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Losartan side effects

by egpat         23 May 2024

The suffix -sartan indicates that losartan is an angiotensin II receptor blocker, commonly known as ARB. This losartan can be given in the form of potassium, and it is available under the brand name COZAAR. Just like the other ARB's, losartan can be used in the treatment of hypertension both in adults and in children. However, it can be used only for children with an age greater than 6 years.

Since this drug reduces blood pressure as well as inhibits the renin-angiotensin system, it can reduce the risk of stroke in patients with left ventricular hypertrophy. Apart from these two indications, losartan potassium can also be used in the treatment of diabetic nephropathy in patients with type 2 diabetes mellitus. In such people, losartan potassium can be used to reduce the raised serum creatinine levels as well as proteinuria, the excretion of protein in the urine.

1. Dizziness

Losartan can produce some lightheadedness in patients, which may impair their daytime activities. This drug can also produce a few of the central side effects, such as headaches, because of cranial vasodilation. Somnolence and sleepiness are also observed. Vestibular disorders, such as vertigo—a reeling sensation—as well as tinnitus—some noise in the ears—are also possible.

2. Hypotension

Since losartan acts as an anti-hypertensive, it can reduce blood pressure. However, hypotension as a side effect is not commonly observed. A few conditions may increase the hypotensive effects of losartan. For instance, the use of diuretics may increase the hypotensive effect. Thiazide diuretics like hydrochlorothiazide and thiazide-like diuretics such as chlorthalidone can be combined with other anti-hypertensive agents in order to reduce blood pressure and reduce cardiovascular complications.

These drugs mainly act by increasing renal excretion so that the body volume is reduced, thereby reducing the cardiac workload. These diuretics mainly increase the excretion of water, resulting in volume depletion. They can also increase the excretion of sodium, resulting in salt depletion. In patients with volume depletion and salt depletion, these diuretics may produce significant hypotensive effects.

High-capacity diuretics like furosemide can also be used for a few cardiovascular complications. If these diuretics are combined with losartan, then they can produce a significant hypotensive effect. This may result in orthostatic hypotension, so care should be taken when driving vehicles or working with machinery because of any sudden drop in blood pressure when losartan is combined with diuretics.

3. Upper respiratory infections

The use of losartan may induce upper respiratory tract infections. It can cause cold-like symptoms, resulting in nasal congestion and a runny nose. A sore throat can also be observed. Inflammatory conditions like sinusitis and pharyngitis can also be observed.

4. Muscle cramps

Losartan can also produce some back pain, which is one of the important side effects that can be observed in most patients. It can also produce some joint pain, resulting in arthralgia. These are again commonly observed side effects of losartan.

5. Cough

ACE inhibitors are one category of drugs that are again acting on the renin-angiotensin system. These drugs can be identified with the simple suffix "pril." Many drugs like lisonopril, enalapril, ramipril, and fosinopril are ACE inhibitors, and they are used in the management of hypertension. They also inhibit the renin-angiotensin system, but when they are used for longer days, they can produce a dry cough in patients. So ARBs can be used as alternatives for ACE inhibitors.

Therefore, losartan can act as an alternative to ACE inhibitors. However, in people who have previously used ACE inhibitors and shifted to losartan, this drug can also induce dry cough. Even though it produces a less significant dry cough compared with ACE inhibitors, there is still a chance to develop a dry cough in those people who have already taken ACE inhibitors.

6. Hyperkalemia

Losartan increases potassium levels in the serum, resulting in hyperkalemia. This hyperkalemia is more pronounced by many of the factors and other drugs. In mild hyperkalemia, serum potassium levels are variable, ranging from 5.5 to 6.0 millimoles per liter. In moderate hyperkalemia, the serum potassium levels are variable, ranging from 6 to 6.9 millimoles per liter, and in severe hyperkalemia, the serum potassium levels are greater than 7 millimoles per liter.

Now, losartan can produce mild to moderate hyperkalemia in a few of the patients with any risk factors. The induction of hyperkalemia can be identified with a few of the symptoms in people. Losartan may induce confusion, muscle cramps, an altered mental state, and difficulty breathing. The induction of hyperkalemia by losartan is more pronounced with the existence of a few of the factors. For instance, the risk of hyperkalemia increases with the progression of age, the presence of diabetes in the patient, or the existence of renal failure or heart failure.

Apart from these conditions, a few of the drugs can also influence hyperkalemia. Aliskerin is one of the renin inhibitors, which again inhibits the renin angiotensin system. So if this drug is combined with losartan, it can produce severe hyperkalemia. Similarly, a few of the drugs, like beta blockers such as propranolol, can also increase the potassium levels, resulting in hyperkalemia.

Immunosuppressants that are used for organ transplantation, such as cyclosporine and tacrolimus, can also increase the risk. Potassium-spraring diuretics like amiloride, triamterene, and spironolactone and cardiotonics like digoxin and potassium supplements, when combined with losartan, can increase the risk of hyperkalemia. Not only these drugs, but sometimes the diet can also increase the risk.

Intake of potassium-rich foods such as turnips, potatoes, dried peas, avocado, a high intake of bananas, and various types of nuts that are rich in potassium can increase the risk of hyperkalemia when they are combined with losartan.

7. Impaired renal function

Even though losartan is used for the treatment of diabetic nephropathy, it may produce some renal impairment, resulting in oliguria and decreased urinary volume. It can also induce azotemia, resulting in increased nitrogen content within the blood due to the decreased excretion of nitrogenic substances. These conditions may further impair renal functionality, ultimately leading to acute renal failure.

Even ARBs can produce renal artery stenosis, the narrowing of blood vessels supplying the renal system, which may further reduce renal functionality. So in those patients with any pre-existing impairment in renal function, losartan should be carefully given.

8. Fetal toxicity

All the ARBs are teratogenic, including losartan. When this drug is given to pregnant women, it can produce some teratogenic effects, leading to fetal toxicity. That's why this drug is strictly contraindicated for pregnant women. Generally, losartan is not preferred again in breastfeeding women in order to avoid any effects on infants, particularly on the renal system.


Losartan mainly produces dizziness as an important side effect, which results in lightheadedness and sleepiness in people. It can also produce some vestibular disorders, resulting in vertigo and tinnitus. Muscle cramps can be produced, resulting in muscle pain and joint pain. Back pain is another important side effect produced by losartan.

Losartan can produce hypotension when it is combined with diuretics, which produce volume depletion as well as salt depletion. It can increase the cough produced in those patients who have already taken ACE inhibitors. Losartan may increase the serum potassium levels, resulting in hyperkalemia, which is more pronounced with other factors like the existence of diabetes, kidney failure, and heart failure, or by the use of drugs that increase the serum potassium levels, such as renin inhibitors, beta blockers, immunosuppressants, and even potassium-sparing diuretics and potassium supplements.