Pinworm: 100 mg once, repeat in 14 days; many other worms need 100 mg twice daily for 3 days or a single 500 mg chewable.
Mebendazole is an anthelmintic used for several intestinal worm infections. Dose and schedule change by worm type, product strength, and local guidance. The sections below walk you through standard dosing, when to repeat a dose, who should avoid it, and practical tips that help treatment work the first time.
How Much Mebendazole To Take: Dose Guide By Condition
The table shows common patterns seen in clinical guidance and product labels. Local advice may differ. If you are dosing a young child, are pregnant, nursing, on other medicines, or live where specific public-health programs run, talk to your doctor or pharmacist before starting.
| Infection | Usual Dose | Notes |
|---|---|---|
| Pinworm (Enterobius) | 100 mg once; repeat in 14 days | Treat close contacts when advised; strict hygiene for 2–3 weeks |
| Roundworm (Ascaris) | 100 mg twice daily for 3 days | Single 500 mg chewable is used in some programs |
| Whipworm (Trichuris) | 100 mg twice daily for 3 days | Re-check or repeat if symptoms persist after 3 weeks |
| Hookworm (Ancylostoma/Necator) | 100 mg twice daily for 3 days | Alternate regimens exist in some regions |
| Mixed Soil-Transmitted Helminths | 100 mg twice daily for 3 days | Helps cover Ascaris/Trichuris/Hookworm together |
| Preventive Deworming Campaigns | Single 500 mg chewable (program-directed) | Given to eligible age groups in selected areas |
What Mebendazole Treats—and What It Doesn’t
This medicine targets several gut-dwelling worms: pinworm, roundworm, whipworm, and hookworm. It is not the choice for every parasite. Some infections need a different drug class, a longer course, or a specialist plan. If symptoms are severe, if there is blood in stool, fever, weight loss, or you recently traveled and feel unwell, seek medical care fast.
Choosing The Right Product And Strength
You’ll see two common strengths: 100 mg tablets (often swallowed or chewed) and 500 mg chewables. The 100 mg form is used in daily courses (twice daily for 3 days) for many worms. The 500 mg chewable is used as a one-time dose in some settings, including mass-deworming programs. Brands vary by country. Read the leaflet in your box, since excipients and instructions can change by manufacturer.
How To Take It For Best Results
Chew, Crush, Or Swallow?
Chewable tablets should be chewed before swallowing. Standard tablets can be swallowed with water; if a child cannot swallow tablets, many programs allow crushing a tablet and mixing with a small amount of soft food. Always follow the specific leaflet for your pack.
With Food Or Without?
For the intestinal worms listed in this guide, dosing is commonly not tied to meals, and absorption into blood is low. Some labels allow with or without food. Take the medicine the same way each day during a multi-day course.
If You Miss A Dose
On a multi-day course, take the missed tablet when remembered unless it’s close to the next dose; do not double up. For single-dose schedules, take it when remembered the same day. If you vomit soon after dosing or miss more than one dose, speak to a clinician about repeating treatment.
When To Repeat The Dose
With pinworm, a second dose 2 weeks later is standard because eggs survive on surfaces and can hatch after the first tablet. For 3-day courses used in roundworm, whipworm, or hookworm, many guides advise reassessing after about 3 weeks. If symptoms or stool tests still show infection, another course can be given under care.
Hygiene Steps That Boost Cure Rates
For Households Dealing With Pinworm
- Shower in the morning, change underwear daily, and keep fingernails short.
- Wash hands with soap after toilet use and before meals.
- Hot-wash bed linens, towels, sleepwear, and clean high-touch surfaces.
- Discourage nail-biting and thumb-sucking during the 2–3-week period.
These steps cut down reinfection while the medicine clears living worms.
Safety: Who Should Avoid Or Get Advice First
Safety is excellent for short courses when used as directed, but some groups need tailored care.
| Situation | Action | Notes |
|---|---|---|
| Age under 1 year | See a clinician before any dose | Most labels do not recommend routine use |
| Pregnancy | Talk to a clinician for a case-by-case plan | Many labels advise avoiding, especially early pregnancy |
| Breastfeeding | Ask a pharmacist or doctor | Systemic absorption is low; guidance varies |
| Liver disease | Medical advice before dosing | Report jaundice, dark urine, pale stools promptly |
| Metronidazole use | Avoid using together unless directed | Combination has case reports of serious skin reactions |
| Known allergy to benzimidazoles | Do not take | Seek an alternative agent |
Side Effects You May Notice
Most people feel fine. Short courses are linked with mild stomach pain, diarrhea, gas, or nausea. Headache can occur. Rashes are uncommon. Rare reports include liver-related lab changes, hair loss, low white blood cells, or severe skin reactions. Stop the medicine and get care fast if you see widespread rash, blistering, mouth sores, yellowing eyes, dark urine, pale stools, or unusual bruising.
How Mebendazole Works
Worms need a tubulin-based system to absorb nutrients. This drug disrupts that system and starves them within the gut lumen. Because little of the drug reaches the bloodstream in standard use, side effects outside the gut are limited compared with agents designed for tissue parasites.
Single 500 Mg Chewable Vs 100 Mg Tablets
Both regimens appear across labels and public-health programs. The one-time 500 mg chewable simplifies logistics in group campaigns and may be used for some individual cases. The 100 mg twice-daily plan for 3 days remains common for roundworm, whipworm, and hookworm. For pinworm, a single 100 mg tablet with a second tablet 2 weeks later is the usual path.
When Another Drug May Be Better
If a lab or clinician suspects a worm outside the gut wall, a tapeworm, or strongyloidiasis, a different agent is typically chosen. Albendazole is preferred for several non-luminal helminths; ivermectin is preferred for Strongyloides. If you are not improving, don’t keep repeating the same course on your own—book an appointment and bring details of what you took and when.
Practical Scenarios
Adult With Pinworm In A Shared Apartment
Take one 100 mg tablet now and repeat in 14 days. Ask housemates to follow hygiene steps and to speak with a pharmacist about taking a single tablet on the same schedule. Clean shared bathrooms daily during this period.
Parent Treating A School-Age Child For Whipworm
The go-to plan is 100 mg morning and evening for 3 days. If symptoms or stool tests still point to infection after about 3 weeks, the clinician may repeat the course or switch agents.
Traveler With Roundworm After A Rural Trip
A 3-day course at 100 mg twice daily is typical, paired with hydration and hand hygiene. If there is fever, severe pain, signs of blockage, or weight loss, seek care immediately.
Interactions And Precautions
- Metronidazole: avoid pairing unless a clinician directs it.
- Carbamazepine and phenytoin: can change levels of related benzimidazoles; give your prescriber a full medication list.
- Alcohol: no specific prohibition with mebendazole alone, but skip it if you are also taking metronidazole for any reason.
Proof-Backed Guidance You Can Trust
Public agencies and product labels align on the core schedules in this guide. For pinworm dosing and the two-week repeat, see the CDC clinical overview. For roundworm, whipworm, and hookworm schedules including the option of a single 500 mg chewable in selected settings, see the CDC page on soil-transmitted helminths. In regions that run school-based deworming days, the WHO deworming guidance describes the single-dose strategy used in campaigns.
Simple Checklist Before You Dose
- Confirm the target worm if you can—stool testing helps when symptoms don’t match pinworm.
- Pick the right product strength; read the leaflet in the box.
- Set reminders: morning and evening for 3 days when using 100 mg courses; a calendar alert for the 14-day repeat with pinworm.
- Plan hygiene steps for the household for 2–3 weeks.
- If symptoms persist or worsen, arrange care and bring your dosing timeline.
Bottom Line For Safe, Effective Dosing
Pinworm is usually handled with a single 100 mg tablet and a repeat at day 14, plus strict hygiene. Roundworm, whipworm, and hookworm are commonly treated with 100 mg twice daily for 3 days, or a single 500 mg chewable in settings where that is standard. Stick to the product leaflet and trusted public-health guidance, and loop in a clinician if you’re dosing a baby, are pregnant, nursing, on interacting drugs, or not getting better.