What Cannot Be Taken With Losartan: A Guide to Major Drug and Food Interactions

October 13, 2025 •

4 min read

Losartan is one of the most commonly prescribed medications for high blood pressure in the US, but it requires careful attention to potential drug and food interactions. Understanding what cannot be taken with losartan is crucial for patients and healthcare providers alike to prevent dangerous side effects, such as dangerously high potassium levels (hyperkalemia) or kidney problems.

Quick Summary

Dangerous losartan interactions include combinations with potassium supplements, NSAIDs, other renin-angiotensin system blockers, and lithium. Certain foods and alcohol also require caution.

Key Points

Potassium Sources: Avoid potassium supplements, potassium-sparing diuretics, and potassium-containing salt substitutes to prevent dangerous hyperkalemia.
NSAID Caution: Be cautious with NSAIDs like ibuprofen, which can reduce losartan's effectiveness and increase the risk of kidney problems, especially with chronic use.
Dual Blockade Alert: Never combine losartan with ACE inhibitors (e.g., lisinopril) or the direct renin inhibitor aliskiren due to a high risk of adverse effects.
Monitor Lithium Levels: Losartan can cause lithium levels to rise, potentially leading to toxicity, so regular monitoring is required.
Grapefruit and Alcohol: Limit or avoid grapefruit products and alcohol consumption, as they can interfere with losartan's action and increase the risk of side effects like low blood pressure.
Herbal Supplements: Always discuss any herbal remedies with your doctor, as some can impact blood pressure or potassium levels.

For many individuals managing high blood pressure, heart failure, or kidney disease related to diabetes, losartan is a crucial part of their treatment plan. This angiotensin II receptor blocker (ARB) works by relaxing blood vessels, which lowers blood pressure and improves blood flow. However, its mechanism of action also makes it susceptible to significant interactions with other drugs and even certain foods. Ignoring these potential interactions could compromise the medication's effectiveness or lead to serious health complications.

Medications with Major Interaction Risks

When a healthcare provider prescribes losartan, it is imperative to disclose all other medications, including over-the-counter (OTC) products, vitamins, and supplements. Several classes of drugs pose a high risk of interaction, necessitating either avoidance or close medical supervision.

Potassium-Related Medications

One of the most significant concerns with losartan is its effect on potassium levels. Losartan can increase blood potassium levels, a condition called hyperkalemia. Combining it with other substances that also raise potassium can lead to serious and even life-threatening cardiac complications.

Potassium Supplements: Patients should not take prescription or over-the-counter potassium supplements unless specifically instructed by a doctor.
Potassium-Sparing Diuretics: These 'water pills' are designed to increase fluid excretion while retaining potassium. Taking them with losartan significantly heightens the risk of hyperkalemia. Examples include spironolactone (Aldactone), triamterene (Dyrenium), and eplerenone (Inspra).
Potassium-Containing Salt Substitutes: Many salt substitutes replace sodium with potassium. This extra potassium intake can be dangerous for someone on losartan and should be avoided.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

For patients on losartan, common NSAID pain relievers carry significant risks. While occasionally used together with close monitoring, frequent or chronic use is particularly concerning.

Decreased Efficacy: NSAIDs like ibuprofen (Advil, Motrin), naproxen (Aleve), and aspirin (at high doses) can counteract the blood pressure-lowering effects of losartan.
Increased Kidney Damage Risk: The combination of losartan and an NSAID, especially in older patients or those with pre-existing kidney issues or dehydration, can increase the risk of kidney function decline or acute kidney injury.

Other Renin-Angiotensin System (RAS) Blockers

Combining losartan with other drugs that target the RAS, the very system losartan is meant to regulate, is a major contraindication.

ACE Inhibitors: The combination of losartan with an ACE inhibitor (e.g., lisinopril, enalapril) should be avoided due to an increased risk of severe hypotension, hyperkalemia, and kidney problems.
Aliskiren (Tekturna): This direct renin inhibitor should not be used with losartan, particularly in patients with diabetes or kidney disease.
Entresto (Sacubitril/Valsartan): As a combination drug containing another ARB (valsartan), it should not be taken with losartan.

Lithium

Losartan can interfere with the body's ability to excrete lithium, a medication used to treat bipolar disorder and other mental health conditions. This can lead to a dangerous buildup of lithium in the body, causing potentially life-threatening lithium toxicity. Symptoms can include tremors, confusion, and vomiting.

Food, Supplement, and Lifestyle Considerations

Beyond prescription drugs, certain dietary choices and habits can influence losartan's safety and effectiveness.

Grapefruit and Grapefruit Juice

Some studies suggest that grapefruit and grapefruit juice can inhibit an enzyme involved in breaking down losartan in the intestinal tract. This could potentially affect the medication's absorption and efficacy, although the evidence is sometimes contradictory. Most healthcare providers recommend limiting or avoiding grapefruit products.

Alcohol

While no direct chemical interaction is known, alcohol consumption can increase the risk of side effects like dizziness and low blood pressure when taking losartan. It is best to avoid or limit alcohol intake, particularly when first starting the medication or following a dose increase.

Herbal Supplements

Certain herbal products can interact with losartan. Chicory, ginseng, and mugwort are some examples that may contain potassium or have diuretic properties. Patients should always consult a doctor or pharmacist before taking any herbal remedies or supplements alongside losartan.

Potential Drug and Food Interactions with Losartan


Interaction Type	Common Examples	Potential Risk	Management
Potassium Supplements & Salt Substitutes	Potassium chloride (Klor-Con), No Salt brand substitutes	Hyperkalemia (high blood potassium) leading to irregular heartbeat, weakness	Avoid unless medically necessary; Monitor potassium levels.
NSAIDs	Ibuprofen (Advil), Naproxen (Aleve), high-dose Aspirin	Reduced losartan effectiveness, kidney damage	Consider alternatives; Frequent kidney function and blood pressure monitoring.
ACE Inhibitors & Aliskiren	Lisinopril, enalapril, aliskiren (Tekturna)	Severe hypotension, hyperkalemia, kidney failure (dual blockade)	Avoid combination; Never combine without explicit medical instruction.
Lithium	Lithium carbonate (Lithobid)	Lithium toxicity due to increased lithium levels in blood	Close monitoring of lithium levels required; Dose adjustments may be needed.
Grapefruit & Grapefruit Juice	Fresh grapefruit, grapefruit juice	Decreased losartan effectiveness due to altered metabolism	Limit or avoid consumption, particularly if efficacy is in question.
Alcohol	Beer, wine, liquor	Increased risk of low blood pressure (hypotension), dizziness	Limit or avoid intake, especially during dose changes.

Navigating Your Losartan Treatment Safely

For patients taking losartan, proactive communication with your healthcare team is your best defense against harmful interactions. Before starting a new medication—whether prescription, OTC, or herbal—always check for potential conflicts. Be mindful of your diet and lifestyle choices, particularly concerning potassium and alcohol. It is also important to recognize the symptoms of an interaction, such as dizziness, muscle weakness, or a very fast or irregular heartbeat, and report them to your doctor immediately. By staying informed and vigilant, you can ensure your treatment is as safe and effective as possible.

Conclusion

Understanding what cannot be taken with losartan is a critical step for anyone on this medication. The most dangerous interactions involve substances that significantly increase potassium levels, interfere with kidney function, or target the same blood pressure-regulating pathways. By avoiding potassium supplements and salt substitutes, managing NSAID use, and never combining losartan with other RAS blockers like ACE inhibitors or aliskiren, patients can mitigate serious risks. Regular communication with your doctor about all drugs, supplements, and dietary habits ensures a safe and effective treatment regimen. For further information on losartan and drug safety, consult authoritative sources like the U.S. Food and Drug Administration (FDA).

Frequently Asked Questions

It is generally not recommended to take NSAIDs like ibuprofen or naproxen with losartan, particularly for chronic pain. The combination can reduce the effectiveness of losartan and increase the risk of kidney damage. Your doctor may suggest safer alternative pain relief options.

Combining potassium supplements with losartan can lead to dangerously high levels of potassium in the blood, a condition called hyperkalemia. This can cause serious cardiac problems, including an irregular heartbeat. You should avoid these supplements unless your doctor specifically advises otherwise.

While it is not necessary for most people to avoid potassium-rich foods like bananas, individuals with existing kidney problems should exercise caution. Losartan can raise potassium levels, so excessive intake of high-potassium foods could be a concern. Consult your doctor or pharmacist for personalized dietary advice.

There is no known chemical interaction between losartan and alcohol, but both can cause dizziness and low blood pressure. Combining them may worsen these side effects. It is best to avoid or limit alcohol intake, especially when you first start taking the medication.

No, you should avoid salt substitutes unless instructed by your doctor. Many of these products use potassium chloride as a replacement for sodium chloride, which can cause dangerously high potassium levels when combined with losartan.

You should not take losartan with other medications that block the renin-angiotensin system, including ACE inhibitors (e.g., lisinopril, enalapril) or the direct renin inhibitor aliskiren. Combining them creates a 'dual blockade' that increases the risk of hypotension, hyperkalemia, and kidney issues.

Symptoms of a serious interaction can vary but may include severe dizziness, weakness, muscle cramps, heart palpitations, or signs of kidney problems like decreased urination or swelling. If you experience any of these symptoms, seek immediate medical attention.