What is the total cumulative dose of Accutane (isotretinoin)?

The recommended total cumulative dose of isotretinoin is 120–150 mg/kg. For a 70 kg patient this means 8,400–10,500 mg total over the full course. Reaching this target is associated with the lowest relapse rates. Some dermatologists use cumulative doses up to 220 mg/kg for severe or recurrent acne.

How long does an Accutane course last?

A typical isotretinoin course lasts 5–7 months depending on the daily dose and patient weight. At 1 mg/kg/day (e.g., 70 mg/day for a 70 kg patient), the 120 mg/kg target is reached in about 4 months, while at 0.5 mg/kg/day it takes approximately 8 months. Most courses run 15–20 weeks minimum.

How is the Accutane cumulative dose calculated?

Cumulative dose (mg) = daily dose (mg) × number of days on treatment. To express as mg/kg, divide by patient weight in kg. For example, 40 mg/day × 180 days = 7,200 mg total. For a 70 kg patient that equals 7,200 ÷ 70 = 102.9 mg/kg cumulative dose.

What happens if you don't reach the cumulative dose?

Patients who do not reach a cumulative dose of at least 120 mg/kg have significantly higher relapse rates — up to 40% compared to approximately 20% for those reaching 120–150 mg/kg. However, even sub-therapeutic courses provide some benefit and a second course can be considered after a rest period.

What is low-dose isotretinoin and when is it used?

Low-dose isotretinoin (0.25–0.5 mg/kg/day or 10–20 mg/day) is used for mild-to-moderate acne, adult female acne, or patients who cannot tolerate standard doses. Treatment duration is longer (often 9–12 months) to reach adequate cumulative dosing. Studies show comparable long-term results with fewer side effects.

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Accutane (Isotretinoin) Cumulative Dose Calculator

Calculate your isotretinoin cumulative dose target, track treatment progress, and estimate remaining duration. Based on AAD guideline recommendations of 120–150 mg/kg total cumulative dosing.

Inputs

Patient Weight

Daily Dose (mg)

Target Cumulative Dose

Treatment Already Completed (optional — leave 0 if starting)

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Enter weight and daily dose to calculate.

Disclaimer: For educational purposes only. Isotretinoin prescribing requires enrollment in the iPLEDGE program (US) and regular monitoring. Not a substitute for clinical judgment.

When to use

This calculator helps dermatologists and clinicians determine the total isotretinoin cumulative dose target, estimate treatment duration, and monitor mid-course progress toward the guideline-recommended 120–150 mg/kg goal.

Dosing overview

Standard dose: 0.5–1.0 mg/kg/day, typically starting at 0.5 mg/kg/day for the first month then increasing.
Low-dose protocols: 0.25–0.5 mg/kg/day (10–20 mg/day) for mild acne or poor tolerability — longer courses (9–12 months) needed to reach cumulative target.
Cumulative target: 120–150 mg/kg total for lowest relapse rates; some use up to 220 mg/kg for severe/recurrent disease.
Typical course: 5–7 months at standard dosing (15–20 weeks minimum).

Clinical pearls

A cumulative dose <120 mg/kg is associated with relapse rates up to 40%.
Reaching 120–150 mg/kg reduces relapse to ~20%.
Higher cumulative doses (150–220 mg/kg) may further reduce relapse in severe cases.
Monitor CBC, lipids, LFTs, and pregnancy status throughout treatment.
Isotretinoin is a Category X teratogen — iPLEDGE compliance is mandatory in the US.

Relapse Risk by Cumulative Dose

Cumulative Dose	Relapse Risk	Notes
<120 mg/kg	Higher (~40%)	Below recommended target
120–150 mg/kg	Optimal (~20%)	AAD recommended range
150–220 mg/kg	Lower	Used for severe/recurrent acne
>220 mg/kg	Diminishing returns	Increased side effect burden

References

Strauss JS, et al. Guidelines of care for acne vulgaris management. J Am Acad Dermatol. 2007;56(4):651-663.
Blasiak RC, et al. Analysis of the cumulative isotretinoin dose and relapse rates. J Am Acad Dermatol. 2013;69(3):e133-e134.
Rademaker M. Isotretinoin: dose, duration, and relapse. Australas J Dermatol. 2010;51(3):175-180.
iPLEDGE REMS Program. ipledgeprogram.com

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About This Tool

What Is Isotretinoin Cumulative Dosing?

Isotretinoin (brand names: Accutane, Absorica, Claravis, Myorisan, Zenatane) is a systemic retinoid used for severe nodular acne and acne unresponsive to conventional therapies. The cumulative dose refers to the total amount of isotretinoin received over the entire treatment course, measured in mg/kg of body weight. Research consistently shows that reaching an adequate cumulative dose is the most important factor in preventing relapse.

Why Cumulative Dose Matters

Unlike many medications where daily dosing determines efficacy, isotretinoin's long-term success depends on the total amount received. The American Academy of Dermatology (AAD) recommends a cumulative dose of 120–150 mg/kg for the lowest relapse rates. This target was established by landmark studies showing:

<120 mg/kg: Relapse rates of 30–40% — often requiring a second course
120–150 mg/kg: Relapse rates drop to approximately 20%
>150 mg/kg: May further reduce relapse in selected patients, with diminishing returns above 220 mg/kg

How to Calculate

The formula is straightforward:

Cumulative dose (mg) = daily dose (mg) × total days of treatment
Cumulative dose (mg/kg) = total dose (mg) ÷ body weight (kg)
Duration to target = target total dose (mg) ÷ [daily dose (mg) × 30 days/month]

For example, a 70 kg patient taking 40 mg/day: target = 70 × 120 = 8,400 mg (low end). At 40 mg/day × 30 = 1,200 mg/month, this requires 8,400 ÷ 1,200 = 7 months to reach the minimum target.

Standard vs. Low-Dose Protocols

Standard dosing (0.5–1.0 mg/kg/day) is the most studied approach. Most dermatologists start at 0.5 mg/kg/day for the first month and titrate up to 1.0 mg/kg/day as tolerated, completing the course in 5–7 months.

Low-dose protocols (0.25–0.5 mg/kg/day) are increasingly popular for:

Mild-to-moderate acne not responding to topicals and antibiotics
Adult female hormonal acne
Patients with dose-limiting side effects (severe dryness, myalgia)
Patients who prefer fewer laboratory monitoring requirements

Low-dose courses typically last 9–12 months but achieve similar cumulative doses and comparable long-term outcomes with fewer mucocutaneous side effects.

🔑 Clinical Pearls

Weight changes during treatment affect the cumulative mg/kg calculation — recheck weight at follow-up visits.
Missed doses reduce cumulative dosing — counsel patients on adherence and take with a fatty meal for optimal absorption.
If side effects require dose reduction, extend the course duration rather than stopping early.
Wait at least 6 months after completing a course before considering retreatment — acne continues to improve post-treatment.
Isotretinoin absorption increases 2× when taken with a high-fat meal (≥20 g fat).

iPLEDGE Program (United States)

In the United States, all isotretinoin prescribing must comply with the iPLEDGE REMS program, which requires prescriber registration, monthly patient pregnancy testing (for those who can become pregnant), and dispensing within a 7-day window. This calculator helps with dosing planning but does not replace iPLEDGE compliance requirements.

Key References

Strauss JS, Krowchuk DP, Leyden JJ, et al. Guidelines of care for acne vulgaris management. J Am Acad Dermatol. 2007;56(4):651-663.
Blasiak RC, Stamey CR, Burkhart CN, et al. 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.
Rademaker M. Isotretinoin: dose, duration, and relapse. What does 30 years of usage tell us? Australas J Dermatol. 2010;51(3):175-180.
iPLEDGE REMS Program. ipledgeprogram.com

Formula last verified: February 2026