Losartan Side Effects, Uses – What You Need to Know

Written by Phil Rossi, Antoinette Hatton PharmD

NowRx Pharmacy

Losartan Dosage, Side Effects, & Interactions

Losartan is one of the most frequently prescribed medications in the United States with over 51 million prescriptions written each year. Sold under the brand name Cozaar, it is commonly used to treat high blood pressure in adults. The medication comes in strengths of 25mg, 50mg, and 100mg, usually as a tablet.

Let’s take a look at some frequently asked questions and what you need to know if you’re taking this common medication.

What Is Losartan

Losartan is a prescription medication that belongs to a class of medications called angiotensin receptor blockers or ARBs. It helps reduce blood pressure in adults by blocking the effects of Angiotensin II – a chemical in our body that narrows the blood vessels and raises blood pressure. While losartan is the generic name, the most common brand name for the medication is Cozaar. Both brand name and generic are used to treat high blood pressure in addition to several other less common conditions.

What Is Losartan Used For

Generally, Losartan is used for treating high blood pressure (hypertension). However, it may also be used for several less common conditions including:

  • Lowering the chance of stroke in patients with left ventricular hypertrophy (LVH)
  • To slow the worsening of diabetic kidney disease in patients with Type 2 diabetes who have or had high blood pressure

It is not used with women who are pregnant as it can cause harm or death to the unborn baby.

Is Losartan a Beta Blocker or ACE Inhibitor

Losartan is not a beta blocker or an ACE inhibitor. Instead, it belongs to a class of medications called ARBs or angiotensin receptor blockers. ARBs work by blocking the AT1 receptors found on various tissues throughout the heart, blood vessels, and kidneys. As a result of this, ARBs are able to reduce the effects of angiotensin II which include narrowing of the blood vessels (vasoconstriction).

Similarly, angiotensin-converting enzyme (ACE) Inhibitors reduce the effect of angiotensin but through a slightly different mechanism. While ARBs block the receptors that angiotensin II binds to, ACE inhibitors prevent the conversion of angiotensin I into angiotensin II, reducing the amount available for binding.

Generally, a patient will not be prescribed ARBs and ACE inhibitors at the same time. However, always talk with your doctor before you start, stop, or make any change to a medication regimen.

Losartan Dosage

Losartan dosage comes in 25mg, 50mg, and 100mg strength. Your dosage will vary depending on age, current health condition, as well as the purpose of the medication. However, most doctors will prescribe the lowest amount they believe will be effective for the patient.

What is the lowest dose of losartan?  

The lowest dose of losartan is 25mg. People typically start on this dose because it can be effective for some and help their bodies acclimate to the medication. A prescriber may increase the dose if a person’s blood pressure remains high after being on 25mg for a period of time.

The exact time frame for increasing dosage will depend on the patient’s health and circumstances, such as when their follow-up appointment is, how high their blood pressure is at that time, if they see any improvements, etc. Another factor that can affect whether a doctor increases the dose of losartan is kidney function.

What is a good losartan dosage for seniors? 

Losartan is one of the first options for the treatment of high blood pressure in the elderly since it is one of the safest options. Generally, seniors tolerate it well and experience minimal side effects. Seniors also typically start with a dose of 25mg or 50mg. The prescriber may adjust this dose as necessary to achieve results and minimize side effects. 

How Long Does It Take Losartan To Work

Losartan will begin working in the body within an hour of taking it, however, it takes up to 6 weeks to reach maximum efficacy. During this time your body will be adjusting to the medication so it is important to contact your doctor if you experience any side effects.

Most people will not feel a difference as the medication begins to work. They usually feel the same and only notice a difference in their actual blood pressure measurements. The best way to gauge if the medication is working is by tracking your blood pressure over time.  

How Long Does Losartan Stay In Your System

Losartan stays in your system for about 24 hours with 100mg tablets, while lower strengths don’t last as long. As is the case for all oral medications, we say “about 24 hrs” because everyone’s metabolism is different. Liver damage will also impact how long it stays in your system since it is metabolized by the liver. For example, if a patient has end-stage renal disease or congestive heart failure, the body will eliminate losartan faster. 

Losartan Side Effects

Overall, losartan is a pretty well-tolerated medication with minimal side effects. The most common losartan side effects in individuals with high blood pressure include:

  • upper respiratory infection
  • dizziness
  • stuffy nose
  • back pain

These side effects are generally mild and go away with time. If you are experiencing side effects that won’t go away or cause concern you should talk with your doctor.

Additionally, potentially serious side effects of losartan may include:

  • Allergic Reaction
  • Hypotension
  • Swelling in your feet, ankles, hands, or unexplained weight gain
  • High blood levels of potassium

If you are experiencing any of these side effects, call your doctor right away. If you believe you are experiencing a medical emergency, dial 9-1-1 for immediate attention.

What are the long-term side effects of losartan?

Long-term side effects of losartan are rare. However, high potassium levels may cause fainting, irregular heartbeat, and muscle weakness. In addition, kidney damage may occur in patients that have kidney issues. Furthermore, losartan can cause harm or death to an unborn baby so it should not be taken while pregnant.

Does losartan cause weight gain? 

Losartan does not generally cause weight gain. Unexplained weight gain may indicate a worsening in how well your kidneys work, especially if you have existing kidney problems. If you experience unexplained weight gain while taking losartan you should talk with your doctor right away. Do not start, stop, or make any change to your medication regimen without first consulting your doctor.

Does losartan cause ED? 

Losartan may cause ED in some men as hypotension (low blood pressure) makes it difficult for some men to achieve and maintain erections. If you are experiencing ED while taking losartan, you should talk with your doctor right away. Do not start, stop, or make any change to your medication regimen without first consulting your doctor.

Does losartan cause coughing? 

In some cases, losartan may cause coughing and upper respiratory infection. However, these are generally mild and go away over time. Talk with your doctor if your cough persists or becomes intolerable. Do not start, stop, or make any change to your medication regimen without first consulting your doctor.

Losartan Interactions

Losartan may interact with certain prescription and over the counter medication as well as some supplements. It is important you tell your doctor if you are taking any of the following:

  • Potassium supplements
  • Medicine that may increase potassium levels
  • Diuretics
  • Lithium
  • NSAIDs including COX-2 inhibitors
  • Other medicines used to reduce blood pressure

Additionally, you should not take losartan if you are taking the medication Aliskiren or have a known allergy to any ingredient. You should always tell your doctor about all the medicines you take both regularly or otherwise including prescription medication, non-prescription medication, vitamins, and other dietary supplements.

Talk with your doctor or pharmacist if you have questions and do not start, stop, or make any changes to your medication regimen without first consulting your doctor.

What Can I Take Instead of Losartan

Your doctor is the best resource to determine what you can take instead of losartan. Common alternatives include diuretics, with the most common being a thiazide diuretic such as hydrochlorothiazide. Other options may include alternative blood pressure medications like ACE inhibitors, beta-blockers, or calcium channel blockers.

If you have questions, talk with your doctor or pharmacist to determine the best option for your individual needs.

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