Meds and you

Updated 11 February 2013


Losartan is often prescribed to relax and widen blood vessels in persons with high blood pressure.


Losartan is the active ingredient of Cozaar.

Losartan is also one of multiple active ingredients found in Cozaar Comp (Losartan + Hydrochlorothiazide) and Fortzaar (Losartan + Hydrochlorothiazide).

General Information

Losartan is often prescribed to relax and widen blood vessels in persons with high blood pressure. As a result blood pressure is lowered and the heart's workload reduced.

It is of particular use in the patients taking drugs such as enalapril, captopril and related products (ACE inhibitors), which cause a dry and irritating cough. While still providing the same benefit, losartan reduces the likelihood of coughing.

Losartan may be used on its own or in combination with other medication for high blood pressure.

The first few doses of this drug may cause dizziness if you get up suddenly from a sitting or lying position. It is advised to get up carefully until you know how this drug affects you.

Losartan should not be used if you are pregnant or planning to become pregnant. Adequate contraception is advised in women of childbearing age.

How does losartan work?

Losartan blocks the effect of Angiotensin II, a naturally occurring substance that narrows blood vessels. As a result blood vessels widen and high blood pressure is reduced.

Fast facts

Drug schedule: Schedule 3

Available as: Losartan is available as tablets.

What does it do? Losartan lowers blood pressure and reduces the workload of the heart.

Overdose risk: Medium

Dependence risk: Low

Is losartan available as a generic? No

Is losartan available on prescription only? Yes

User information

Onset of effect: Maximum effect is reached within 6 weeks.

Duration of action: Up to 24 hours

Dietary advice: This medication can be taken with or without food.

Stopping this medicine: Do not discontinue this drug without speaking to your doctor first. Premature stoppage may allow return or even worsen symptoms.

Prolonged use: No problems are expected with prolonged use. Your doctor may keep an eye on blood potassium levels

Special precautions

Consult your doctor before using this drug if:

  • You have liver or kidney disease
  • You have congestive heart failure
  • You have a narrowing of the arteries of the kidneys
  • You are allergic to ANY medicine
  • You are taking other medication.

Pregnancy: Avoid. Potential risk to the foetus has been reported. Consult your doctor before use, or if you are planning to fall pregnant.

Breastfeeding: Avoid. This medication is passed through breast milk and may affect your baby adversely. Consult your doctor before use.

Porphyria: Avoid. It is unknown how this medication may affect your condition. Consult your doctor before use.

Infants and children: This medication is not intended for use in children.

Elderly: Caution is advised in the elderly, as a reduced dose may be needed in patients over 75.

Driving and hazardous work: Caution is advised, as use of this medication may lead to dizziness, light-headedness and/or sedation. Avoid such activities until you know how this medication affects you.

Alcohol: Avoid concomitant use of alcohol with this medication.

Possible side effects:

Side effect


Consult your doctor



Only if severe

In all cases












Taste disturbance



Skin rash/itch



Cough/difficulty breathing



Tiredness/feeling unwell




Drug interactions:

Anaesthetic drugs

May lower blood pressure further.


May cause potassium toxicity.


May lower blood pressure further.


Increased risk of lithium toxicity.

Non-steroidal anti-inflammatory drugs

May reduce effect of losartan.

Potassium supplements

May cause potassium toxicity.


May reduce effect of losartan.

Overdose action

A small overdose is no cause for concern. In case of intentional large overdose, seek emergency medical attention. Symptoms may include dizziness and fainting.

Recommended dosage

Adults: 50-100 mg once daily


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