What the label lists and what reports show
Hydrochlorothiazide and losartan side effects
Hydrochlorothiazide and losartan's FDA label: “Most common adverse reactions (incidence ≥2% and greater than placebo) are dizziness, upper respiratory infection, cough, and back pain.” FAERS holds 11,546 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 nausea (773 reports).
- Generic listed
- Boxed warning
Check it at the source: the hydrochlorothiazide and losartan FDA label on DailyMed (effective November 26, 2025, Organon LLC); 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 HYZAAR?HYZAAR may cause the following side effects that may be serious: Injury or death of unborn babies. See " What is the most important information I should know about HYZAAR? " Allergic reaction. Symptoms of an allergic reaction are swelling of the face, lips, throat, or tongue and may include severe shortness of breath and/or difficulty breathing. Get emergency medical help right away and stop taking HYZAAR. Low blood pressure (hypotension). Low blood pressure may cause you to feel faint or dizzy. Lie down if you feel faint or dizzy. Call your doctor right away. If you have kidney problems, you may see a worsening in how well your kidneys work. Call your doctor if you get swelling in your feet, ankles, or hands, or unexplained weight gain. A new or worsening condition called systemic lupus erythematosus (Lupus; SLE) Eye problems. […]
Source: FDA drug label, Organon LLC, effective November 26, 2025 (SPL set 4116ccde-2e23-45f4-b12f-6337df877744), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (incidence ≥2% and greater than placebo) are dizziness, upper respiratory infection, cough, and back pain.
From the label: adverse reactions, continuedMost common adverse reactions (incidence ≥2% and greater than placebo) are dizziness, upper respiratory infection, cough, and back pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Organon LLC, a subsidiary of Organon & Co., at 1-844-674-3200 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. Losartan potassium-hydrochlorothiazide has been evaluated for safety in 858 patients treated for essential hypertension and 3889 patients treated for hypertension and left ventricular hypertrophy. Most adverse reactions have been mild and transient in nature and have not required discontinuation of therapy. In controlled clinical trials, discontinuation of therapy due to clinical adverse events was required in only 2.8% and 2.3% of patients treated with the combination and placebo, respectively. In these double-blind controlled clinical trials, adverse reactions occurring in greater than 2% of subjects treated with losartan-hydrochlorothiazide and at a greater rate than placebo were: back pain (2.1% vs 0.6%), dizziness (5.7% vs 2.9%), and upper respiratory infection (6.1% vs 4.6%).
Source: FDA drug label, Organon LLC, effective November 26, 2025 (SPL set 4116ccde-2e23-45f4-b12f-6337df877744), via openFDA; the full label on DailyMed
What do FAERS reports show?
11,546 reports list hydrochlorothiazide and losartan among the medicines taken, each a report of something that happened, not proof the medicine caused it; 697 are coded as a death and 4,027 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 22 reactions below, 9 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?
- Hydrochlorothiazide and losartan: 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