Losartan Side Effects are documented on the FDA prescribing label, and reported separately by patients and doctors to the FDA’s adverse event system. This page sets out what the official record actually says about Losartan: what it is approved to treat, what the label warns about, its recall history, and what the reported side effects are — along with what those figures do and do not mean.
- What Losartan Is Prescribed For, and Where Losartan Side Effects Come From
- The FDA Boxed Warning on Losartan
- Warnings Beyond the Common Losartan Side Effects
- Losartan Side Effects Listed on the FDA Label
- Reported Losartan Side Effects in the FDA Database
- Who the Label Says Should Take Extra Care
- Losartan Recall History
- Is Losartan the Subject of Litigation?
- If You Are Worried About Losartan Side Effects
- Frequently Asked Questions
- Official Sources
- Related Guides
Before you read on. Do not stop taking a prescribed medicine, or change how you take it, because of anything you read here. Talk to the prescriber or pharmacist who knows your medical history first.
What Losartan Is Prescribed For, and Where Losartan Side Effects Come From
According to the FDA label, osartan Potassium tablets are an angiotensin II receptor blocker (ARB) indicated for: Treatment of hypertension, to lower blood pressure in adults and children greater than 6 years old. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. ( 1.1 ) Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy. There is evidence that this benefit does not apply to Black patients. […]
Two separate official sources describe losartan side effects. The prescribing label records what was observed in clinical trials, where the drug was compared against a control group. The FDA’s adverse event database records what patients and clinicians have reported since approval, which is a much larger but far less controlled picture. Both appear below, and they answer different questions.
| Active ingredient | Losartan Potassium |
| Brand names on this label | Losartan Potassium |
| How it is given | oral |
| Boxed warning | Yes – see below |
| Recall records | 36 |
| Label last updated | 2026-06-04 |
The FDA has revised this label recently. The label’s own record of recent major changes reads: Warnings and Precautions Hyperkalemia (5.4) 10/2018 A recent revision usually means new safety information was added.
The FDA Boxed Warning on Losartan
This medicine carries a boxed warning
WARNING: FETAL TOXICITY When pregnancy is detected, discontinue losartan Potassium tablets as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus [see Warnings and Precautions (5.1)]. WARNING: FETAL TOXICITY See full prescribing information for complete boxed warning. When pregnancy is detected, discontinue losartan potassium tablets as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. ( 5.1 )
A boxed warning is the most serious warning the FDA requires on a prescription label. It does not mean the medicine should not be used. It means there is a specific risk serious enough that the FDA requires it to appear at the very top of the prescribing information, so that prescribers weigh it deliberately for each patient.
Prescribers see this warning every time they consult the label. If it concerns you, it is a reasonable thing to raise at your next appointment and ask how it applies to your own situation.
Warnings Beyond the Common Losartan Side Effects
The label’s warnings and precautions section describes risks the FDA requires prescribers to weigh. For Losartan it covers: Hypotension: Correct volume or salt depletion prior to administration of losartan potassium tablets. ( 5.2 ) Monitor renal function and potassium in susceptible patients. ( 5.3 , 5.4 ) 5.1 Fetal Toxicity 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. When pregnancy is detected, discontinue losartan potassium tablets as soon as possible [see Use in Specific Populations ( 8.1 )]. 5.2 Hypotension in Volume – or Salt-Depleted Patients In patients with an activated renin-angiotensin system, such as volume- or salt-depleted patients (e.g., those being treated with high doses of diuretics), symptomatic hypotension may occur after initiation of treatment with losartan potassium tablets. […]
These are the risks the FDA has judged significant enough to state formally, and they sit apart from the routine losartan side effects most people ask about. They apply to different patients to very different degrees, which is why the same medicine can be routine for one person and unsuitable for another.
Losartan Side Effects Listed on the FDA Label
The label’s adverse reactions section records what was observed in clinical trials: ost common adverse reactions (incidence ≥2% and greater than placebo) are : dizziness, upper respiratory infection, nasal congestion, and back pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Hetero Labs Limited at 1-866-495-1995 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.
Hypertension Losartan potassium has been evaluated for safety in more than 3300 adult patients treated for essential hypertension and 4058 patients/subjects overall. Over 1200 patients were treated for over 6 months and more than 800 for over one year. […]
Trial data is the most reliable source for how common losartan side effects are, because the people taking the drug were compared against people who were not. A symptom that appeared just as often in the control group is not caused by the medicine.
Reported Losartan Side Effects in the FDA Database
Reported losartan side effects — and what these numbers do not mean
The FDA’s adverse event database holds 206,977 reports mentioning Losartan, of which 132,028 were classified as serious.
Read those numbers carefully. An adverse event report means somebody told the FDA that something happened to a person taking this medicine. It is not a finding that the medicine caused it. Reports are submitted voluntarily by patients, families, doctors and manufacturers; nobody verifies them; and the same event can be reported more than once.
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Report volume tracks how many people take a drug, how new it is, and how much attention it is getting. A widely prescribed medicine will always show more reports than a rarely used one, and reports rise sharply when a drug is in the news or in litigation. A large number here does not mean a drug is dangerous, and a small number does not mean it is safe.
| Most frequently reported | Reports |
|---|---|
| Fatigue | 14,302 |
| Diarrhoea | 11,976 |
| Nausea | 11,753 |
| Dyspnoea | 10,586 |
| Dizziness | 10,097 |
| Headache | 9,701 |
| Pain | 9,027 |
| Arthralgia | 7,714 |
Source: FDA Adverse Event Reporting System (FAERS), retrieved July 2026. Non-clinical reporting categories such as “off label use” have been excluded from the list above because they describe how a drug was used, not something that happened to a patient.
Who the Label Says Should Take Extra Care
Contraindications. The label states that Losartan should not be used in certain situations: osartan potassium tablets are contraindicated: In patients who are hypersensitive to any component of this product. For coadministration with aliskiren in patients with diabetes. Hypersensitivity to any component. ( 4 ) Coadministration with aliskiren in patients with diabetes. ( 4 )
Interactions with other medicines. Agents increasing serum potassium: Risk of hyperkalemia. ( 7.1 ) Lithium: Risk of lithium toxicity. ( 7.2 ) NSAIDs: Increased risk of renal impairment and reduced diuretic, natriuretic, and antihypertensive effects. ( 7.3 ) Dual inhibition of the renin-angiotensin system: Increased risk of renal impairment, hypotension, syncope, and hyperkalemia. […]
Older adults. 8.5 Geriatric Use Of the total number of patients receiving losartan potassium in controlled clinical studies for hypertension, 391 patients (19%) were 65 years and over, while 37 patients (2%) were 75 years and over. In a controlled clinical study for renal protection in type 2 diabetic patients with proteinuria, 248 patients (33%) were 65 years and over. […]
Your pharmacist can check your full medicine list against this in a couple of minutes, including anything bought over the counter, and that check is free.
Losartan Recall History
The FDA enforcement database records 36 recall entries involving Losartan products (36 Class II). A recall almost always concerns specific manufactured batches rather than the medicine itself, and different manufacturers of the same generic drug have separate recall records.
The FDA classifies recalls by how serious the potential consequence is. Class I means a reasonable probability of serious harm or death; Class II means temporary or reversible harm is possible; Class III means the product breaks a regulation but is unlikely to cause harm.
| Date | Class | Recalling firm | Reason |
|---|---|---|---|
| 2024-05-22 | Class II | MACLEODS PHARMA USA, INC | Presence of foreign substance: plastic-like substance. |
| 2023-07-12 | Class II | Strides Pharma Inc. | Presence of Foreign Substance: Presence of a small piece of blue plastic embedded in the tablet. |
| 2022-07-06 | Class II | PD-Rx Pharmaceuticals, Inc. | CGMP Deviations- AZIDO Impurity levels observed to be above acceptable limits |
| 2022-07-06 | Class II | PD-Rx Pharmaceuticals, Inc. | CGMP Deviations- AZIDO Impurity levels observed to be above acceptable limits |
| 2022-07-06 | Class II | PD-Rx Pharmaceuticals, Inc. | CGMP Deviations- AZIDO Impurity levels observed to be above acceptable limits |
If a batch you have was recalled, the pharmacy that dispensed it is the fastest way to find out and to get a replacement. Do not simply stop taking a prescribed medicine because a recall notice exists — the recall may not affect your batch, and stopping can carry its own risk.
Is Losartan the Subject of Litigation?
We are not tracking consolidated federal litigation over Losartan. It is a widely prescribed medicine, and the information on this page is drawn from the FDA label and public safety data rather than from any legal claim.
If You Are Worried About Losartan Side Effects
Concern about losartan side effects is a good reason to have a conversation, and not a reason to act alone. Do not stop taking a prescribed medicine, or change how you take it, because of anything you read here. Talk to the prescriber or pharmacist who knows your medical history first. Stopping some medicines abruptly carries risks of its own, and your prescriber can tell you whether that applies to yours.
Write down what you have noticed and when it started before the appointment. Not everything that happens while taking a medicine is one of its losartan side effects, and a specific account — what changed, when, and how often — is what lets a clinician tell the difference.
You can also report a side effect directly to the FDA through MedWatch. Reports from patients are part of how safety signals are detected, and filing one takes a few minutes.
Frequently Asked Questions
What are the most commonly reported losartan side effects?
In FDA reports, the most frequently mentioned are fatigue, diarrhoea, nausea. The label’s own adverse reactions section, drawn from clinical trials, is the better guide to how common a side effect actually is, because reports to the FDA are not collected in a way that supports rates.
Has Losartan been recalled?
There are 36 recall records for Losartan products, the most recent dated 2024-05-22. Recalls generally affect specific manufactured batches rather than the medicine as a whole. Your pharmacy can tell you whether a batch you have was affected.
Does Losartan have a boxed warning?
Yes. The boxed warning is reproduced above. It is the most serious warning the FDA requires, and it exists so that prescribers weigh a specific risk for each patient rather than overlooking it.
Do the FDA report numbers tell me how common these losartan side effects are?
No. Reports are unverified, anyone can file one, and the total mostly reflects how many people take the medicine and how much attention it is getting. A high count is not evidence of danger, and a low one is not evidence of safety. Clinical trial data on the label is the source that supports rates.
Where can I check losartan side effects for the exact product I have?
DailyMed holds the current FDA label for every marketed product, searchable by the name on your packaging. Different manufacturers and formulations of the same medicine can have slightly different labels, so checking the one you actually have is worth the two minutes.
Official Sources
- DailyMed (National Library of Medicine) — the current FDA prescribing label for every product
- FDA Adverse Event Reporting System dashboard — the public report data summarised above
- FDA recalls and safety alerts — current recall notices
- FDA MedWatch — how to report a side effect yourself
Related Guides
Medical and legal disclaimer. This page summarises publicly available FDA data about Losartan and is general information, not medical advice, and not legal advice. It is not a substitute for the judgement of a clinician who knows your medical history. Nothing here states that Losartan caused any illness or injury in any individual. Adverse event reports are unverified and do not establish causation.
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FDA labels are revised regularly; confirm current information on DailyMed or with your pharmacist. Do not stop taking a prescribed medicine, or change how you take it, because of anything you read here. Talk to the prescriber or pharmacist who knows your medical history first.