BMA Concise Guide to Medicine & Drugs


Brand names Isotrex Gel, Roaccutane

Used in the following combined preparation Isotrexin


Drug group Drug for acne

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes


Isotretinoin, a drug that is chemically related to vitamin A, is prescribed for the treatment of severe acne that has failed to respond to other treatments.

The drug reduces production of the skin’s natural oils (sebum) and of the horny protein (keratin) in the outer layers of the skin, making it useful in conditions such as ichthyosis, in which the skin thickens abnormally, causing scaling.

A single 16-week course of treatment often clears the acne. The skin may be very dry, flaky, and itchy at first, but this usually improves as treatment continues. Serious adverse effects include liver damage and bowel inflammation.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Capsules, gel.

Frequency and timing of doses 1–2 x daily (take capsules with food or milk).

Adult dosage range Dosage is determined individually.

Onset of effect 2–4 weeks (capsules); 6–8 weeks (gel). Acne may worsen initially in some people but usually improves in 7–10 days.

Duration of action Effects persist for several weeks after the drug is stopped. Acne is usually completely cleared.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children. Protect from light.

Missed dose Take as soon as you remember. If your next dose is due within 4 hours, take a single dose now and skip the next.

Stopping the drug Can be safely stopped as soon as you no longer need it, but best results are achieved when the course of treatment is completed as prescribed.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may cause headaches, vomiting, abdominal pain, facial flushing, incoordination, and dizziness. Notify your doctor.


The most serious adverse effects occur with the capsules. Dry nose, mouth, and eyes, inflamed lips, nosebleeds, and dry, flaking skin often occur. Mood changes, skin pigmentation changes, muscle or joint pain, and temporary loss or increase of hair may also occur. If headache, nausea, vomiting, blood in the faeces, visual impairment, rash, or unusual bruising occur, consult your doctor promptly. If abdominal pain or diarrhoea occur, stop taking the drug and consult your doctor immediately.


Tetracycline antibiotics increase the risk of high pressure in the skull, leading to headaches, nausea, and vomiting.

Skin-drying preparations Medicated cosmetics, soaps, and toiletries, and anti-acne or abrasive skin preparations increase the likelihood of dryness and irritation of the skin with isotretinoin.

Vitamin A supplements increase the risk of adverse effects from isotretinoin.

Progestogen-only contraceptives work poorly during isotretinoin treatment. Women should use an alternative method of contraception for one month before, during, and for one month after, treatment.


Do not donate blood during, or for at least a month after, taking oral isotretinoin. Be sure to tell your doctor if:

· You have long-term liver or kidney problems.

· You suffer from arthritis or gout.

· You have diabetes.

· You have a history of depression.

· You have fructose intolerance.

· You have high blood fat levels.

· You wear contact lenses.

· You are pregnant or planning a pregnancy.

· You are taking other medicines.

Pregnancy Must not be prescribed. The drug causes abnormalities in the developing baby. All women of child bearing age must use effective contraception for 1 month before, during, and 1 month after treatment.

Breast-feeding The drug is likely to pass into the breast milk and may affect the baby. Discuss with your doctor.

Infants and children Not prescribed.

Over 60 Not usually prescribed.

Driving and hazardous work Avoid such activities until you have learned how the drug affects you because it can cause vision problems in dim light or darkness.

Alcohol Regular heavy drinking may raise blood fat levels with isotretinoin.

Sunlight and sunbeds Avoid exposure: use a sunscreen or sunblock; do not use a sunlamp or sunbed.


Treatment rarely exceeds 16 weeks. Prolonged use may raise blood fat levels, and increase the risk of heart and blood vessel disease. Bone changes may occur.

Monitoring Liver function tests and checks on blood fat levels are performed.