Do I chew the 100 mg tablet or swallow it? My kid refuses dry pills.
One 100 mg chewable is the start of pinworm treatment, not the finish
The Emverm 100 mg chewable is a peach, round, unscored tablet. Adults and children 2 years and older take one tablet once for Enterobius vermicularis. That sentence is the entire pinworm row on the US dosing table. It is also the sentence people stop reading.
A single 100 mg dose is aimed at the worms you have now. Pinworm females lay eggs on the skin at night. Those eggs are not a reliable target for the first swallow. Kids scratch, eggs ride under nails, and the next generation hatches on a delay. If you treat the itch and throw the blister pack away, the household often meets the same worm in a fortnight.
CDC's clinical overview is blunt about the repeat. The medicines used for pinworm, including mebendazole 100 mg, kill worms and cannot kill eggs. A second 100 mg is given two weeks later to catch newly hatched adults. That is why this page locks a 2-3 week second dose instead of celebrating a one-tablet cure.
The US tablet label uses a slightly different trigger: if the patient is not cured three weeks after treatment, a second course is advised. Clinics that follow CDC will often just schedule the second 100 mg at two weeks and not wait for a symptom quiz. Both clocks sit in the 2-3 week window. Pick one with the prescriber and write it on the calendar the day you take the first chewable.
Vermox is the older trade name still printed on many non-US leaflets and on older US memories. The current US 100 mg chewable label in DailyMed is Emverm. The INN is mebendazole either way. Do not mix this 100 mg pinworm tablet with overseas 500 mg single-dose chewables used for other worms. Strength first, then the schedule.
Why the two-week repeat exists
Pinworm eggs are the part of the life cycle a 100 mg chewable does not finish. Adult worms in the gut take the hit. Eggs already on perianal skin, pajamas, and bedroom dust do not. Those eggs are small enough to ride a fingernail back to the mouth. The hatch then rebuilds an adult population after the first tablet is gone.
CDC times the second dose at two weeks for that reason. UK threadworm leaflets often say a doctor may ask for a second tablet after two weeks in case of reinfection. US Emverm uses a three-week cure check as the official second-course trigger. If you need one household rule that does not fight those documents, it is 100 mg now and 100 mg again in 2-3 weeks.
Young worms are the stubborn ones in the clinical reviews. That is another way of saying the same egg problem. A tablet that lands while the cohort is still eggs will look like a failure two weeks later even if the first adults died on schedule. The repeat is not an admission that 100 mg is weak. It is an admission that eggs are not worms.
Hygiene has to cover the same two weeks. Morning showers, trimmed nails, washed hands, and hot laundry on underwear and bedding cut the egg load the tablet never sees. CDC notes that control is hard in day care and boarding settings because repeat infection is the norm. Mass treatment of a classroom, repeated in two weeks, is a public-health version of the same clock.
If itching stops on day 2, you still take the second 100 mg. Symptom relief is not a stool certificate. Pinworm diagnosis is often a tape test at night, and families skip the follow-up tape. The calendar dose is cheaper than a second month of scratching. If the cycle keeps returning after two correctly timed 100 mg doses plus laundry, ask about a missed contact, not a stronger fantasy tablet.
What two 100 mg chewables cost at a US counter
100 mg x 2
Pinworm pair: today and the 2-3 week repeat
Publix pharmacy100 mg x 2
Chain cash window for Emverm chewables
Walgreens pharmacy100 mg x 2
Mail list if the chewable is stocked
Cost Plus Drugs pharmacy100 mg x 2
Texas grocery pharmacy window
H-E-B pharmacyEmverm 100 mg chewable, two tablets (first swallow plus the labeled 2-3 week repeat), checked September 2026. Drugs.com price guide lists one 100 mg chewable from $318.46 to $634.44. SingleCare lists about $861.83 cash and $636.29 with a coupon for one chewable blister. US mebendazole is still a high-list brand chewable; pyrantel on the drugstore aisle is the OTC pinworm fork. GoodRx and SingleCare are named here, not used as a row href. Each link is that pharmacy only. Gravix does not dispense. Prescription required. ZIP changes the print.
Pinworm on this page is one 100 mg chewable now and the same 100 mg in two or three weeks. The four store cards therefore ask licensed counters for a two-tablet pair, not a three-day soil-transmitted pack.
US list prices for Emverm are high. The caption cites Drugs.com and SingleCare for one chewable, because that is what those pages publish. Pyrantel on a drugstore shelf is the legal OTC fork if the clinician is treating pinworm and Emverm is not the plan. Links go to the pharmacy, not to a coupon site.
The 3-day morning-and-evening course for the soil-transmitted set
| Infection | Emverm 100 mg schedule (age 2 and older) |
|---|---|
| Pinworm (enterobiasis) | 1 tablet once; plan a 2-3 week repeat (CDC at 2 weeks; label second course if not cured at 3 weeks) |
| Whipworm (trichuriasis) | 1 tablet morning and evening for 3 consecutive days |
| Roundworm (ascariasis) | 1 tablet morning and evening for 3 consecutive days |
| Hookworm (Ancylostoma or Necator) | 1 tablet morning and evening for 3 consecutive days |
Whipworm, roundworm, and hookworm share one Emverm row. One 100 mg tablet in the morning and one in the evening, for 3 consecutive days. Adults and children 2 years and older use that same map. The tablet may be chewed, swallowed, or crushed and mixed with food. Food is allowed. Fasting is not required. Purging is not required.
That is 600 mg over three days if every dose is taken. It is not a single 100 mg worm pill. Miss the evening dose on day 2 and the 68% whipworm mean cure gets worse. Set alarms. If a child spits a crushed tablet, do not double the next dose unless the prescriber says to. Call and reset the day.
US Emverm still says that if the patient is not cured three weeks after treatment, a second course is advised. For these worms that second course is another 3-day twice-daily block, not a lone tablet. Stool checks, not itch scores, decide cure for Ascaris, Trichuris, and hookworm. Egg counts can fall a lot even when a hard cure is missed, which is why the label prints both figures.
Overseas Vermox 500 mg single-dose chewables are a different product and a different labeled age in some countries. MedlinePlus and GoodRx still mention that 500 mg Vermox presentation for roundworm and whipworm. Do not import that schedule onto an Emverm 100 mg blister and call it close enough. If the bottle says 100 mg, use the 100 mg table.
Mixed infections use the 3-day row when whipworm, Ascaris, or hookworm is in the mix. A pinworm-only house can stay on the single tablet plus 2-3 week repeat. If both are present, the 3-day course covers the soil-transmitted worms; ask whether pinworm still needs its own timed repeat. That is a clinic sentence, not a blog stack of extra 100 mg tablets.
Avoid metronidazole; watch blood counts only when the dose leaves the usual map
Stops and common effects from the Emverm file
- Avoid metronidazole with mebendazole: SJS/TEN reports.
- Hypersensitivity to mebendazole or tablet excipients: do not take.
- Higher or longer than labeled courses: monitor blood counts for neutropenia.
- Infants under 1 year: convulsions reported; labeled use starts at 2 years.
- Common trial list: anorexia, abdominal pain, diarrhea, gas, nausea, vomiting, rash.
Do not pair mebendazole with metronidazole. Stevens-Johnson syndrome and toxic epidermal necrolysis have been reported with that combination. The Emverm warning is an avoid, not a "monitor and see." Flagyl for bacterial vaginosis or a dental abscess has to wait or switch if the worm tablet is in play. Tell both prescribers.
The only contraindication on the label is hypersensitivity to the drug or its excipients. That is a short list. The serious skin reaction with metronidazole still sits in warnings because it is a known pair, not because every rash is SJS. A simple hive still needs a call. Blistering, peeling, or mouth sores need emergency care.
Agranulocytosis and neutropenia are tied to higher doses and longer durations than soil-transmitted helminth schedules. If someone is using mebendazole in that high-dose way, monitor blood counts. Fever during a prolonged course is a lab day, not a "push through the deworming." The ordinary 100 mg pinworm chewable is not that regimen.
Post-marketing, with mixed formulations, also lists anaphylaxis, convulsions, dizziness, hepatitis, abnormal liver tests, glomerulonephritis, angioedema, urticaria, and alopecia. Those reports cannot give a clean frequency. They are a reason to stop and call if the picture is more than a day of gas and loose stool.
Overdose, as far as the label writes it, is gastrointestinal: cramps, nausea, vomiting, diarrhea. There is no specific antidote. Accidental extra 100 mg in a toddler is a poison-control call, not an internet wait. Keep the blister above small hands. Emverm's US pack is often a single tablet in a carton, which is easy to lose and easy for a child to find.
What the label's mean cure table actually shows
| Worm | Mean cure | Mean egg reduction |
|---|---|---|
| Pinworm | 95% | Not given |
| Whipworm | 68% | 93% |
| Roundworm | 98% | 99% |
| Hookworm | 96% | 99% |
Emverm prints one efficacy table from "various studies." Mean cure rates: pinworm 95%, whipworm 68%, roundworm 98%, hookworm 96%. Mean egg reduction: whipworm 93%, roundworm 99%, hookworm 99%. Pinworm has no egg-reduction percentage on that row.
Read whipworm last if you like good news, because 68% is the honest weak cell. A family that treats Trichuris with one leftover pinworm tablet will miss. They need the 3-day twice-daily course and a stool, then the three-week "not cured" clause if eggs persist. Egg reduction of 93% can still leave a person infectious or symptomatic.
Roundworm at 98% cure and 99% egg reduction is why clinicians still reach for a benzimidazole when Ascaris is the isolate. Hookworm at 96% and 99% sits in the same useful band. Those means pool old study methods. They are not a promise that your household is in the 98th percentile.
Safety in the same file is a different sample. Adverse-reaction listing drew on 6276 subjects in 39 trials with mixed formulations and durations, not only today's 100 mg chewable. The common gastrointestinal list is anorexia, abdominal pain, diarrhea, flatulence, nausea, and vomiting. Rash is on the skin line. The file does not print a neat percentage next to each of those words.
If you want the class context against ivermectin, use the antiparasitic comparison. Ivermectin's US tablet job is Strongyloides and Onchocerca, not this pinworm 100 mg chewable. Borrowing ivermectin 3 mg for a tape-test child is usually the wrong molecule.
Most of the 100 mg never needs to be a blood level
After an oral dose, most mebendazole stays in the gut and works there. That is the pharmacokinetic point of a poorly absorbed benzimidazole. Following 100 mg twice daily for 3 days, plasma mebendazole stays at or below 0.03 mcg/mL. The primary 2-amine metabolite stays at or below 0.09 mcg/mL.
A high-fat meal raises how much gets into blood. The label still says the amount left in the gastrointestinal tract is not expected to change in a big way. Emverm can be taken with or without food. If a child eats first, you do not cancel the chewable. If a child takes it on an empty stomach, you do not add a milk chaser for "absorption." The worm is in the lumen.
What little is absorbed is 90-95% protein bound. Volume of distribution is 1-2 L/kg. The liver does the metabolic work. Metabolites, hydrolyzed and reduced, run at higher plasma levels than parent drug and have no anthelmintic activity. Impaired hepatic function, impaired metabolism, or impaired biliary elimination can raise mebendazole levels.
Apparent elimination half-life is 3-6 hours in most people. Less than 2% of an oral dose leaves in urine. The rest leaves in feces as unchanged drug or metabolites. Some enterohepatic recirculation is likely. None of that asks you to time the 100 mg to a creatinine value. It asks you to finish the pinworm repeat or the 3-day pair of daily tablets.
High-dose, long-duration use is a different exposure and a different safety file. Neutropenia, agranulocytosis, hepatitis, alopecia, and glomerulonephritis show up when people push mebendazole well past soil-transmitted schedules. The 100 mg pinworm chewable is not that experiment. Do not invent a cancer-dose calendar from a pinworm blister.
Treat the household when the clutch is shared
Pinworm is a bedroom and bathroom infection. Mayo's patient page says all household members may need treatment at the same time because the worm moves person to person so easily. CDC says the same for families and for institutions. The Emverm label does not write "dose every cousin" as a legal line. Clinicians still treat the cluster because one untreated sleeper restocks the eggs.
Same-day first doses beat a relay. If a child takes 100 mg on Monday and a parent waits until the weekend, the Monday eggs have a fresh host. Book the repeat 2-3 weeks later for everyone who took the first tablet. Do not give a third or fourth 100 mg the next day because someone still itched. Itch can lag dead worms.
Under 2 years is not this tablet's labeled population. Emverm is indicated from age 2. Convulsions have been reported with mebendazole in infants younger than 1 year. A toddler in a crib next to an infected preschooler is a pediatric decision, not a leftover half-tablet from a parent. Pyrantel is the other named option on CDC's list and is sold without a prescription in the US. It still needs its own age and pregnancy check.
School exclusion is usually the wrong fight. UK threadworm guidance says children do not need to stay home once treatment and hygiene are underway. The useful work is simultaneous 100 mg doses, a written 2-3 week repeat, and laundry. Naming the worm in a group chat helps more than keeping a child out of class for a week.
If the diagnosis is actually hookworm or Ascaris, the household script changes. Those worms are not a bedtime tape-test problem. They need the 3-day course below, and contacts are managed by stool and travel history, not by default dosing of every roommate. Wrong worm, wrong calendar.
The worm loses glucose uptake after the tubulin hit
Emverm 100 mg at a glance
Mebendazole interferes with cellular tubulin formation in the helminth. The gut lining of the worm degenerates at the ultrastructural level. Glucose uptake falls. Digestion and reproduction stall. The worm stops moving, egg production drops, and the helminth dies. That is the microbiology section in one chain, and it is why a luminal drug can work without a high plasma peak.
Activity on the US label is listed by organism: Enterobius vermicularis, Trichuris trichiura, Ascaris lumbricoides, Ancylostoma duodenale, and Necator americanus. If the isolate is something else, this 100 mg chewable may be the wrong tool. Strongyloides is an ivermectin conversation on this site, not a mebendazole default.
Resistance is written as a potential, not a community rate. The likely mechanism is a beta-tubulin change that lowers binding. Clinical meaning is unknown on the label. If a documented Trichuris infection fails a correctly taken 3-day course, the next step is a stool and a specialist, not a silent fourth box of 100 mg tablets.
Chemistry is small next to ivermectin's macrolide. Formula C16H13N3O3, molecular weight 295.29, less than 0.05% soluble in water. The chewable adds cellulose, corn starch, lactose, sodium starch glycolate, magnesium stearate, stearic acid, sodium lauryl sulfate, saccharin, and FD&C Yellow No. 6. Peach color is dye, not flavor proof that a child will like it.
Initial US approval of mebendazole was 1974. Longevity is not a reason to skip the 2-3 week pinworm repeat. The egg clock is older than the tablet.
Chew, crush, or swallow, then keep the 2-3 week date
Emverm description chemistry. The clinical unit is still the 100 mg chewable.
| Spec | Label value |
|---|---|
| Strength | 100 mg chewable |
| Formula | C16H13N3O3 |
| Molecular weight | 295.29 |
| Water solubility | <0.05% |
| US initial approval | 1974 |
How you get the 100 mg down is written in one line. Chew it. Swallow it. Or crush it and mix it with food. Supervise a child. UK Vermox leaflets tell you to crush for younger children who cannot handle a whole tablet. Do not hide a dry tablet in a spoon of jam and walk away.
Pregnancy is not a casual extra tablet. Published human data have not shown a clear link to major birth defects or miscarriage. The studies still cannot prove absence of risk. First-trimester exposures were thin in some of them. Animal work in rats and mice found embryo loss and malformations at doses near or below human mg/m2 multiples. Untreated helminths in pregnancy also harm mother and fetus, including iron-deficiency anemia and low birth weight. That pair of facts is why the obstetrician owns the yes or no, not a school-nurse rumor.
Lactation data are limited case reports of small amounts in milk. Effects on milk volume are inconsistent. The label does not give a clean "pump and dump" number. The patient leaflet tells people to talk through feeding before they take the chewable. Do that instead of guessing from a comment thread.
A US fill is a prescription 100 mg chewable. Coupon and telehealth pages will show Emverm at pharmacies, including chains people already use. Vermox as a US product is no longer the bottle you should expect. If a site offers mystery "mebendazole 100 mg" without a prescription trail, treat it as a different supply problem. Pyrantel from a drugstore is the legal OTC fork for some pinworm cases.
Write two dates when the first 100 mg goes in: today, and 2-3 weeks later. Treat the people who share the house if the clinician is treating a cluster. Wash the linens. If the isolate is Ascaris, Trichuris, or hookworm, switch your head to morning and evening for 3 days. If the isolate is Strongyloides or Onchocerca, you are on the wrong page: that is ivermectin 3 mg. More pinworm technique sits in the 100 mg taking guide.
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Answered by Dr. Elena Marchetti, MD · Infectious diseases & clinical pharmacology
Pinworm questions arrive as calendar questions. These answers start from the 100 mg chewable and the 2-3 week repeat, then the 3-day course when the worm is not Enterobius.
The Emverm label allows all three: chew, swallow whole, or crush and mix with food. For a child who gags on dry tablets, crush it. Stay in the room until it is gone. A tablet left in a spoon of yogurt is how doses disappear. Food is allowed; you do not need to fast or use a purge. The US chewable is 100 mg, peach, unscored, marked ap over 107 on one side. If your bottle is a 500 mg overseas Vermox, stop and re-read the label, because that is a different schedule. Age 2 and older is the Emverm line. Under 2 years, this is not a leftover-crush project. Convulsions have been reported in infants younger than 1 year. If pinworm is the diagnosis, I also want the second 100 mg on the calendar in 2-3 weeks, not only a successful first swallow. The how-to page is how to take mebendazole 100 mg. If the child vomits within minutes, call the prescriber rather than guessing a replacement dose.
Why does everyone say take mebendazole again in two weeks if the box looks like a one-tablet pack?
Because the first 100 mg is aimed at adult pinworms, and eggs are still in the bed. CDC says the usual pinworm drugs do not kill eggs, so a second 100 mg two weeks later kills the worms that hatched in the gap. US Emverm packaging is often a single chewable in a blister, which matches the first dose and quietly drops the reminder. I write the repeat the day we take the first tablet. The label's own backup line is a second course if the patient is not cured at three weeks. That is why this site locks 2-3 weeks instead of fighting CDC versus DailyMed. Buy or request enough 100 mg tablets for both dates, and for other household members if we are treating a cluster. Itch fading on day 3 is not a reason to cancel the second swallow. If you only have one tablet in the house, the missing piece is the repeat, not a different brand name. Vermox leaflets outside the US often mention a second tablet after two weeks for the same egg reason.
Should my partner and the baby take 100 mg too? Only our 6-year-old had a positive tape test.
Partners who share a bed are often treated on the same days, because pinworm eggs do not respect a negative tape test on a single morning. Mayo and CDC both talk about treating the household together. I would rather give the 6-year-old and the adults 100 mg now and 100 mg in 2-3 weeks than watch the child rebound from a parent's untreated nails. The baby is the stop. Emverm is labeled from age 2. Mebendazole has post-marketing convulsions under age 1. A clinician has to choose hygiene alone, delay, or a different agent such as pyrantel with its own age limits. Do not split a 100 mg chewable into "a baby sprinkle." Treat linens and morning bathing as part of the baby's plan. If the tape test was wrong and this is not pinworm, stop the cascade. Ascaris or hookworm in a traveler is the 3-day twice-daily map, not a family pinworm party. I keep the worm-by-worm taking notes at mebendazole for worm infections.
I am on metronidazole for a dental infection. Can I still take the pinworm chewable this weekend?
Not together. Emverm says to avoid mebendazole with metronidazole because Stevens-Johnson syndrome and toxic epidermal necrolysis have been reported with the pair. That is an avoid, not a staggered-by-six-hours workaround I would invent for a weekend. Call the dentist or the person who wrote the metronidazole and the person who wrote the mebendazole. One of the two courses has to move. Pinworm is miserable and not usually an emergency overnight. A dental abscess can be. I would rather delay the 100 mg by a few days than stack SJS risk. When the metronidazole is done, take the 100 mg and immediately write the 2-3 week repeat. If the dentist needs a longer anaerobic course, we pick a different pinworm option, often pyrantel, after a quick interaction check. Do not buy a second dewormer online to "keep the weekend plan." The serious skin reaction is the whole point of that warning. If a rash with blistering starts after any overlap that already happened, that is urgent care, not another tablet.
The clinic said 100 mg twice a day for three days. That is not what the pinworm blog said.
Then you are probably not being treated for pinworm alone. Emverm's 3-day morning-and-evening row is whipworm, roundworm, and hookworm. Pinworm is one 100 mg tablet once, plus the 2-3 week repeat. Blogs collapse those rows because both say "mebendazole 100 mg." The infections do not share a calendar. If a stool showed Ascaris or hookworm, take morning and evening for 3 consecutive days, with or without food, chewed or crushed. If you are not cured at three weeks, the label wants another full course, not a random extra tablet. Whipworm is the weak cell in the mean cure table at 68%, so finishing every dose matters. If the clinic truly meant pinworm and wrote BID for 3 days, ask them to confirm the organism. I would rather you make one phone call than take 600 mg for a tape-test worm or take one tablet for Trichuris. Side-by-side with ivermectin's jobs is at antiparasitic comparison. Ivermectin 3 mg is not a substitute for this chewable.
Is mebendazole safe in pregnancy? We found pinworm after the first-trimester scan.
Do not self-start the 100 mg chewable. The Emverm pregnancy section says published human studies have not shown a clear link to major birth defects or miscarriage. It also says those studies cannot prove there is no risk. Some of them had little first-trimester exposure. Rat and mouse studies found embryo loss and malformations at doses near human mg/m2 multiples. Untreated helminths in pregnancy are also bad: iron-deficiency anemia, low birth weight, and worse maternal and neonatal outcomes sit on that list. That is a specialist call, often hygiene plus delayed drug, or pyrantel, or a later-trimester benzimidazole, depending on the worm and the week. Pinworm can sometimes be managed with strict hygiene for weeks if the obstetric team wants to wait. A 3-day hookworm course is a different maternal-anemia conversation. Bring the tape-test or stool result to obstetric care rather than a leftover tablet from a child's school outbreak. Lactation is a separate limited-data discussion if you are already feeding.
We treated everyone and the itching came back a month later. Did the 100 mg fail?
A month later is the classic missed-egg or missed-person pattern, not proof that 95% mean pinworm cure was a lie. Check three things. Did every treated person take the second 100 mg in the 2-3 week window? Did a regular visitor, a second home, or a classroom cluster get left out? Did laundry and nails actually change for those two weeks? If those are clean and a tape test is positive again, we repeat the pair of 100 mg doses and look harder at contacts. If the worm was never proven, we confirm Enterobius before stacking more benzimidazole. Whipworm that was mislabeled as pinworm would have needed the 3-day course and would look like "failure" after one tablet. Night itch can also be eczema or streptococcal skin disease. I do not raise the pinworm dose above 100 mg to chase a feeling. I confirm the organism. Persistent soil-transmitted eggs at three weeks get a second labeled course and a stool, not an internet "high-dose mebendazole" protocol. Those high-dose regimens are where neutropenia enters the file.
Can I buy Vermox 100 mg at Walgreens without a visit, or is this a prescription situation?
In the US, the 100 mg chewable you want is a prescription product, currently labeled Emverm. Coupon pages will price it at chains, including Walgreens, once a prescription exists. Vermox as a US brand is not the bottle I tell people to expect at the counter. Some countries sell mebendazole without the same gate; a US traveler's leftover is still a strength-and-schedule problem. Pyrantel pamoate is the pinworm medicine CDC lists that you can buy without a prescription in the US. It also needs a two-week repeat and household thinking. If someone is offering "mebendazole 100 mg" from an overseas cart with no clinician, that is a supply risk, not a bargain versus Emverm. Ivermectin 3 mg from the same carts is the wrong pinworm drug anyway; that tablet's labeled jobs are Strongyloides and onchocerciasis, on the ivermectin page. Get the organism named, then pick Emverm 100 mg with a written 2-3 week repeat, or pyrantel, or the 3-day mebendazole course if the stool says so.
Treat every answer here as general teaching, not a decision made for the individual who wrote in. What is right for you turns on your history, your bloods and the rest of your medicine list — and that is a conversation for a prescriber who can see all of it at once.