20 mg is a strength, not a course
Claim at the counter: 'I was put on Accutane 20 mg, so that is my dose.' Label the arithmetic. 20 mg is one capsule size. Daily need follows body weight. The finish line is a cumulative mg/kg total.
| Body weight | Start ~0.5 mg/kg/day | Toward ~1.0 mg/kg/day | 20 mg capsules at target |
|---|---|---|---|
| 50 kg | ~25 mg/day | ~50 mg/day | two and a half |
| 60 kg | ~30 mg/day | ~60 mg/day | three |
| 70 kg | ~35 mg/day | ~70 mg/day | three and a half |
| 80 kg | ~40 mg/day | ~80 mg/day | four |
| 90 kg | ~45 mg/day | ~90 mg/day | four and a half |
US practice typically starts near 0.5 mg per kilogram per day and builds toward about 1.0 mg per kilogram per day as tolerated, often split into two swallows, for something like 15 to 20 weeks if the total can be reached in that window. A 70 kg person at 1.0 mg/kg is looking at 70 mg a day - that is three-and-a-half 20 mg capsules, not 'a 20 mg course.' Some clinicians start lower when inflammation is explosive, then climb once the early flare settles.
Daily milligrams alone do not predict a lasting quiet. The running sum does. Pharmacology of absorption and clearance is on the Accutane 20 mg reference. Habit on this card: pin the daily figure to kilograms, then track how many 20 mg capsules have actually been swallowed toward the total.
The pregnancy hold sits above the arithmetic
Isotretinoin is among the most powerful human teratogens in the cabinet. Taken during pregnancy, even briefly: severe defects of skull, face, heart, thymus, and brain, plus a sharp rise in miscarriage. No safe dose. No safe week. This is not a caution you weigh against clearer skin. It is a hold. Anyone pregnant, or who could become pregnant during treatment and for a month after the last capsule, does not start unless pregnancy is fully prevented.
Because the hold is absolute, the United States wraps every fill in iPLEDGE. Patients who can become pregnant use two contraception methods at once, starting the month before the first capsule and continuing a month after the last, and they document a negative pregnancy test every month before the next bottle is released. Pickup sits inside a short window after that test. Miss the window and the order does not print. Regulator text is at the FDA.
Do not bargain the hold against a prettier cumulative total. A perfect 150 mg/kg course that exposed a pregnancy is not a success. The 20 mg arithmetic only starts after the registry says the month is clear.
The running total that predicts stay-clear
Claim: stop when the mirror is quiet. Strike it. The figure that best predicts whether nodules stay gone is the total drug accumulated - about 120 to 150 mg per kilogram across the whole course.
| Body weight | 120 mg/kg total | 150 mg/kg total | 20 mg capsules to 120 mg/kg |
|---|---|---|---|
| 50 kg | 6,000 mg | 7,500 mg | 300 |
| 60 kg | 7,200 mg | 9,000 mg | 360 |
| 70 kg | 8,400 mg | 10,500 mg | 420 |
| 80 kg | 9,600 mg | 12,000 mg | 480 |
| 90 kg | 10,800 mg | 13,500 mg | 540 |
Skin often looks clear well before that total. Stop at week eight because the photos are good and you have under-dosed the course. Relapse is then a scheduling error, not a mysterious failure. Dermatologists keep going - often five to six months - because the running sum is the lever. Lower totals can clear in the short run and come back more often.
Arithmetic is blunt. A 70 kg person aiming at 130 mg/kg needs about 9,100 mg total. At 70 mg/day that is roughly 130 days. In 20 mg capsules, that is hundreds of swallows, not a short blister. Stopping short of the cumulative target is the common avoidable reason a second course appears. Why total beats early clearing is tied to the nodular trial file.
Fat on the plate is part of the dose
Standard isotretinoin is absorbed far better with food that actually contains fat. Empty stomach: a large part of the 20 mg capsule never makes it in. Same count, smaller exposure. Most versions say take with a meal that has fat. That roughly doubles uptake versus fasting, so the blood level matches the dosing assumptions on the card.
Exception: Absorica, built to absorb more predictably without a fatty meal. Its instructions differ. Unless you are on that formulation and were told otherwise, treat food as part of the milligram. Quiet fasting is a way to miss the cumulative target while believing you took every capsule. The bottle lied only because the plate was empty.
Dryness and labs are expected marks
Claim: side effects mean the course is going wrong. Strike it. Nearly everyone dries out. Blood gets checked. Both are routine marks, not a reason to panic on day twelve.
| Mark | When | Why it sits on the card |
|---|---|---|
| Pregnancy test | Monthly, before each supply | Hold: no pregnancy on the drug |
| Lipids, especially triglycerides | Baseline, then periodic | The capsule can raise blood fats |
| Liver enzymes | Baseline, then periodic | Can nudge LFTs |
| Lip balm and moisturizer | Daily, whole course | Dryness is near-universal |
| No tetracyclines | Whole course | Combined risk of raised skull pressure |
| No blood donation | On drug and one month after | Protect a recipient who could be pregnant |
Chapped, cracking lips are the signature. Lip balm becomes a pocket object. Dry skin, dry eyes, a dry nose that spots blood, sometimes dry mucosa elsewhere - expected, managed with moisturizer, balm, drops, and gentle care, not by abandoning an indicated course. Contact lenses often lose to glasses for a few months. Muscle and joint ache, reduced night vision, headache, and sun sensitivity also show up. A dangerous rise in skull pressure is rare - one reason this capsule is not paired with tetracycline antibiotics.
Labs are mostly lipids and liver. Triglycerides can climb. Enzymes can nudge. Baseline, then periodic checks. Most shifts are mild and reverse when the bottle ends. A sharp triglyceride rise is the one that may force a dose cut. Monthly pregnancy testing is a different species of lab - it is the hold, not a chemistry curiosity. The rest of the profile is on the Accutane 20 mg reference.
IPLEDGE windows are the refill lock
Plain again, because this is the line that does not move. The capsule must never be taken during pregnancy. Anyone who can become pregnant must prevent pregnancy completely through the course and the month after. That is the whole reason the registry exists. Two contraception methods together. A documented negative test every month before the next 20 mg supply. Pickup inside a short window. Miss the test or the window and the order stays in the computer.
Patients call it rigid. The rigidity is the safety mechanism working. If contraception, testing, or the monthly rhythm is not workable, that is a reason to choose a different acne path, not a hurdle to route around. Mayo Clinic's treatment overview is at Mayo Clinic. How the country arrived at a computer lock instead of a leaflet is the iPLEDGE origin line.
How to read the card in one sitting
A clean 20 mg course is a short list of habits. Dose by kilograms - start near 0.5 mg/kg/day, build toward 1.0 as tolerated. Count capsules toward a cumulative 120 to 150 mg/kg, not toward a prettier mirror. Swallow each standard capsule with a fatty meal unless you were specifically put on Absorica. Keep balm and moisturizer in reach. Show up for lipid and liver checks.
Hold the line that does not move: no pregnancy on this drug. Two contraception methods for anyone who can become pregnant. Negative test every month. Everything else is adjustable. That one rule is not. Right diagnosis, honest numbers, respect the monitoring, treat the contraindication as a hold - and the capsule still does what it has done since 1982: finish acne that nothing else would finish. Trial shape of that finish is in the nodular evidence line.