What the number means

The cumulative dose is the total amount of isotretinoin that you take over a whole course. It is counted in milligrams for each kilogram of body weight (mg/kg). Doctors use it because the total amount can matter as much as the daily amount.

A course of isotretinoin does not end on a fixed date for everyone. Your clinician looks at how your skin responds, how you tolerate the drug, and your total dose so far. Your clinician sets your target based on your response and tolerability.

How to use the calculator

Enter your information in the tool above. It does the math for you.

  • Enter your body weight in kilograms.
  • Enter your daily dose in milligrams, as your clinician prescribed.
  • Enter the number of days you have taken the daily dose entered above.

The tool shows your total dose in milligrams and your cumulative dose in milligrams per kilogram.

An example

The tool does the arithmetic, but here is the idea. If you take a daily dose for a number of days, your total is the daily dose multiplied by the days. Divide the total by your body weight to get mg/kg. The numbers in your own plan come from your clinician, not from this page.

Limits of this tool

  • It is an estimate. It does not know your health history.
  • It does not replace your clinician. Do not change your dose because of this number.
  • It does not know if you missed doses, or if your dose changed during treatment.
  • A target range is not a promise. Some people clear their skin with a lower total. Some need a different plan.

If your result looks different from what your clinician told you, ask them. Do not guess.

Safety reminders

Isotretinoin needs regular bloodwork. It also needs pregnancy tests for patients who can become pregnant, and the manufacturer's pregnancy prevention program applies. Your clinician explains these steps before they prescribe.

Read more about this treatment on our isotretinoin page. To check your daily dose, use the daily dose calculator.

Questions

Talk to your Care Team if you have a question about your dose. In an emergency, call 911. Modern Dermatology does not provide emergency care.