Antibiotics for acne

Antibiotics are commonly used to treat acne. They are available as topical preparations for mild acne and as tablets, capsules and elixirs for oral use in moderate and severe acne.

Mechanism of action

Antibiotics have two main effects in acne:

• Reduce the number of bacteria on the skin surface and in the follicles
• Anti-inflammatory action

Topical antibiotics

Topical antibiotics require a prescription in New Zealand.

• Clindamycin - Clinac® solution, Dalacin T® gel, lotion, solution, Topicil® solution & Duac® Once Daily gel
• Erythromycin - Stiemycin® solution, Eryacne® gel

Side effects

• Dryness of the treated area can be expected and is usually mild. If the skin is visibly scaly, apply a light non-oily moisturizer.
• Skin irritation is rarely severe. Occasionally, irritation means that product must be discontinued. Lotions are less likely than solutions or gels to cause irritation.
• Contact dermatitis (red, dry, itchy skin) can be due to irritancy or allergy. It can be treated with a topical steroid such as hydrocortisone cream (available at a NZ pharmacy without prescription).
• Bacterial resistance most frequently arises with intermittent use of topical antibiotics. To reduce this, apply topical antibiotics liberally twice daily and ideally combine with benzoyl peroxide &/or a topical retinoid.

Oral antibiotics

The oral antibiotics most commonly prescribed for acne include:

• Tetracycline – tetracycline (Panmycin®), minocycline (Mino-tabs®, Minomycin®), doxycycline (Doxine®, Doxy® & Doryx®), limecycline (Tetralysal®). These are not suitable for children younger than 10 years old because they may stain teeth yellow.
• Erythromycin - Emu-V®, Eryc®, Eromycin®, E-mycin®, EES® & ERA®
• Trimethroprim - Triprim® & TMP®
• Cotrimoxasole - Apo-Sulfatrim®, Trisul®, Trimel®, Bactrim® & Septrin®

Side effects and risks (see also, DermNet's page on tetracycline)

• Allergy - antibiotics can cause a variety of rashes in those susceptible. These can be mild or life-threateningly severe. Allergy to tetracycline or erythromycin is very uncommon but arises in more than 2% of those on trimethoprim or cotrimoxasole. Tell your doctor if you have ever reacted badly to an antibiotic.
• Photosensitivity may be a problem for those taking doxycycline. Taking the medicine after the evening meal reduces the risk of sunburn.
• Gastrointestinal disturbance affects about 5% and includes nausea, colicky pain and diarrhoea.
• Thrush (candidiasis) affects 5% of treated women and is most often vaginal. Thrush can affect the oral mucosa or body folds (intertrigo). It is less likely with erythromycin than with tetracycline.
• Bacterial resistance - most frequently arises with intermittent use of topical antibiotics. To reduce this, apply topical antibiotics liberally twice daily or combine with benzoyl peroxide or topical retinoids.
• Possible increased chance of failure of the oral contraceptive pill. The risk is very small.