Common questions about losartan

Losartan is a type of blood pressure-lowering medicine called an angiotensin receptor blocker.

Like other angiotensin receptor blockers, losartan relaxes and widens your blood vessels. This lowers your blood pressure and makes it easier for your heart to pump blood around your body.

In diabetic kidney disease, it helps to protect your kidneys and slows down the disease. It does this by reducing the amount of protein you lose through your kidneys and by reducing high blood pressure.

Losartan starts to reduce high blood pressure after about 1 hour but it may take 3 to 6 weeks to fully take effect.

If you have high blood pressure, you may not have any symptoms. In this case, you may not feel any different when you take losartan. This does not mean that the medicine is not working. It's important to keep taking it.

Losartan is generally safe to take for a long time. In fact, it works best when you take it for a long time.

However taking losartan for a long time can sometimes cause your kidneys not to work as well as they should. Your doctor will check how well your kidneys are working with regular blood tests.

Candesartan, irbesartan and valsartan are other angiotensin receptor blockers that work in the same way as losartan.

Other types of blood pressure-lowering medicines include:

• calcium channel blockers like amlodipine
• angiotensin converting enzyme (ACE) inhibitors like ramipril
• beta blockers like bisoprolol
• tablets which make you pee more (diuretics) like bendroflumethiazide

The medicine your doctor prescribes will depend on your age and ethnicity:

• if you're under 55 and not of African Caribbean or Black African origin, you'll usually be offered an ACE inhibitor or an angiotensin receptor blocker
• if you're 55 or older, or you're any age and of African Caribbean or Black African origin, you'll usually be offered a calcium channel blocker

Many people need to take a combination of different medicines to lower their blood pressure.

Losartan works as well as other angiotensin receptor blockers when it's used to lower blood pressure. Its side effects are also similar.

It also works as well as ramipril and other angiotensin converting enzyme (ACE) inhibitors to lower blood pressure.

Losartan can be taken by people who have tried ramipril or other ACE inhibitors but had to stop taking them because of side effects such as a dry, irritating cough.

Even if your blood pressure is successfully lowered by losartan, it's best to carry on taking it. If you stop taking losartan, your blood pressure could go up again.

If you need medicines to lower your blood pressure, you'll probably need to take them for the rest of your life.

Remember, by keeping your blood pressure low, you're protecting yourself against having a heart attack or stroke in the future.

If you need a general anaesthetic for an operation, tell your doctor that you're taking losartan. This is because losartan can reduce your blood pressure when it's used with general anaesthetics.

Your doctor will probably advise you to stop taking losartan 24 hours before surgery.

Medicines like nifedipine are used first for Raynaud's phenomenon. But if your condition does not improve, your doctor might try a different medicine.

There have been some studies which have looked at whether blood pressure medicines could help protect people against Alzheimer's disease. However, at the moment, there is not enough evidence to recommend taking losartan or other similar medicines for Alzheimer's.

There are steps you can take that may reduce your risk of Alzheimer's. If you are worried about getting Alzheimer's disease in the future or have a family history of this condition, speak to your doctor.

Losartan will not affect any type of contraception.

However, some types of hormonal methods of contraception, such as the combined pill and contraceptive patch, are not usually recommended if you have high blood pressure. Talk to your doctor if you're taking or using a combined hormonal contraceptive.

If you are taking losartan and it makes you sick (vomit), or have severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Check the pill packet to find out what to do.

Find out more:

• What to do if you're sick or have diarrhoea when taking the combined pill
• What to do if you're sick or have diarrhoea when taking the progestogen-only pill

Losartan can make you feel dizzy, especially when you first start taking it or after taking a bigger dose. If this happens to you, do not drive a car, ride a bike, or use tools or machinery until you feel better.

It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.

Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking losartan. GOV.UK has more information on the law on drugs and driving.

Drinking alcohol can increase the blood pressure-lowering effect of losartan, which can make you feel dizzy or light-headed.

During the first few days of taking losartan or after a dose increase, it's best to stop drinking alcohol until you see how the medicine affects you.

If you find losartan makes you feel dizzy it's best to stop drinking alcohol.

Do not use salt substitutes such as Lo-Salt. This is because they are high in potassium. When mixed with losartan they may make the level of potassium in your blood too high.

Do not drink grapefruit juice if you're taking losartan. It may affect the levels of losartan in your blood and this may change how well it works and whether you have side effects.

Apart from this and not drinking alcohol if you have side effects, there's nothing else you need to avoid while taking losartan. Eating a healthy, balanced diet can help if you have high blood pressure.

You can boost the health of your heart by making some key lifestyle changes. These will also help if you have high blood pressure or heart failure.

• Quit smoking – smoking increases your heart rate and blood pressure. When you stop smoking, your blood pressure and heart failure symptoms are reduced. Try to avoid secondhand smoke too.
• Cut down on alcohol – drinking too much alcohol raises blood pressure over time. It makes heart failure worse too. Try to keep to the recommended guidelines of no more than 14 units of alcohol a week.
• Exercise – regular exercise lowers blood pressure by keeping your heart and blood vessels in good condition. It does not need to be too energetic, walking every day will help.
• Eat well – aim to eat a diet that includes plenty of fruit and vegetables, wholegrains, fat-free or low-fat dairy products and lean proteins. It's a good idea to follow these tips for a lower salt diet too. Eating too much salt is the biggest cause of high blood pressure. The more salt you eat, the higher your blood pressure will be. Aim for no more than 6g of salt a day, but do not use salt substitutes such as Lo-Salt. These can raise the amount of potassium in your blood.
• Deal with stress – when you're anxious or upset, your heart beats faster, you breathe more heavily and your blood pressure often goes up. This can also make heart failure worse. Find ways to reduce stress in your life. To give your heart a rest, try napping or putting your feet up when possible. Spend time with friends and family to be social and help reduce stress.
• Vaccinations – if you have heart failure, it's recommended that you have the flu vaccine every year and the pneumococcal vaccine as recommended by your GP. Ask your doctor about these vaccinations. You can have them free on the NHS. Coronavirus (COVID-19) vaccination is recommended for most people. Make sure you've had all the doses that you are eligible for. Talk to your doctor if you think you might be in one of the at risk groups.