history of seasonal allergic rhinitis and verified allergy to a prevalent local allergen; mean age 36 years.
• How long: 2 sprays in each nostril twice daily for 16 days.
• Result: Mean reductions from baseline in reflective total nasal symptom score of 26.8% with olopatadine, 29.9% with azelastine and 18.4% with inactive vehicle (P = 0.003 olopatadine versus vehicle; 95% CI -2.5% to 8.7% versus azelastine for non-inferiority)
• Funding: industry-funded (a phase III programme for the intranasal formulation)

Limit of this finding: The authors call this "this small study" in their own conclusions. Olopatadine beat the inactive vehicle, but it was not shown to be better than azelastine: that comparison was a non-inferiority test and the difference between the two sprays was not statistically significant. Nothing here makes olopatadine the stronger of the two sprays.

The mean reductions from baseline in reflective TNSS were 26.8%, 29.9%, and 18.4% with OLO, AZE, and inactive vehicle, respectively (P = 0.003 OLO vs inactive vehicle; 95% CI, -2.5% to 8.7% OLO vs AZE [non-inferiority]).

Adding olopatadine to mometasone in one nasal spray improved nasal symptoms over placebo and over either single agent. (Source 5)

• Randomized trial, Moderate certainty.
• Size: 1176 patients randomised 1:1:1:1.
• Who: Patients aged 12 years or older with seasonal allergic rhinitis.
• How long: 14 days of twice-daily treatment.
• Result: Reflective total nasal symptom score least squares mean difference versus placebo -1.09 (95% CI -1.49 to -0.69; P < .001), versus olopatadine P = .03 and versus mometasone P = .02. Treatment-emergent adverse events in 15.6% on the combination, 12.6% on olopatadine, 9.6% on mometasone and 9.5% on placebo.
• Funding: industry-funded (GSP301 development programme)

GSP301 provided statistically significant and clinically meaningful rTNSS improvements vs placebo (least squares mean difference, -1.09; 95% CI, -1.49 to -0.69; P < .001) and vs olopatadine (P = .03) and mometasone (P = .02).

Olopatadine nasal spray is absorbed into the bloodstream, so it is not a purely local treatment. (Source 14)

• Blood level study, Moderate certainty.
• Size: Healthy subjects and seasonal allergic rhinitis patients; numbers not given in the quoted section.
• Who: Healthy volunteers and patients with seasonal allergic rhinitis on twice-daily intranasal dosing.
• How long: To steady state on twice-daily dosing.
• Result: Mean steady-state peak plasma concentration 16 ± 8.99 ng/mL in healthy subjects with AUC 0-12 averaging 66 ± 26.8 ng·h/mL; in rhinitis patients mean steady-state Cmax 23.3 ± 6.2 ng/mL and AUC 0-12 averaging 78 ± 13.9 ng·h/mL. Absolute bioavailability of intranasal olopatadine is 57%.
• Funding: not applicable.

The average absolute bioavailability of intranasal olopatadine is 57%.

In a small single-centre trial, oral olopatadine reduced chronic urticaria symptoms more than rupatadine. (Source 6)

• Randomized trial, Very low certainty.
• Size: 60 patients recruited and randomised to two groups.
• Who: Patients with chronic spontaneous urticaria at a single centre.
• How long: 6 weeks.
• Result: Greater reduction with olopatadine in mean total symptom score (p = 0.01), number of wheals (P < 0.05), size of wheals (p < 0.05), intensity of erythema (p < 0.05) and eosinophil count (p = 0.015). Adverse effects were fewer in the olopatadine group.
• Funding: not stated.

Limit of this finding: Two of the outcomes in this result sentence, intensity of erythema and change in eosinophil count, are not among the measures the abstract's own methods section says were assessed, so they were not stated in advance; a p value for an outcome chosen after the fact is much weaker than one that was planned. The trial randomised 60 patients at a single centre, about half in each group, which is far too few to settle which of the two antihistamines is better. "eosinopils" is the source's own spelling and has been left as printed.

In olopatadine group, there was significantly higher reduction in MTSS (p = 0.01), Number of wheals (P < 0.05), Size of wheals (p < 0.05), Scale for intensity of erythema (p < 0.05) and change in eosinopils count (p = 0.015) than that of rupatadine.

What the evidence does not support

In a conjunctival allergen challenge model, olopatadine 0.2% relieved provoked ocular itch less well than alcaftadine 0.25%, although both beat placebo. (Source 15)

• Meta-analysis, Moderate certainty.
• Size: 284 subjects across two pooled studies.
• Who: Subjects in the conjunctival allergen challenge model of allergic conjunctivitis.
• How long: Primary measure at 3 min post-challenge, 16 h after instillation.
• Result: Mean itch score 0.50 with alcaftadine versus 0.87 with olopatadine (P=0.0006); over all time points 0.68 versus 0.92 (P=0.0390); both better than placebo at 2.10 (P<0.0001). Minimal itch over all time points in 76.1% versus 58.1% (P=0.0121)
• Funding: industry-funded (a pooled analysis of the alcaftadine development programme)

Limit of this finding: The itching here was provoked on purpose in a clinic using the conjunctival allergen challenge model, not by ordinary pollen exposure, so these scores are not a measure of how either drop performs through a real allergy day. "16 h after treatment instillation" is the gap between putting the drop in and that single provoked challenge; it is not a measured 16 hours of relief. The analysis pools two trials of the comparator product and favours it, so read it as the alcaftadine programme's own evidence rather than as an independent comparison.

At 3 min post-CAC and 16 h after treatment instillation, alcaftadine 0.25% achieved a significantly lower mean itch score compared with olopatadine 0.2% (0.50 vs. 0.87, respectively; P=0.0006).

Canada's Drug Agency recommended against public reimbursement of the olopatadine-mometasone combination spray, judging that it added nothing clinically meaningful over mometasone alone. (Source 16)

• Official position, Certainty not rated.
• Size: Three clinical trials reviewed, two in adolescents and adults and one in children.
• Who: Adults, adolescents and children with moderate-to-severe seasonal allergic rhinitis.
• How long: Not stated.
• Result: No numbers are given. The committee concluded the improvements against mometasone nasal spray were not clinically meaningful in adolescents and adults, with no comparative evidence in children, and recommended against public reimbursement.
• Funding: public reimbursement review by Canada's Drug Agency (CDA-AMC); finding made by the Canadian Drug Expert Committee (CDEC)

Limit of this finding: This is a reimbursement decision, not a clinical trial, and its headline is negative: CDA-AMC recommended that the combination should not be paid for by public drug plans. The committee also said it could not tell whether the product met any unmet need, because the evidence against appropriate active comparators was too uncertain, and there was no comparative evidence at all in children. A recommendation about public funding in one country is not the same as a judgement that a drug does not work.

However, compared to mometasone nasal spray, the improvements were not clinically meaningful in adolescents and adults, and there was no comparative evidence available in children.

Where the research disagrees

Whether olopatadine is as good as newer topical antihistamines for ocular itch

• Meta-analysis authors (2017), systematic review and meta-analysis of randomised trials: Topical olopatadine is a safe and effective treatment modality for allergic conjunctivitis, whereas alcaftadine appears to be superior to olopatadine in reducing ocular itch. (Source 2)
• Pooled analysis of two alcaftadine trials (2014), pooled analysis of two conjunctival allergen challenge trials, 284 subjects, industry-funded: Alcaftadine and olopatadine both provided effective relief compared with placebo and were generally well tolerated. (Source 15)

Whether adding olopatadine to a nasal steroid is worth it

• GSP301 trial investigators (2019), randomised double-blind four-arm trial, 1176 patients, industry-funded: GSP301 provided statistically significant and clinically meaningful rTNSS improvements vs placebo (least squares mean difference, -1.09; 95% CI, -1.49 to -0.69; P < .001) and vs olopatadine (P = .03) and mometasone (P = .02). (Source 5)
• Canada's Drug Agency expert committee (2025), reimbursement recommendation by Canada's Drug Agency (CDA-AMC) / Canadian Drug Expert Committee (CDEC), based on three clinical trials plus indirect comparisons; the recommendation was against public reimbursement: However, compared to mometasone nasal spray, the improvements were not clinically meaningful in adolescents and adults, and there was no comparative evidence available in children. (Source 16)

How much

• Reference intake: Dosing is set by the prescriber for the nasal spray and printed on the carton for the over-the-counter drops. The US nasal spray label (effective 2026-09-15) gives two sprays per nostril twice daily for adults and adolescents 12 years and over, and one spray per nostril twice daily for children 6 to 11, at 665 mcg of olopatadine hydrochloride per spray. (Source 17)
• Upper limit: For the over-the-counter eye drops the label is explicit: adults and children 2 years of age and older put 1 drop in the affected eye or eyes twice daily, every 6 to 8 hours, no more than twice per day. There is no higher permitted amount and no prescriber-titrated range for the drops. (Source 9)
• Studied: The phase III rhinitis trial used 2 sprays in each nostril twice daily for 16 days of the 0.6% nasal spray. (Source 3)
• Studied: The paediatric programme used 1 or 2 sprays per nostril twice daily in children aged 6 to under 12 and 2 to under 6. (Source 4)
• Studied: The conjunctival allergen challenge trial used olopatadine hydrochloride ophthalmic solution 0.2% once daily. (Source 13)
• Studied: The combination trial used twice-daily olopatadine 665 mcg, with or without mometasone 25 mcg, for 14 days. (Source 5)
• Studied: The chronic urticaria trial used oral olopatadine over 6 weeks against rupatadine. (Source 6)

A common belief, and what the research shows

The belief: Antihistamine eye drops and nasal sprays act only where you put them, so they cannot make you drowsy.

What the research shows: The nasal spray's label reports somnolence in clinical trials, warns against driving or operating machinery after a dose, and says to avoid alcohol and other central nervous system depressants. The pharmacokinetic data explain why: the average absolute bioavailability of intranasal olopatadine is 57%, so a measurable amount reaches the bloodstream.

Questions and answers

What is it?

A second-generation antihistamine. In the United States you will meet it as over-the-counter allergy eye drops, as a prescription nasal spray for hay fever, or combined with a steroid in one nasal spray. It is not a nutrient and the body does not make it. (Source 18)

What does it do in the body?

It sits on the histamine H1 receptor and blocks it, so the histamine released when pollen or dander triggers mast cells cannot deliver its message. That is what stops the itching, and the knock-on redness, swelling and runny nose. (Source 1)

Is it good or bad for you?

Useful for allergy symptoms, with mostly minor costs. A meta-analysis of randomised trials found topical olopatadine better than placebo for ocular itch, and the nasal spray beats its vehicle for nasal symptoms. The main nuisance is taste: about 12.2% of nasal spray users reported a bitter taste against 1.7% on the inactive vehicle. It is not disease-modifying; it treats symptoms while you take it. (Source 3)

How do you get more of it?

The amount is set by the label or by a prescriber, not by anything you eat. The nasal spray is two sprays per nostril twice daily for anyone 12 or older, one spray per nostril twice daily for children aged 6 to 11, at 665 mcg per spray. The eye drops are one drop twice daily. (Source 17)

If it is harmful, what reduces it?

You stop using it. There is no antidote or binding agent described, and no taper. For the eye drops the label gives explicit stop signals: eye pain, changes in vision, more redness, or itching that worsens or lasts beyond 72 hours. (Source 9)

Why might someone be low in it or missing it?

This question does not apply as written: olopatadine is not something the body holds a store of, so nobody is low in it. The nearest real question is why someone might be getting less drug than intended, and the label's answer is technical rather than biological: the device has to be primed before first use and re-primed if it has not been used for more than seven days, or the dose cannot be assured. (Source 17)

Which whole foods contain it or feed it?

None. No whole food contains olopatadine or feeds it; it is a manufactured medicine. The over-the-counter drops list what is actually in the bottle: olopatadine 0.1% plus benzalkonium chloride, phosphate buffer, saline and water. (Source 9)

What happens if you do not have it?

Nothing happens to the body itself, because it is not a nutrient. What happens is that allergy symptoms go untreated. The placebo and vehicle arms of the trials show the size of that: nasal symptom scores fell 18.4% on inactive vehicle against 26.8% on olopatadine, so roughly a third of the symptom relief in the trial was attributable to the drug. (Source 3)

How can you test for it?

There is no clinical test for olopatadine status and no routine blood-level monitoring. Plasma concentrations have been measured in pharmacokinetic studies, where steady-state peaks after intranasal dosing averaged 16 ± 8.99 ng/mL in healthy subjects and 23.3 ± 6.2 ng/mL in rhinitis patients, but these are research measurements, not a clinical test anyone would order. (Source 14)

References

1. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: moa [label effective date 2026-09-15]. 2026. Read the source
2. Ocular immunology and inflammation. Topical Olopatadine in the Treatment of Allergic Conjunctivitis: A Systematic Review and Meta-analysis.. 2017. PMID 27192186, DOI 10.3109/09273948.2016.1158282. Read the source
3. Clinical therapeutics. Effects of olopatadine hydrochloride nasal spray 0.6% in the treatment of seasonal allergic rhinitis: a phase III, multicenter, randomized, double-blind, active- and placebo-controlled study in adolescents and adults.. 2009. PMID 19243710, DOI 10.1016/j.clinthera.2009.01.016. Read the source
4. Allergy and asthma proceedings. Safety and efficacy of olopatadine hydrochloride nasal spray 0.6% in pediatric subjects with allergic rhinitis.. 2009. PMID 20031007, DOI 10.2500/aap.2009.30.3298. Read the source
5. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology. Efficacy and safety of olopatadine-mometasone combination nasal spray for the treatment of seasonal allergic rhinitis.. 2019. PMID 30910440, DOI 10.1016/j.anai.2019.03.017. Read the source
6. Indian journal of dermatology. Comparison of Efficacy, Safety and Cost-effectiveness of Rupatadine and Olopatadine in Patients of Chronic Spontaneous Urticaria: A Randomized, Double-blind, Comparative, Parallel Group Trial.. 2016. PMID 26955097, DOI 10.4103/0019-5154.159621. Read the source
7. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: somnolence [label effective date 2026-09-15]. 2026. Read the source
8. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: dix [label effective date 2026-09-15]. 2026. Read the source
9. DailyMed (US National Library of Medicine) / Alcon Laboratories, Inc.. PATADAY TWICE A DAY RELIEF (olopatadine hydrochloride 0.1%) ophthalmic solution - OTC Drug Facts label - section: otc [label effective date 2026-01-20]. 2026. Read the source
10. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: wp [label effective date 2026-09-15]. 2026. Read the source
11. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: ae [label effective date 2026-09-15]. 2026. Read the source
12. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: perf [label effective date 2026-09-15]. 2026. Read the source
13. Allergy and asthma proceedings. Efficacy of olopatadine ophthalmic solution 0.2% in reducing signs and symptoms of allergic conjunctivitis.. 2007. PMID 17883910, DOI 10.2500/aap.2007.28.3014. Read the source
14. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: pk [label effective date 2026-09-15]. 2026. Read the source
15. Advances in therapy. Ocular itch relief with alcaftadine 0.25% versus olopatadine 0.2% in allergic conjunctivitis: pooled analysis of two multicenter randomized clinical trials.. 2014. PMID 25260889, DOI 10.1007/s12325-014-0155-3. Read the source
16. Canada's Drug Agency (CDA-AMC), Canadian Drug Expert Committee (CDEC). Olopatadine Hydrochloride and Mometasone Furoate Nasal Spray (Ryaltris): Indication: For the symptomatic treatment of moderate to severe seasonal allergic rhinitis and associated ocular symptoms in adults, adolescents, and children aged 6 years and older: Reimbursement Recommendation. 2025. PMID 40424422. Read the source
17. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Full Prescribing Information (section quoted below) - section: dose [label effective date 2026-09-15]. 2026. Read the source
18. DailyMed (US National Library of Medicine) / Apotex Corp.. Olopatadine Hydrochloride Nasal Spray - Highlights of Prescribing Information (section quoted below) - section: INDICATIONS AND USAGE [label effective date 2026-09-15]. 2026. Read the source