Losartan plus hydrochlorothiazide

Losartan plus hydrochlorothiazide is used to treat high blood pressure. Find out how to take it safely and possible side effects.

What is losartan plus hydrochlorothiazide?

Losartan plus hydrochlorothiazide is used to treat high blood pressure (hypertension). It consists of 2 medicines in a single tablet, which work together to control your blood pressure. Losartan works by relaxing your blood vessels and hydrochlorothiazide helps your body get rid of extra salt (sodium) and water. 


In Aotearoa New Zealand the strength of the losartan plus hydrochlorothiazide tablet is losartan 50 mg + hydrochlorothiazide 12.5 mg. 

  • The usual dose is 1 tablet once a day. 
  • Depending on your condition, your dose may be increased to 2 tablets once a day.
  • Always take your medicine exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it and any special instructions.

How to take losartan plus hydrochlorothiazide

  • Take your dose once a day, in the morning. You can take it with or without food.
  • Stay hydrated and make sure you drink enough water. This is especially important during exercise and hot weather, which can increase your risk of dehydration. If you do not drink enough water you may feel faint, light-headed or sick. 
  • Limit alcohol while taking losartan plus hydrochlorothiazide. Having the occasional drink while you are taking losartan plus hydrochlorothiazide is safe. However, regularly drinking excessive amounts increase your chance of side effects and reduce the effects of losartan.
  • Missed dose: If you forget to take your dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

Cautions while you are taking losartan plus hydrochlorothiazide

Be careful when taking pain relief medicines

Don't take anti-inflammatory pain relief medication such as ibuprofen, while you are taking losartan plus hydrochlorothiazide. This combination can be very harmful to your kidneys and can cause acute kidney injury. You have a higher risk of harm to your kidneys if you are an older person or are dehydrated. Ask your doctor or pharmacist for a safer pain relief options. Read more about NSAIDs and protecting your kidneys.

Examples of NSAIDs
  • ibuprofen (Ibugesic, I-Profen, Nurofen)
  • diclofenac (Voltaren)
  • naproxen (Noflam, Naprosyn)
  • mefenamic acid (Ponstan)
  • celecoxib (Celebrex)

Have a sick day plan

If you have diarrhoea or vomiting from a stomach bug, or have dehydration from other causes, it’s important to let your doctor know. They may advise you to stop taking losartan plus hydrochlorothiazide for a few days and restart it when you feel better. The reason for this is that this medicine can increase the amount of potassium salts in your blood, particularly if you are dehydrated.

Pregnant or planning a pregnancy

Do not take losartan plus hydrochlorothiazide if you are pregnant, or if there is a chance you could become pregnant. Losartan can cause birth defects and is harmful to unborn babies. Talk to your healthcare provider about alternative blood pressure medicines.

Possible side effects of losartan plus hydrochlorothiazide

Like all medicines, losartan and hydrochlorothiazide can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Dizziness
  • Feeling lightheaded
  • Feeling faint when you stand up
  • This is quite common when you first start this medicine and usually goes away with time.
  • Be careful when getting up from either lying down or sitting to avoid falls. These effects put you at risk of falls and injuries, especially if you are older.
  • Stand up slowly. If you do feel dizzy, sit-down or lie down for a few moments.
  • Avoid alcohol.
  • Tell your doctor if this continues.
  • Headache
  • This is quite common when you first start this medicine and usually goes away with time. Tell your doctor if this continues.
  • Muscle cramps
  • Muscle weakness
  • This is less common and may be a sign of rising potassium levels.
  • Tell your doctor – you may need a blood test to check the amount of potassium in your blood. 
  • Signs of an allergic reaction such as skin rash, itching, swelling of the lips, face, and mouth or difficulty breathing such as chest tightness, or wheezing
  • Allergic reactions are rare but serious.
  • Tell your doctor immediately or ring Healthline 0800 611 116.
  • Signs of problems with your liver such as yellowing of the skin or eyes, dark urine, pain in the abdomen
  • Liver problems are rare but serious.
  • Tell your doctor immediately or ring Healthline 0800 611 116.
For more information on side effects, see the Medsafe consumer information leaflet below.

Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product.

Learn more

The following links have more information on losartan and hydrochlorothiazide:

Losartan and hydrochlorothiazide NZ Formulary Patient Information, NZ


  1. Losartan + hydrochlorothiazide NZ Formulary, NZ
Credits: Health Navigator Pharmacists. Reviewed By: Maya Patel, MPharm PGDipClinPharm, Auckland Last reviewed: 04 Apr 2022