Isotretinoin Calculator - mg/kg Dose and Course Length

An isotretinoin calculator turns body weight into the published prescribing arithmetic for severe nodulocystic acne. Isotretinoin, also called 13-cis-retinoic acid and marketed as Accutane, Claravis, Absorica, and Amnesteem, is dosed by body weight in mg per kg per day.

• • Pre-appointment dose worksheet: an adult starting isotretinoin enters current weight, prescribed mg per kg per day, and the planned cumulative target.
• • Course length estimator: a patient can estimate when they are likely to reach the 120 to 150 mg per kg cumulative endpoint.
• • Pill supply planning: a patient can estimate how many 10, 20, 30, or 40 mg capsules a full course will need for refills and travel supplies.
• • Pediatric or adolescent dose review with a caregiver: a parent of a teenager can repeat the calculation to keep weight and dose changes visible between visits.

Isotretinoin is reserved for severe nodulocystic or scarring acne, and it carries a boxed warning for severe birth defects. The US iPLEDGE program and parallel programs such as the UK PPP require pregnancy tests and two forms of contraception before each refill. The isotretinoin calculator supports the prescribing arithmetic but does not enroll anyone or replace the treating dermatologist.

Body weight is the single most important input. The BMI Calculator gives a quick body weight and height context.

Body weight is the single most important input, so the BMI Calculator gives a quick body weight and height context. For smaller or larger adults, the Ideal Body Weight Calculator shows the Devine and Robinson formulas that some dermatology protocols reference.

The calculation has three layers. The first turns body weight into the daily milligram amount, the second turns body weight into the cumulative total, and the third divides the cumulative total by the daily amount to estimate the course length.

• bodyWeightKg: actual body weight in kilograms, or pounds converted to kilograms by dividing by 2.2046226218
• dailyDosePerKg: the prescribed daily isotretinoin dose in mg per kg per day, normally 0.5 to 1 mg per kg per day
• cumulativeTargetPerKg: the planned cumulative isotretinoin target in mg per kg, most often 120 to 150 mg per kg
• pillStrength: the dispensed capsule strength in mg, used to translate cumulative mg into a capsule count

Pounds are converted to kilograms using the NIST pound-to-kilogram factor of 0.45359237, which equals 2.2046226218 pounds per kilogram. The course length in weeks equals the cumulative total divided by the daily dose divided by seven.

When a dose or cumulative target is entered outside the published range, the calculator clamps the value.

According to DailyMed Accutane (isotretinoin) FDA label, the recommended dosage is 0.5 to 1 mg per kg per day in two divided doses for 15 to 20 weeks, and the label carries a boxed warning for severe birth defects and requires enrollment in iPLEDGE for pregnancy prevention.

Four ideas drive the result. Naming them keeps the calculator from being used as a black box.

Cumulative dose framing matters because two patients on the same daily mg can have different total exposure, so both numbers are shown in the result.

Cumulative dose framing matters because two patients on the same daily mg can have different total exposure, and the GFR Calculator is a useful companion when kidney function is part of the prescribing conversation.

The form works from the body weight, the daily mg per kg, the cumulative mg per kg target, and the pill strength.

1. 1 Enter body weight: use the most recent measured body weight in kilograms or pounds. Pounds are converted to kilograms before the dose arithmetic runs.
2. 2 Enter the prescribed daily dose in mg per kg per day: use 0.5 mg per kg per day for the starting dose, or 1 mg per kg per day for the common steady-state dose.
3. 3 Enter the cumulative target in mg per kg: use 150 mg per kg for a standard AAD-style full course, or 120 mg per kg for a lower-end target.
4. 4 Enter the dispensed capsule strength: use 20 mg or 40 mg in the United States, 5, 10, 20, or 40 mg in other markets. The pill count is rounded up so the patient does not run out.
5. 5 Read the dose, cumulative total, and course length: the result panel shows the daily mg, the cumulative total, the course length in days and weeks, the daily capsule count, and the total capsule count.
6. 6 Bring the result to the dermatology visit: share the daily mg, cumulative target, and course length estimate with the prescribing dermatologist so any dose change is recorded.

A 60 kg adult is started on isotretinoin at 0.5 mg per kg per day and then titrated to 1 mg per kg per day. At a 150 mg per kg cumulative target, the published endpoint is 9,000 mg total.

A 60 kg adult starting at 0.5 mg per kg per day reaches the same 150 mg per kg endpoint about half as fast as a 60 kg adult at 1 mg per kg per day. The Adjusted Weight Calculator explains when actual, ideal, or adjusted weight is used in clinical dose review.

Using the published mg per kg arithmetic in a structured way has practical advantages for patients, caregivers, and dermatology teams.

• • A daily milligram amount in seconds: the form turns the published mg per kg per day dose and the current body weight into a daily milligram amount.
• • A course length that matches the published label: the estimated course length in days and weeks is computed from the cumulative target.
• • A pill count for refill planning: the total capsule count is rounded up, which makes iPLEDGE and pharmacy refill planning easier.
• • Visible weight changes between visits: body weight can change during a course, and re-entering the new weight shows how the numbers move.
• • Shared language with the dermatology team: the same mg per kg per day, mg per kg cumulative, and weeks-of-therapy values are used in adult clinics.
• • Sensitive framing of pregnancy-prevention context: the result reminds the user that isotretinoin requires iPLEDGE or a parallel program, without enrolling the user.

The calculator is most useful when it is run more than once, comparing the starting and titrated dose.

The Hydroxychloroquine Dose Calculator applies a similar mg per kg per day approach to a different prescription.

The result depends on the entered body weight and the two prescribing decisions, but a few clinical factors can shift the interpretation without changing the arithmetic.

• • The calculator does not replace a dermatology visit, an iPLEDGE or REMS enrollment, a pregnancy test, or a lipid and liver monitoring plan.
• • The mg per kg per day range is based on the DailyMed Accutane label and the AAD patient guidance. Some severe acne protocols use different ranges.
• • The pill count is rounded up to the next whole capsule, but isotretinoin is also dispensed in blister packs or compounded preparations in some markets.

Relapse risk is a common reason dermatology teams target the higher end of the published cumulative range, according to the British Association of Dermatologists.

According to American Academy of Dermatology - Isotretinoin, isotretinoin is a powerful treatment for severe nodulocystic acne, is taken for about 15 to 20 weeks, and requires a strict pregnancy-prevention program because of the risk of severe birth defects.

According to British Association of Dermatologists - Isotretinoin, isotretinoin is usually prescribed at 0.5 to 1 mg per kg per day for 4 to 6 months, and a total cumulative dose target is used to reduce the risk of acne relapse after treatment ends.

For a broader label-band comparison outside prescription isotretinoin, the Aleve Dosage Calculator shows the same kind of dose-limit calculation for naproxen sodium.