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Losartan potassium is a prescription medication commonly used to lower blood pressure in people with hypertension (high blood pressure). While high blood pressure is very dangerous and can cause a range of serious medical complications such as kidney damage and increase your risk of developing a stroke, low blood pressure can be dangerous too. Losartan may drop blood pressure too low, causing side effects. Hypotension (low blood pressure) can cause dizziness or lightheadedness, fainting (syncope), blurred vision, inability to concentrate, cold or clammy skin, and fatigue (AHA, 2016).
Moderate alcohol consumption is generally safe while taking losartan, but it may take time to figure out how the two affect you. Common side effects of losartan include dizziness, low blood pressure, and tiredness. Alcohol may cause similar side effects to losartan, including dizziness (or lightheadedness) and drowsiness. Drinking alcohol while taking losartan may amplify these side effects, making them worse. This combination could potentially cause drowsiness, dizziness, and even fainting (NIH, 2019).
It may be helpful to cut back on alcohol consumption when you’re adjusting the drug and its side effects. This may include when you first start taking losartan and a couple of days after any dosage increase.
What is losartan?
Losartan is a prescription medication used to treat high blood pressure. It belongs to a drug class called angiotensin receptor blockers (ARBs) that also includes the medications valsartan and irbesartan. ARBs are generally used to treat high blood pressure, though losartan is approved by the U.S. Food and Drug Administration (FDA) to treat high blood pressure (hypertension), risk of stroke, and kidney problems from diabetes (diabetic nephropathy). However, it may not be as effective at reducing stroke risk in Black people with high blood pressure and left ventricular hypertrophy (enlarged heart) than it is in other groups of people (DailyMed, 2020).
Losartan may also be used off-label after a heart attack, to help individuals with heart failure who cannot tolerate ACE inhibitors because of the side effects (such as a persistent dry cough known as the ACE-I cough), and to treat non-diabetic kidney disease.
ARBs lower blood pressure by blocking the actions of a hormone called angiotensin II that’s naturally produced by the body (Burnier, 2001). This hormone causes blood vessels to constrict and the same amount of blood has to squeeze through smaller tubes, which leads to increased pressure (similarly to how traffic gets congested when a three-lane highway becomes a two-lane highway). These prescription drugs are used in the treatment of hypertension because they prevent this squeezing (DailyMed, 2020).
Losartan is available as a generic drug or under the brand name Cozaar. It is also available in a combination prescription drug sold under the brand name Hyzaar that uses both losartan and a diuretic called hydrochlorothiazide to treat high blood pressure (U.S. National Library of Medicine, 2018). Losartan tablets are available in 25 mg, 50 mg, and 100 mg, though 50 mg is a standard starting dose.
Potential side effects of losartan
Some of the most common side effects of losartan include dizziness, stuffy nose, back pain, chest pain, diarrhea, high levels of potassium, low blood pressure, low blood sugar, and tiredness (FDA, 2018). It’s possible for losartan to cause a severe allergic reaction, which may include symptoms such as hives, itching, rash, and trouble breathing. Low blood pressure (hypotension) and high blood potassium (hyperkalemia) are other serious possible side effects (Tsunoda, 1993; Palmer, 2004). Hyperkalemia can be mild or serious, potentially causing heart problems such as arrhythmias (irregular heartbeat), muscle weakness, or paralysis (Simon, 2020).
Since high blood levels of potassium can be dangerous, you may need to avoid high-potassium foods when taking ARBs. Past research suggests that high dietary potassium may be safe for people with proper kidney function since the kidneys get rid of any excess (Malta, 2016; Palmer, 2015). Those taking ARBs such as losartan who already have kidney problems such as chronic kidney disease (CKD) may need to limit high-potassium foods such as potatoes, tomatoes, oranges, and bananas, however (Han, 2013).
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If you’ve been told by your healthcare provider to avoid table salt as a means to control your blood pressure, you may have come across salt substitutes in your efforts to make your food a little tastier. Be sure to check the label before you buy or use one. Many of these salt substitutes use potassium chloride, which should be avoided if you need to limit potassium (Han, 2013). You should also avoid potassium supplements. Your healthcare provider may measure the levels of potassium in your blood to decide if you need to limit your potassium intake.
Losartan may also cause serious adverse effects when combined with certain medications. Toxicity may result from combining losartan and lithium, a drug used to treat bipolar disorder. Taking non-steroidal anti-inflammatory drugs (NSAIDs) (such as ibuprofen and naproxen) while on losartan may weaken this antihypertensive drug’s effect. Combining multiple medications that work to lower blood pressure can sometimes lower blood pressure too far, resulting in symptoms such as dizziness or fainting (DailyMed, 2020).
Certain people should not take losartan or use this medication with caution. Since the liver breaks down this prescription medication, people with abnormal liver function may have higher-than-normal levels of losartan in their blood. Lower doses of the medication may be needed for these individuals. Those with renal artery stenosis, narrowing of the artery to the kidney, may worsen kidney function by taking losartan (DailyMed, 2020).
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You should stop taking losartan if you become pregnant as the drug may cause fetal injury or even miscarriage if taken during the final six months (second and third trimester) of pregnancy. You should not breastfeed when taking losartan as the medication may pass into the breast milk (FDA, 2018).
Tell your healthcare provider or pharmacist about what other drugs or over-the-counter supplements you’re taking before starting so they can advise on your specific case. If you plan to undergo an operation, tell your healthcare provider that you are taking this medication as general anesthesia can also increase the risk of dangerously low blood pressure if you’re taking losartan (Bertrand, 2001).
- American Heart Association (AHA). (2016, October 31). Low Blood Pressure – When Blood Pressure Is Too Low. Retrieved Sep. 8, 2020 from https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/low-blood-pressure-when-blood-pressure-is-too-low
- Bertrand, M., Godet, G., Meersschaert, K., Brun, L., Salcedo, E., & Coriat, P. (2001). Should the Angiotensin II Antagonists be Discontinued Before Surgery? Anesthesia and Analgesia, 92(1), 26-30. doi:10.1097/00000539-200101000-00006. Retrieved from https://pubmed.ncbi.nlm.nih.gov/11133595/
- Burnier, M. (2001). Angiotensin II Type 1 Receptor Blockers. Circulation, 103(6), 904-912. doi:10.1161/01.cir.103.6.904. Retrieved from https://www.ahajournals.org/doi/10.1161/01.cir.103.6.904
- DailyMed. (2020). Losartan Potassium tablets 25 mg, film coated. Retrieved on Sep. 2, 2020 from https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a3f034a4-c65b-4f53-9f2e-fef80c260b84
- Food and Drug Administration (FDA). (2018, October). Cozaar (losartan potassium) label. Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/020386s062lbl.pdf
- Han, H. (2013). Blood pressure medications: ACE-I/ARB and chronic kidney disease. Journal of Renal Nutrition, 23, e105–e107. Retrieved from https://www.jrnjournal.org/article/S1051-2276%2813%2900152-0/pdf
- Malta, D., Arcand, J., Ravindran, A., Floras, V., Allard, J. P., & Newton, G. E. (2016). Adequate intake of potassium does not cause hyperkalemia in hypertensive individuals taking medications that antagonize the renin angiotensin aldosterone system. The American Journal of Clinical Nutrition, 104(4), 990-994. doi:10.3945/ajcn.115.129635. Retrieved from https://academic.oup.com/ajcn/article/104/4/990/4557116
- National Institutes of Health (NIH). (2019, June 05). Harmful Interactions. Retrieved Sep. 8, 2020 from https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/harmful-interactions-mixing-alcohol-with-medicines
- National Kidney Foundation. (2020, August 26). What is Hyperkalemia? Retrieved Sep. 2, 2020 from https://www.kidney.org/atoz/content/what-hyperkalemia
- Palmer, B. F. (2004). Managing Hyperkalemia Caused by Inhibitors of the Renin–Angiotensin–Aldosterone System. New England Journal of Medicine, 351(6), 585-592. doi:10.1056/nejmra035279. Retrieved from https://www.nejm.org/doi/full/10.1056/nejmra035279
- Palmer, B. F. (2015). Regulation of Potassium Homeostasis. Clinical Journal of the American Society of Nephrology : CJASN, 10(6), 1050–1060. doi:10.2215/CJN.08580813. Retrieved from https://pubmed.ncbi.nlm.nih.gov/24721891/
- Simon, L. V., Hashmi, M. F., & Farrell, M. W. (2020). Hyperkalemia. Treasure Island, FL: StatPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK470284/
- Tsunoda, K., Abe, K., Hagino, T., Omata, K., Misawa, S., Imai, Y., & Yoshinaga, K. (1993). Hypotensive Effect of Losartan, a Nonpeptide Angiotensin II Receptor Antagonist, in Essential Hypertension. American Journal of Hypertension, 6(1), 28-32. doi:10.1093/ajh/6.1.28. Retrieved from https://academic.oup.com/ajh/article-abstract/6/1/28/148869
- U.S. National Library of Medicine. (2018, February 15). Losartan: MedlinePlus Drug Information. Retrieved Sep. 8, 2020, from https://medlineplus.gov/druginfo/meds/a695008.html
Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.