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.

A doctor's prescription is required to obtain antibiotics. The antibiotics listed on this page were available in New Zealand in April 2014. Other antibiotics or brand names are available on prescription in other countries.

Mechanism of action of antibiotics in acne

Antibiotics have two main effects in acne:

• They reduce the number of bacteria on the skin surface and in the follicles, including Cutibacterium acnes (also known as Propionibacterium acnes)
• They have an anti-inflammatory action.

Topical antibiotics in acne

Topical antibiotics require a prescription in New Zealand.

• Clindamycin – ClindaTech® solution, Topicil® solution and Duac® Once Daily gel
• Erythromycin – Eryacne® gel

Side effects and risks of topical antibiotics

• Dryness of the treated area is usually mild but is a common side effect of topical antibiotics. If the skin is visibly scaly, apply a light non-oily moisturiser.
• Skin irritation from topical antibiotics is rarely severe. Occasionally, irritation means that the patient should stop using the product. Lotions are less likely to cause irritation than solutions or gels.
• Contact dermatitis (red, dry, itchy skin) can be due to irritancy or allergy. It can be treated with a topical corticosteroid such as hydrocortisone cream (available at a NZ pharmacy without prescription).
• Bacterial resistance to antibiotics most frequently arises with intermittent use of topical antibiotics. To reduce the chance of bacterial resistance, apply topical antibiotics liberally twice daily and also use benzoyl peroxide and/or a topical retinoid.

Oral antibiotics in acne

The oral antibiotics most commonly prescribed in New Zealand for acne include:

• Tetracyclines – doxycycline (Doxine®, Doxy®), limecycline (Tetralysal®), minocycline (Mino-tabs®, Minomycin®). These are not suitable for children younger than 10 years old because they may stain teeth yellow
• Erythromycin – E-mycin®, ERA®
• Trimethroprim – TMP®
• Cotrimoxazole – Trisul®, Deprim®

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

• Allergy – oral antibiotics can cause a variety of rashes in those susceptible. These can be mild or life-threateningly severe. Allergy to a tetracycline or to erythromycin is very uncommon, but more than 2% of those on trimethoprim or cotrimoxazole become allergic to it. 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. Dress up and protect your skin from exposure to the sun.
• Gastrointestinal disturbance affects about 5% of patients and includes nausea, colicky pain and diarrhoea.
• Thrush (Candida albicans infection) affects 5% of treated women and most often affects the vagina. Thrush can also affect the oral mucosa or body folds (intertrigo), particularly in diabetics or in obesity. Thrush is less likely with erythromycin than with tetracycline.
• Bacterial resistance may occur but is less common with the use of oral antibiotics than with topical antibiotics.
• Acne antibiotics are unlikely to result in failure of the oral contraceptive pill but if you are concerned, add a barrier method and talk to your doctor about your risks.

Controversies in use of antibiotics for acne

Antibiotics are moderately effective for acne and are frequently used for acne treatment. They are often prescribed for months or years, because acne is a chronic skin condition. However, many physicians are concerned about the use of antibiotics for acne, mainly because of reports of increasing rates of bacterial resistance to antibiotics.

Bacterial resistance and serious infections including cellulitis, pneumonia, tuberculosis and diarrhoeal illnesses are a global threat. New, more expensive antibiotics are often less well tolerated than older agents and are unavailable in many countries. Very few new antibiotics are being discovered or brought to market.

Note:

• Acne is an inflammatory disease and is not an infection. See DermNet NZ's Causes of acne page.
• Topical antibiotics are more likely to induce bacterial resistance than oral antibiotics.
• P. acnes bacterial resistance is common in people treated with antibiotics for acne, and the resistance can spread to their family members and neighbours.
• Resistance genes can spread from P. acnes to other types of bacteria such as Staphylococcus epidermidis and S. aureus.
• The prevalence of bacteria with multidrug resistance is increasing worldwide.
• Topical antibiotics alone are no more effective in acne than topical retinoids or benzoyl peroxide.
• Topical or systemic antibiotics should always be used in combination with benzoyl peroxide, a topical retinoid or azelaic acid. In women, they may also be used in combination with antiandrogen therapy or oral contraceptive pill.
• There have been no reports of bacterial resistance being caused by benzoyl peroxide. Benzoyl peroxide has been shown to reduce the prevalence of resistant strains of P. acnes.
• Topical antibiotics should not be used at the same time as oral antibiotics.
• The optimum dose and duration of treatment with oral antibiotics that can be given without inducing bacterial resistance is unknown.
• However, low-dose doxycycline (50 mg daily) is probably less likely to induce resistance than standard-dose doxycycline (100–200 mg daily) and may be as effective in controlling the acne.
• Oral antibiotics are known to act by reducing bacterial colonisation and inflammation in the affected follicles, but they do not cure acne.
• There is no benefit to switching antibiotics to improve efficacy in acne treatment. Switching may increase the risk of bacterial resistance.
• It may be necessary to change antibiotics in the case of adverse effects.
• Side effects from antibiotics are occasionally serious and may be long lasting. Serious adverse effects are more likely from minocycline than from doxycycline.

If you are prescribed antibiotics for acne, discuss these concerns with your doctor. Make sure your acne treatment is reviewed regularly. It's best to limit a course of antibiotics to 3 months, if possible. Apply topical benzoyl peroxide and/or a topical retinoid to areas affected by acne while on antibiotics and after they have been stopped. Find out if other, non-antibiotic treatment might be suitable for you.