Losartan is an angiotensin receptor blocker (ARB) used mainly for high blood pressure and to protect the kidneys in some people with diabetes. ARBs relax blood vessels so blood flows more easily, which works well but means they can stack with other blood pressure medicines and affect potassium and the kidneys. Knowing the main losartan interactions and side effects helps you take it safely.
Key takeaways about losartan
- Losartan is an ARB that relaxes blood vessels to lower blood pressure.
- It can raise potassium, so be careful with supplements and salt substitutes.
- Regular NSAIDs (ibuprofen, naproxen) can blunt its effect and stress the kidneys.
- Combining it with other blood pressure drugs can drop pressure too far.
- Report dizziness, fainting, or facial/throat swelling to your prescriber.
Losartan interactions to review
Because losartan acts on blood pressure, kidneys, and potassium, several combinations deserve a closer look. Other blood pressure medicines — including ACE inhibitors, diuretics, and the diabetes/heart medicine class known as potassium-sparing drugs — can add to its effect or push potassium higher. Regular use of NSAIDs can reduce how well losartan controls pressure and, together, strain the kidneys. The exact effect depends on your specific products and doses, so ask a pharmacist to check your list.
Side effects and warning signs
- Dizziness or lightheadedness, especially when standing up quickly.
- Tiredness and, less commonly, a dry cough.
- Signs of high potassium: muscle weakness, numbness, or an irregular heartbeat.
- Swelling of the face, lips, tongue, or throat — seek urgent care.
This is not a complete list. Losartan is not used in pregnancy, so tell your prescriber if you are pregnant or planning to be, and make sure they know your kidney history.
How MedSafeScan helps
MedSafeScan lets you keep losartan alongside your other prescriptions, OTC pain relievers, and supplements — including any potassium product or salt substitute — so overlaps are easier to spot and raise with a pharmacist. Treat any interaction result as a starting point for a professional conversation, not a final decision.
MedSafeScan provides informational guidance only and is not a substitute for professional medical advice. Always consult your healthcare provider before making any changes to your medications.
Quick answers
What should you not take with losartan?
Be cautious combining losartan with potassium supplements or salt substitutes that contain potassium, other blood pressure medicines, and regular NSAIDs such as ibuprofen or naproxen, which can reduce its effect and strain the kidneys. The exact risks depend on your full medicine list, so ask a pharmacist to review it.
Can losartan raise potassium levels?
Yes. Like other ARBs, losartan can raise blood potassium. That matters if you also take potassium supplements, certain water pills, or salt substitutes, or if you have kidney problems. Your prescriber may order blood tests to check potassium and kidney function.
What are the common side effects of losartan?
Common effects include dizziness, especially when standing up, tiredness, and sometimes a cough (though ARBs cause cough less often than ACE inhibitors). Report fainting, swelling of the face or throat, or signs of high potassium such as muscle weakness or an irregular heartbeat. Read your product's patient information for the full list.
Sources and further reading
These public resources are provided for background reading. They do not replace advice from your pharmacist, doctor, or other licensed healthcare professional.
- MedlinePlus: Losartan
- MedlinePlus: High Blood Pressure Medicines
- NIH Office of Dietary Supplements: Potassium
Last reviewed: October 4, 2026