Isotretinoin Dose Calculator

Estimate daily dose, per-dose amount, and total course length from body weight, a mg/kg/day dosing rate, and a cumulative mg/kg treatment target.

Quick Facts

Typical daily dose
0.5-1.0 mg/kg/day
Therapy is often started near 0.5 mg/kg/day and may be titrated as tolerated.
Typical cumulative target
120-150 mg/kg total
A commonly cited total-course exposure range from the dermatology literature.

Your Results

Calculated
Daily dose
-
Weight x mg/kg/day
Per-dose amount
-
Daily dose / frequency
Total cumulative dose
-
Weight x cumulative target
Estimated course length
-
Cumulative dose / daily dose

Ready

Enter body weight, daily dosing rate, and cumulative target, then calculate.

About the isotretinoin dose calculation

Isotretinoin (formerly branded Accutane) is dosed by body weight, using a daily dose expressed in milligrams per kilogram per day (mg/kg/day) and a cumulative total-course target expressed in milligrams per kilogram (mg/kg). This calculator performs that weight-based arithmetic - it multiplies your entered weight by a daily dosing rate and by a cumulative target to estimate a daily dose, a per-dose amount, and how long a course would take to reach the target at that daily rate.

How the calculation works

  • Daily dose (mg/day) = body weight (kg) x daily dose rate (mg/kg/day).
  • Per-dose amount (mg) = daily dose divided by the number of doses per day (once or twice daily).
  • Total cumulative dose (mg) = body weight (kg) x cumulative target (mg/kg).
  • Estimated course length = total cumulative dose divided by the daily dose, converted from days into weeks and months.

Putting the result in context

A daily dose of roughly 0.5 to 1.0 mg/kg/day and a cumulative target near 120 to 150 mg/kg are commonly referenced starting points in the dermatology literature, but the dose rate, target, and pace used for an actual course are set by the prescribing clinician based on the individual patient, tolerability, and lab monitoring - not by this calculator. Changing either the daily rate or the cumulative target changes the estimated course length, since a higher daily rate reaches the same total sooner.

When to consult a professional

This tool performs weight-based dosing arithmetic only; it is not a prescription, dosing recommendation, or substitute for medical supervision. Isotretinoin requires prescription, monitoring, and program enrollment through a licensed healthcare provider - use this calculator only to check arithmetic on a plan already discussed with that provider.

Frequently Asked Questions

What formula does this calculator use?
Daily dose (mg/day) equals body weight in kg multiplied by the chosen dose rate in mg/kg/day. Total cumulative dose (mg) equals body weight multiplied by the cumulative mg/kg target. Estimated course length in days equals the cumulative total divided by the daily dose, which is then converted to weeks and months.
What cumulative dose target is typically used for isotretinoin therapy?
A cumulative target of roughly 120 to 150 mg/kg over the full course is commonly cited in dermatology literature as associated with durable results. Prescribers set the actual target and pace for an individual patient; this calculator only performs the arithmetic once a target is entered.
Why does the estimated course length change with the daily dose?
Course length is the cumulative target divided by the daily dose, so a higher daily mg/kg/day rate reaches the same cumulative total in fewer days, while a lower daily rate stretches the same total over more weeks or months.

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