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Side Effects of Losartan (Cozaar)



Cozaar (Losartan) Side Effects, Uses and Pharmacogenetics




Cozaar, which is also marketed under its generic name “losartan,” is a prescription medication used to treat high blood pressure, also known as an antihypertensive medication. Cozaar is an angiotensin II receptor blocker or ARB, and it may also be used to treat diabetic nephropathy, which is damage that occurs in the kidneys after longstanding or uncontrolled diabetes mellitus. ARBs, including Cozaar, are recommended for people with heart failure, though this is considered an “off-label” use.


Serious Side Effects of Cozaar


While it is very rare, one of the most feared Cozaar adverse effects is angioedema, according to the Cozaar drug label reported by the FDA. Angioedema is a swelling of the tongue, lips, and throat. This swelling can come on rapidly. If severe, the swelling blocks a person’s upper airway, making it difficult or impossible to breath. Angioedema is a medical emergency that requires prompt medical attention.


Hyperkalemia, or an abnormally high level of potassium in the blood, is a potentially life-threatening side effect of losartan. This adverse event is more likely to occur in people with type 2 diabetes, especially those who already have kidney disease. Blood potassium levels and kidney function are monitored during treatment with Cozaar, especially in the first several weeks to months of starting treatment.


Cozaar Black Box Warning


The FDA has issued a “black box” warning for women who take losartan (Cozaar). According to the FDA Drug Safety Guidelines, ARBs and ACE inhibitors can cause serious injury and death to developing fetuses. Therefore, these drugs should not be prescribed to pregnant women. Furthermore, losartan (Cozaar) should be stopped as soon as a woman learns that she has become pregnant. It is not clear if losartan can be passed in the breast milk to nursing babies. Therefore, women who are breastfeeding should not take losartan (Cozaar) or should stop breastfeeding while on the medication.


Common Side Effects


The most common of the Cozaar side effects according to the Cozaar drug label is coughing. Up to 17% of people who take the ARB develop a persistent dry cough. In some, this cough is so troubling that they cannot tolerate the medication. Once the Cozaar is stopped, the cough goes away. Other Cozaar side effects include:

  • Chest pain
  • Fatigue
  • Hypoglycemia (low blood sugar level, occurs in people with type 2 diabetes)
  • Weakness
  • Diarrhea
  • Orthostatic hypotension (low blood pressure and feeling faint upon standing up)
  • Myasthenia gravis (muscle weakness, blurred vision, slurred speech, facial droop)
  • Dizziness
  • Hyperkalemia (high potassium level in the blood)
  • Anemia (low number of red blood cells in the blood)
  • Back pain
  • Upper respiratory tract infection (e.g. sinus infection, sore throat, laryngitis)
  • Nasal congestion (stuffy nose)

Understand Your Risks with the Rxight® Genetic Test


Rxight® genetic testing determines how Cozaar and other ARBs will metabolize in your body. Knowing how you will react before the medication is taken allows you to find the dosing that is right for you so you can avoid these potentially damaging side effects if Cozaar and over 200 other prescription and OTC medications across dozens of significant medication classes. Rxight® is quick, affordable and easy – only a cheek swab of your DNA is required to send to our lab for analysis. Your doctor can use this information to prescribe the right medication for your genome. If the medication is not appropriate for you, the DNA testing result will guide your prescribers in finding a suitable drug for your condition.

Contributors to this Article: Michael Sapko, MD, Phd and Deborah Kallick, PhD, Medicinal Chemistry

Read more about Rxight® pharmacogenetic testing