Losartan (often sold under the brand name Cozaar) is a prescription medication used for managing cardiovascular health. Its primary role is treating high blood pressure (hypertension). It is also prescribed to protect the kidneys in patients who have type 2 diabetes and a history of hypertension. Like all medications, Losartan carries a potential for adverse reactions, making it important to understand its side effects.
Losartan’s Role in Managing Hypertension
Losartan is classified as an Angiotensin II Receptor Blocker (ARB), a class of drugs designed to affect the body’s vascular system. The medication works by selectively blocking the action of the potent hormone Angiotensin II. Angiotensin II normally causes blood vessels to constrict and narrow by binding to AT1 receptors. By preventing this binding, Losartan allows the blood vessels to relax and widen (vasodilation), which ultimately lowers overall blood pressure.
The drug is often prescribed to reduce the risk of stroke in people who have high blood pressure and left ventricular hypertrophy (a thickening of the heart muscle). Its ability to lower blood pressure and reduce pressure within the kidneys also provides a protective effect for those with diabetic nephropathy. Losartan has a sustained duration, allowing many patients to take it effectively just once a day.
Common Side Effects, Including Insomnia
Losartan is generally well-tolerated, but it can produce a range of adverse effects that are usually mild and lessen as the body adjusts. Sleep disturbances, including insomnia, have been reported in clinical trials. Although not a frequent reaction, Losartan’s impact on the body can indirectly disrupt sleep cycles.
For instance, the intended effect of lowering blood pressure can sometimes cause hypotension (excessively low blood pressure), leading to headaches or dizziness that interfere with sleep. Losartan can also influence electrolyte balance, potentially causing elevated potassium levels (hyperkalemia). This may trigger muscle cramps or joint pain that disrupt nighttime rest.
Other common side effects include:
- General fatigue.
- Upper respiratory symptoms, such as nasal congestion or signs similar to the common cold.
- Musculoskeletal discomfort, including back or joint pain.
- Dizziness or lightheadedness, particularly when standing up quickly.
Serious Adverse Reactions Requiring Immediate Attention
Although rare, Losartan carries the potential for severe adverse reactions that necessitate immediate medical care. One of the most serious reactions is angioedema, which involves rapid swelling of the deep layers of the skin, often affecting the face, lips, tongue, or throat. Swelling, difficulty swallowing, or trouble breathing must be addressed immediately, as this can quickly lead to airway obstruction.
Losartan can cause severely high levels of potassium in the blood (hyperkalemia). While mild elevations may be asymptomatic, a dangerous buildup can cause muscle weakness, unusual tiredness, and irregular heart rhythms. Regular blood tests are necessary to monitor potassium levels, especially for those with existing kidney issues.
Other serious concerns include the risk of acute kidney problems, sometimes signaled by a decrease in urination frequency or volume. Patients may also experience signs of a severe allergic reaction beyond angioedema, such as a widespread rash, intense itching, or severe dizziness indicating anaphylaxis. Severe hypotension (an excessive drop in blood pressure) can cause lightheadedness or fainting and requires prompt attention, particularly if the patient is taking diuretics.
Managing and Reporting Side Effects to Your Doctor
Patients should never abruptly stop taking Losartan without first consulting their doctor, as stopping abruptly can lead to a dangerous spike in hypertension. If side effects occur, keep a detailed log noting when the symptom appeared, its severity, and duration. This documentation helps the doctor determine if the reaction is temporary or warrants a change in treatment.
For common issues like dizziness, rise slowly from a seated or lying position to allow the body to adjust to the lowered blood pressure. If gastrointestinal symptoms like nausea or diarrhea occur, taking the medication with food may help. If persistent insomnia or any other side effect significantly interferes with daily life, communicate this to your healthcare provider. They may adjust the dosage or explore an alternative medication to maintain blood pressure control while minimizing discomfort.