What the label lists and what reports show
Dorzolamide and timolol side effects
Dorzolamide and timolol's FDA label: “The most frequently reported adverse reactions were taste perversion (bitter, sour, or unusual taste) or ocular burning and/or stinging in up to 30% of patients.” FAERS holds 8,525 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is eye irritation (808 reports).
- Generic listed
Check it at the source: the dorzolamide and timolol FDA label on DailyMed (effective May 13, 2026, Thea Pharma Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of COSOPT PF?COSOPT PF may cause serious side effects including: • severe breathing problems. These breathing problems can happen in people who have asthma, chronic obstructive pulmonary disease, or heart failure and can cause death. Tell your healthcare provider right away if you have breathing problems while taking COSOPT PF. • heart failure. This can happen in people who already have heart failure and in people who have never had heart failure before. Tell your healthcare provider right away if you get any of these symptoms of heart failure while taking COSOPT PF: o shortness of breath o irregular heartbeat (palpitations) o swelling of your ankles or feet o sudden weight gain • severe allergic reactions. These allergic reactions can happen the first time you use COSOPT PF or after you have been using COSOPT PF for a while and may cause death. […]
Source: FDA drug label, Thea Pharma Inc., effective May 13, 2026 (SPL set 535fc801-8c3f-4974-a120-3eff1d5a5062), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most frequently reported adverse reactions were taste perversion (bitter, sour, or unusual taste) or ocular burning and/or stinging in up to 30% of patients.
From the label: adverse reactions, continuedThe most frequently reported adverse reactions were taste perversion (bitter, sour, or unusual taste) or ocular burning and/or stinging in up to 30% of patients. Conjunctival hyperemia, blurred vision, superficial punctate keratitis or eye itching were reported between 5-15% of patients. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Thea Pharma Inc. at 1-833-838-4028 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. COSOPT and COSOPT PF COSOPT and COSOPT PF were evaluated in patients with elevated intraocular pressure treated for open-angle glaucoma or ocular hypertension for up to 15 months. Approximately 5% of all patients discontinued therapy because of adverse reactions. The most frequently reported adverse reactions occurring in up to 30% of patients were taste perversion (bitter, sour, or unusual taste) or ocular burning and/or stinging. The following adverse reactions were reported in 5% to 15% of patients: conjunctival hyperemia, blurred vision, superficial punctate keratitis or eye itching.
Source: FDA drug label, Thea Pharma Inc., effective May 13, 2026 (SPL set 535fc801-8c3f-4974-a120-3eff1d5a5062), via openFDA; the full label on DailyMed
What do FAERS reports show?
8,525 reports list dorzolamide and timolol among the medicines taken, each a report of something that happened, not proof the medicine caused it; 661 are coded as a death and 1,761 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 20 reactions below, 10 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Dorzolamide and timolol: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions