Pyrantel pamoate: what it treats, how to take it, side effects
Last updated September 3, 2026.
Pyrantel pamoate is the over-the-counter dewormer you can buy without a prescription, sold as a liquid or tablets under names like Reese's Pinworm Medicine. It paralyzes worms so the body passes them, and for pinworm it usually takes just one dose.
What does it treat?
Pinworm first and foremost, the intensely itchy, household-spreading infection common in school-age kids. It also treats roundworm and hookworm. It works only in the gut, where it paralyzes the worms; it does not treat tissue infections, which is a doctor's job with prescription drugs like albendazole.
How do you take it?
A single dose based on weight: 11 mg per kilogram (5 mg per pound) of pyrantel base, up to a maximum of 1,000 mg. The liquid gets shaken well and can be taken with food, milk, or juice. For pinworm, the dose is typically repeated after 2 weeks, because the drug kills worms but not the eggs hatching later. When one household member has pinworm, treating the entire household at the same time is the standard advice. Missed dose logic barely applies to a one-dose medicine; just take it, then calendar the 2-week repeat.
Side effects to know
- Common: abdominal cramps, nausea, vomiting, diarrhea, headache, dizziness, and drowsiness, usually mild and brief.
- Serious: rare, but allergic reactions happen; liver disease is the main caution flag, since the drug is processed there.
Who should not take it?
Check with a doctor first if there is liver disease or anemia, if the patient is under 2 years old (the OTC label starts at age 2), or if you are pregnant or breastfeeding. Worms other than pinworm, or symptoms persisting after treatment, mean a doctor visit rather than repeat OTC dosing. Do not use it for weight loss or "cleanses"; it has no such effect.
When is it an emergency?
Call 911 for facial swelling, trouble breathing, or a severe rash after a dose. Severe abdominal pain with vomiting, or any worms seen outside the gut pattern (like a worm in the eye), needs urgent medical care. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Is pyrantel pamoate really available without a prescription?
Yes. In the US it is the over-the-counter pinworm treatment, sold as a liquid or tablets, and the label includes the weight-based dosing table. Mebendazole and albendazole, its prescription cousins, cover more worm types, but for straightforward pinworm, OTC pyrantel is the standard first step.
Why do I have to take a second dose 2 weeks later?
Because pyrantel kills worms but not their eggs. Eggs deposited before treatment hatch over the following days, and a dose 2 weeks later catches the new generation before it can lay again. Skip the repeat and reinfection is likely, which is why the cycle feels endless without it.
Does the whole family really need to treat?
The OTC label says it plainly: when one household member has pinworms, the entire household should be treated unless a doctor advises otherwise. Family members without symptoms commonly carry the infection and hand it straight back. Treating only the itchy kid is the classic reason it keeps coming back.
How do I know the dose?
It is purely weight-based: 11 mg of pyrantel base per kilogram, or 5 mg per pound, as a single dose, capped at 1,000 mg. The package insert carries a weight table in pounds. If your scale is off or the child is under 2, ask a pharmacist or doctor before dosing.
Can I use it for any kind of worm?
Pinworm, roundworm, and hookworm are its territory. Tapeworm, whipworm, strongyloides, and any tissue-dwelling infection are not; those need prescription drugs and a diagnosis. If symptoms do not resolve after proper treatment, that is exactly the situation to stop self-treating and get tested.
Is it safe in pregnancy?
Pyrantel is poorly absorbed from the gut, which makes it the relatively preferred option when pinworm treatment in pregnancy is necessary, but the call belongs to your doctor, and hygiene measures come first in pregnancy. Call your doctor if you are pregnant and treating.