What is Atovaquone/Proguanil 250/100 mg Medicine?

Atovaquone/Proguanil 250/100 mg is a prescription antimalarial used to help prevent malaria infection in adults travelling to regions where malaria is common.

It combines two active ingredients—atovaquone and proguanil—that work together to block the malaria parasite’s ability to survive in the blood after a mosquito bite.

Atovaquone interferes with the parasite’s energy production, while proguanil stops it from making new DNA.Taken together, these actions prevent malaria parasites from multiplying and causing illness.

It is strongly recommended for travellers visiting areas with chloroquine-resistant Plasmodium falciparum such as parts of sub-Saharan Africa, South America and Asia.

What is Atovaquone/Proguanil 250/100 mg Used For?

Malaria Prevention

Atovaquone/Proguanil 250/100 mg is used to prevent malaria in adults visiting malaria-endemic regions.
It is not intended to treat malaria once infection has occurred.

How Atovaquone/Proguanil 250/100 mg Medication Works

Atovaquone/Proguanil works at several stages of the parasite’s life cycle to prevent illness after a mosquito bite.

Interferes with energy production – Atovaquone blocks the parasite’s mitochondria, starving it of energy.
Prevents DNA replication – Proguanil disrupts DNA synthesis, stopping the parasite from reproducing.
Blocks infection – Together, they prevent parasites from maturing in the bloodstream.

When to Consider Atovaquone/Proguanil 250/100 mg Medication for Malaria

Adults travelling to regions where Plasmodium falciparum malaria is common—such as much of sub-Saharan Africa, parts of South America, and Asia—should consider this medicine for protection.
Begin prophylaxis 1–2 days before entering the area, continue every day during travel, and for 7 days after leaving.

Who Should Take Atovaquone/Proguanil 250/100 mg

This medicine is suitable for adults (18 years and older) who are fit, healthy, and travelling to a malaria-endemic area as advised by a healthcare professional.

Who Should Not Take Atovaquone/Proguanil 250/100 mg

Avoid this medication if you:

Are pregnant (especially first trimester) or breastfeeding, unless a specialist recommends it.
Have severe kidney impairment.
Are allergic to atovaquone, proguanil, or any tablet ingredient.

Always consult a healthcare provider before use.

Can Atovaquone/Proguanil 250/100 mg Medicine Be Purchased Over the Counter?

No. In the UK it is prescription-only.

A prescriber will review your travel plans and medical history before supplying it to ensure correct dosing and safety.

Atovaquone/Proguanil 250/100 mg Alternatives

Other prescription antimalarials include:

Doxycycline – taken daily, start 1–2 days before travel, continue 4 weeks after return.
Mefloquine – weekly dosing, start 2–3 weeks before travel.

Your 123Meds prescriber will advise which is best for your destination.

How to Take Atovaquone/Proguanil 250/100 mg Medication

Dose: One tablet daily with food or a milky drink to improve absorption.

Timing: Start 1–2 days before entering a malaria area, continue daily during travel, and for 7 days after leaving.

Missed dose: Take as soon as remembered unless the next dose is due; never double up.

Active: Atovaquone 250 mg, Proguanil hydrochloride 100 mg

Inactive (may vary by manufacturer): Microcrystalline cellulose, croscarmellose sodium, magnesium stearate, colloidal silica.

Always read the patient information leaflet (PIL) in your pack for the complete list of ingredients, and to check for any you might be allergic to.

Atovaquone/Proguanil 250/100 mg Medication Side Effects

Common side effects include:

Nausea, stomach pain or diarrhoea
Headache or dizziness

If you notice swelling of the face or throat, trouble breathing, high fever, persistent vomiting or diarrhoea that prevents taking tablets, call 999 or go to A&E immediately.

For less urgent concerns (e.g. mild rash, ongoing stomach upset), contact your GP, pharmacist, or NHS 111 for advice.