How it's calculated
Daily dose (mg) = weight (kg) × dose per kg (mg/kg/day), usually given in 2 divided doses with food. Estimated course duration = target cumulative dose (weight × mg/kg target) ÷ daily dose.
Reference dosing ranges
| Parameter | Typical range |
|---|---|
| Daily dose | 0.5-1.0 mg/kg/day (low-dose regimens use 0.25-0.4 mg/kg/day) |
| Cumulative target dose | 120-150 mg/kg over the full course |
| Typical course length | ~15-20 weeks (4-5 months) |
Clinical use
- Common capsule strengths: 10 mg, 20 mg, 30 mg, and 40 mg (availability varies by country/brand).
- Isotretinoin is absorbed better with a fatty meal — advise taking each dose with food to improve bioavailability.
- Lower-dose, longer-duration regimens (e.g. 0.25-0.4 mg/kg/day) are increasingly used to reduce mucocutaneous side effects while still reaching an adequate cumulative dose, particularly for milder or moderate acne.
- Regular monitoring is required during treatment: baseline and periodic lipid profile and liver function tests, and pregnancy testing at baseline and monthly intervals in patients who can become pregnant.
Frequently asked questions
What is the standard isotretinoin dosing regimen?
Typically 0.5-1.0 mg/kg/day in two divided doses with food, continued until a cumulative target dose of approximately 120-150 mg/kg is reached, usually over about 15-20 weeks.
Why does isotretinoin use a cumulative dose target rather than just a fixed duration?
Relapse rates are more closely linked to total cumulative exposure than to a fixed number of weeks, so treatment is typically continued until the calculated cumulative target is reached rather than stopped after a set duration alone.
Is isotretinoin safe in pregnancy?
No — it is a proven teratogen and is contraindicated in pregnancy. Reliable contraception (two forms) and regular pregnancy testing are required throughout treatment and for one month after stopping, per iPLEDGE or equivalent regional risk-management programmes.
What monitoring is needed during treatment?
Baseline and periodic lipid profile and liver function tests are standard, alongside monthly pregnancy testing where applicable — frequency of blood testing varies by local protocol and patient risk factors.
References
- Zaenglein AL, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2016;74(5):945-973.e33.
- Isotretinoin FDA Prescribing Information (Accutane/generic) — Dosage and Administration.
- Blasiak RC, Stamey CR, Burkhart CN, Lugo-Somolinos A, Morrell DS. High-dose isotretinoin treatment and the rate of retrial, relapse, and adverse effects in patients with acne vulgaris. JAMA Dermatol. 2013;149(12):1392-1398.