Chloroquine Phosphate – What You Need to Know

If you’ve ever heard the name chloroquine, you probably think of malaria. It’s a long‑standing drug that’s been used for decades to stop the parasite that causes the illness. In the UK, doctors still prescribe chloroquine phosphate for a few specific cases, even though resistance has limited its use in many parts of the world.

How chloroquine phosphate works and when it’s prescribed

Chloroquine phosphate belongs to a class of medicines called antimalarials. It stops the malaria parasite from multiplying once it’s inside red blood cells. Because it’s cheap and easy to take, it used to be the go‑to drug for travelers heading to malaria‑risk zones.

Today, British guidelines reserve it for:

  • Uncomplicated P. vivax or P. ovale infections where resistance is low.
  • Patients who can’t tolerate newer drugs like artemisinin‑based combos.
  • Prophylaxis for short trips to areas with known chloroquine sensitivity.

If you’re unsure whether chloroquine is right for you, a quick chat with your GP or travel clinic will clear things up.

Typical dosage and safety tips

For treatment, adults usually take 600 mg (that's 300 mg base) on day 1, followed by 300 mg on day 2 and day 3. Children get a weight‑based dose, so your pharmacist will calculate the exact amount. When used as a preventive, a common schedule is 300 mg once a week, starting a week before travel and continuing for four weeks after you return.

Take the tablets with a full glass of water, and try to space them a few hours apart from any antacids, because those can reduce absorption. If you miss a dose, take it as soon as you remember unless it’s almost time for the next one – then skip the missed dose and continue as normal.

Always tell your doctor about other meds you’re on. Chloroquine can interact with certain steroids, heart drugs, and some antibiotics. A quick check with a pharmacist can prevent unwanted side effects.

Speaking of side effects, the most common ones are mild stomach upset, itching, and a headache. More serious reactions – like vision changes, ringing in the ears, or a fast heartbeat – are rare but need urgent medical attention.

Because resistance is a growing problem, you’ll often see doctors recommend newer antimalarial options. Our recent guide on "Top Chloroquine Alternatives" walks you through artemisinin combos, atovaquone‑proguanil, and other up‑to‑date choices that work better in resistant regions.

Bottom line: chloroquine phosphate can still be useful, but only when it’s the right fit for your situation. Stick to the prescribed dose, watch for any unusual symptoms, and keep an open line with your healthcare provider.