I still itch two weeks after scabies treatment. Do I swallow another pile tonight?
Micrograms first, then the 3 mg pile
The arithmetic is the whole skill. Ego about 'how many pills my neighbor took' is how people underdose a 95 kg adult.
| Kilograms | Strongyloides pile at ~200 mcg/kg | 3 mg chips |
|---|---|---|
| 15-24 | 3 mg | 1 |
| 25-35 | 6 mg as two chips | 2 |
| 36-50 | 9 mg as three chips | 3 |
| 51-65 | 12 mg as four chips | 4 |
| 66-79 | 15 mg as five chips | 5 |
| 80 and up | 200 mcg/kg | count from the rate |
Write body weight in kilograms. Multiply by 200 if the organism is Strongyloides stercoralis. Divide by 3000 because each chip is 3 mg, which is 3000 mcg. Round to the labeled band, not to a vibe. A 60 kg adult is not a 90 kg adult. The pile changes.
People want a single lucky number. There is not one. There is a rate and a chip. The rate lives on the FDA table. The chip is 3 mg. I have watched residents recite 'two tablets' as if that were a drug. Two tablets is a sentence about a 25-35 kg Strongyloides band. It is not a personality.
Pediatric and small-adult counts still use the same 3 mg unit. Many protocols stop below about 15 kg. That is a clinician call, not a kitchen split of a chip with a butter knife. If the weight is near a band edge, the label already chose the pile. Do not freelance a half-story.
Two label rates live on one blister
| Kilograms | Oncho pile at ~150 mcg/kg | 3 mg chips |
|---|---|---|
| 15-25 | 3 mg | 1 |
| 26-44 | 6 mg as two chips | 2 |
| 45-64 | 9 mg as three chips | 3 |
| 65-84 | 12 mg as four chips | 4 |
| 85 and up | 150 mcg/kg | count from the rate |
Onchocerciasis uses a lower rate: about 150 mcg/kg. The bands shift. A 70 kg person is not automatically 'five chips' just because they memorized the Strongyloides card. Look at the oncho table. Four chips cover 65-84 kg on that card. The blister did not change. The rate did.
Why two rates? Different parasites, different trial tables, different risk of dying larvae in skin and eye. Do not average 200 and 150 into 175 because it feels tidy. Tidy is how people invent a third label. The live label has two.
Mass campaigns often repeat yearly. Individual retreatment can be as short as three months. That calendar is larval suppression, not a cure of the adult worm in the nodule. If you came for a one-and-done fairy tale, you opened the wrong note.
Fasting is how the trial table was built
Empty stomach, water, then wait before food. That is not etiquette. That is how the exposure in the weight bands was measured. A fatty breakfast can push absorption about two and a half times in the old pharmacokinetic work. Fine if a specialist wants that on purpose. Not fine as a forgotten bagel.
I tell people: swallow on waking, chips in a cup, water, then breakfast an hour later. Phone alarm the night before if you are the person who 'always forgets.' Microgram-per-kilogram math goes soft if the gut is full of butter.
Special cases exist - a clinician chasing a stubborn mite burden may use food on purpose. That is a named decision. It is not your roommate's life hack. Default remains the label: fasting water.
Strongyloides wants a stool after the swallow
One 200 mcg/kg pile clears most intestinal infections. Additional chips are not automatic. Follow-up stool is. Light infections hide. One negative smear is a thin goodbye, especially before steroids or chemo. Serology or repeat samples earn their keep.
Autoinfection is why this worm is not pinworm. Larvae can cycle in the same host for decades. Hyperinfection under immunosuppression is the nightmare chapter - high mortality, ICU, a drug you wish you had given earlier. Screen before the first prednisone burst if the biography includes endemic soil.
I do not treat 'just in case' because a friend once had a rash. I treat a named Strongyloides plan. If the biography is thin and the test is negative twice, I file the chip back. Anxiety is not an indication. The trial ledger is why I trust this row when the organism is real.
Oncho repeats because adults stay in nodules
A single 150 mcg/kg swallow slashes microfilariae. Adult Onchocerca volvulus lives in subcutaneous nodules for years. The chip does not execute those adults. Programs therefore come back. Yearly in many campaigns. Twice yearly in some. Individual clinics may retreat at three months.
Think transmission, not a personal cure tattoo. Flies pick up larvae from skin. If the skin stays quiet, the cycle breaks. That is why a 3 mg campaign tablet can change a map and still leave a nodule on a scapula.
Mazzotti - itch, rash, tender nodes, fever - is dying larvae, often within a day or two. Mild is expected in a heavy skin load. Eye pain that scares you is a clinic visit, not a forum thread. Do not call Mazzotti an allergy to the 3 mg chip unless a clinician says it is.
Scabies second date is an egg clock
Off-label in the US, and still the oral tool I reach for when cream logistics fail. 200 mcg/kg, then a second pile about one to two weeks later, because eggs do not care about your first swallow. Treat the household on the same nights. Hot-wash the bedding. One heroic person and six untreated roommates is how mites win.
Itch can last two to four weeks after the mites are dead. That is debris and immune noise. New burrows are a different sentence. I do not automatically pour a third pile because someone is still scratching on day ten. I look at the skin. I ask who else was dosed.
Crusted disease is a ward problem: many dates, oral plus topical, infection control. Do not copy a simple two-date household plan onto a crusted heel. You will bounce. CDC steps at the CDC scabies pages are the dull checklist I actually use.
Horse paste is not a weight-band
Veterinary tubes are labeled for animals that weigh hundreds of kilograms. The syringe notches are not Stromectol bands. COVID-era emergency rooms filled with people who 'eyeballed' a paste and met confusion, vomiting, low blood pressure, seizures. That is overdose, not a bold biohack.
Human count: 3 mg chips, kilograms, a named parasite. Animal count: a different product, a different species, a different legal channel. I do not convert paste into chips on a napkin. I throw the napkin out.
FDA said this in public English - the FDA warning was not subtle. If a relative 'swears by the tube,' they are swearing by a concentration meant for a horse. I will not bless it in a margin. The unused 3 mg blister in the evidence essay exists because a virus never paid. Paste is how people paid anyway.
Loa loa is the hold before any count
Write the map before you write the kilograms. Central and West Africa change the risk.
Heavy Loa loa microfilaremia plus ivermectin can drop a load of dying worms into the brain's neighborhood - encephalopathy, the rare disaster mass programs built RAPLOA and blood screens to avoid. This is not a US-suburb routine. It is a biography question.
Lived or worked in Loa-endemic forest belts? Say so before anyone piles chips for oncho-scale work. A clinician may check the blood load. That is planning, not a ban. Outside that map, I still ask, then I move on. Skipping the ask is how a rare risk becomes a surprise.
The hold is geographic and burden-related. It is not a reason to fear a labeled Strongyloides swallow in Aberdeen after a negative travel history. Context. The Kawana price note is why campaign tablets reached those forests in the first place. Respect the map they entered.
A kitchen-table count still needs a clinician
Checklist I actually mutter: name the organism, write kilograms, pick 200 or 150, pile 3 mg chips off the matching band, fasting water, plan the second date if eggs or adults demand it, ask Loa if the map is hot, expect itch after mites and Mazzotti after heavy oncho.
What I will not mutter: a neighbor's tablet count, a paste notch, a virus headline, a made-up higher-strength tablet. The chip is 3 mg. The rate is on the label. Your clinician owns the swallow. This library page is a teaching margin.
If the arithmetic and the biography disagree, believe the biography and call the person who can examine you. A blotter cannot see your stool, your nodules, or your housemates. Do not treat a count essay as a standing order.
Reader mail
Reader questions on this article
Answered by Dr. Adaeze Nwankwo, MD · Infectious disease & parasitology
Nine readers asked how to pile the chips. I answer with bands and holds. Not with your kilograms.
Usually no. Post-scabies itch is common for two to four weeks while dead-mite debris keeps the skin noisy. Moisturizer and an antihistamine are the boring tools. New tracks or new household cases are the reason to look again - confirm the second date happened, confirm contacts swallowed, wash the bedding hot. Itch without new burrows is not a third-pile order. I want to see the skin or hear a clear household story before anyone counts more 3 mg chips.
I ate eggs before my dose. Do I repeat the whole count tomorrow?
Do not double on your own. Call the prescriber and say what you ate and when. A full fatty breakfast can raise exposure. A dry biscuit is a smaller problem. Repeating a full 200 mcg/kg pile the next morning because you feel guilty is how people stack days the label never wrote. The fasting rule exists because the bands were measured that way. Guilt is not a second band. Let a clinician decide if anything needs repeating.
How many 3 mg chips for 82 kg? The high-weight row just says 200 mcg/kg.
Because the printed Strongyloides table stops giving a chip count at 80 kg and sends you back to the rate. 82 times 200 is 16400 mcg, which is 16.4 mg, which is between five and six 3 mg chips. Your prescriber rounds on the label's logic, not on a forum. I will not remote-dispense a sixth chip from Aberdeen. Write 82 kg on the script so the pharmacy can see the same number you used. If weight changed a lot since last year, recount. Do not reuse an old pile.
Why is oncho 150 and Strongyloides 200 if it is the same 3 mg chip?
Different trial tables, different parasites, different larval-die-off risk in skin and eye. The chip did not change. The rate did. Memorize two cards, not one 'ivermectin dose.' Mixing them is how a 70 kg traveler gets the wrong pile. I keep both tables on the blotter. You should too. If someone quotes a single number for every worm, they are not reading Stromectol. They are reading a meme.
My brother used horse paste and 'felt fine.' Why is your tone so sharp?
Because 'felt fine' is not a therapeutic index. Paste tubes are built for equine kilograms. Human 3 mg chips are built for a labeled band. Poison-control spikes during the virus years were not a myth - confusion, hypotension, seizures. A lucky swallow does not rewrite the product. I am sharp because I have already had that conversation too many times, and one of them ended in an ICU. Fine once is not a protocol. Read why the virus row stayed blank if that is the real argument hiding under the paste.
I lived in Cameroon for three years. What do I actually tell a doctor before a swallow?
Say the country, the years, the kind of work, and whether anyone ever mentioned Loa or eye worm. That biography can trigger a blood look before oncho-scale dosing. It is not a scarlet letter. It is the hold I write first. A labeled Strongyloides course in someone with a light, old history may still proceed after a clinician thinks. Do not hide the map to 'keep it simple.' Simple is how rare encephalopathy stays a surprise. Bring the map. Let them decide the pile.
Can I split a 3 mg chip for a child who is 12 kg?
Not as a home project. Many protocols sit the oral tablet at or above about 15 kg. Below that, the conversation is clinician-only - sometimes a different route, sometimes wait, sometimes a calculated exception I will not invent on a library page. Do not butter-knife a chip and call it pediatrics. For household scabies, the child is rarely the only person who needs a plan. Treat the house, not a lone half-tablet myth.
I felt flu-ish and itchy the night after oncho treatment. Did the chips fail?
More often they worked. Mazzotti is dying microfilariae - itch, ache, low fever, tender nodes - usually early. It settles. Failure looks like larvae that never fell, not a rough night. Urgent if breathing is hard, swelling is violent, or the mind changes, especially with a Loa map. A rough night after a heavy skin load is in the textbook. A forum cannot sort those two. If the eyes scare you, you are not still in the teaching margin. You are in a clinic.
Where do I go if I want the story or the trials instead of the arithmetic?
Story and receipt: how Kawana priced the 3 mg chip. Ledger: why COVID never bought a virus row. Molecule: Stromectol 3 mg. Come back here when you have kilograms and a named worm. I will not count chips for a headline, and I will not turn this count into a cart. Bring the arithmetic to the person who can see you.
General education from a clinician, not personal medical advice. Bring your own history to your own prescriber.
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