logo Oral therapy for acne and rosacea

Follicular skin diseases

Oral therapy for acne and rosacea


  • Prescribe oral antibiotics for acne and rosacea appropriately and safely.
  • Understand indications for isotretinoin and its common adverse effects.

Key points

  • Tetracyclines, macrolides and sometimes other antibiotics are routinely prescribed for inflammatory acne and rosacea.
  • Tetracycline and its derivatives reduce the number of pathogenic bacteria and have anti-inflammatory actions.
  • The same antibacterial should be prescribed for at least 3 to 6 months.
  • In acne, oral antibiotics should be combined with a topical retinoid or benzoyl peroxide.
  • Other chronic skin diseases routinely treated with antibiotics include folliculitis and immmunobullous diseases.
  • Tetracyclines can be replaced by erythromycin in pregnancy and in children because of potential to stain dental enamel.
  • The most common adverse effects of tetracyclines are candidiasis, oesophagitis and photosensitivity.
  • Isotretinoin is an extremely effective treatment for acne.
  • Systemic retinoids are teratogenic.
  • Systemic retinoids cause mucocutaneous side effects.
  • Oral contraceptives can be prescribed for female acne, especially in the presence of polycystic ovarian syndrome.
  • Oral contraptives containing oestrogen should not be used for acne if there are significant risk factors for thromboembolic disease.
  • Antiandrogens prescribed for severe acne and hirsutism in women include cyclical cyproterone acetate and spironolactone.


This section will consider the use of the following oral agents:

Antibacterial agents

Systemic antibacterials for the treatment of moderate-to-severe acne and rosacea include tetracycline, doxycycline, minocycline, erythromycin and co-trimoxazole. They reduce the number of pathogenic organisms and they have anti-inflammatory actions, for example reducing Propionibacterium acnes-induced neutrophil chemotaxis and reactive-oxygen species.

Poor clinical response can be due to:

The same antibacterial should be prescribed for at least 3 months and usually for an average of 6 months. To prevent the development of resistance, they should be combined with a topical retinoid or benzoyl peroxide rather than a topical antibiotic. Systemic isotretinoin should be considered if one or two antibacterials have been tried without success.

Other chronic skin diseases routinely treated with antibiotics include:

Antibiotics are used empirically in these conditions. There are very few published randomised blinded trials to support their use, but benefit is generally self-evident in practice. Mostly the mechanism of action is unknown; probably an anti-inflammatory effect in most conditions but antimicrobial action may be important in others.

Tetracyclines are particularly useful as they are well tolerated and generally safe when used long term. In children and pregnant females it can be replaced by erythromycin, but this is probably less effective and has important interactions with other drugs. Because of a higher risk of serious adverse events, cotrimoxazole is rarely indicated.

Hypersensitivity to tetracyclines may result in:

Other adverse effects include:


Isotretinoin is an extremely effective treatment for acne and appears to work by reducing sebum production. The indications are

It is also used for antibiotic-resistant rosacea, folliculitis and rarely other inflammatory skin diseases. In New Zealand Pharmaceutical Schedule subsidy requires Special Authority application.

It has numerous side effects primarily mucocutaneous dryness.

Paronychia due to systemic retinoid

Cheilitis due to isotretinoin

Impetigo in patient taking isotretinoin

A course of isotretinoin 0.5-1 mg/kg/day ranges from 4 to 12 months (usually 5 to 6 months) and may be repeated if necessary.

Hormonal treatment

Hormonal treatment is an alternative regimen in female acne, especially in the presence of polycystic ovarian syndrome or when oral contraception is desired.

Because of reduced risk of thromboembolic disease, second generation combined oral contraceptives should be tried initially (3 to 6-month course as a minimum). Progestogen-only pills are generally ineffective. Injected medroxyprogesterone tends to aggravate acne. Medsafe has a useful guide to prescribing oral contraceptives.

Anti-androgenic ‘pills’ have a combination of ethinyl estradiol and progestins such as cyproterone acetate. The result is reduced seborrhoea in 80% of users, improvement in acne (up to 70%), in hirsutism (up to 40%) and androgen-related alopecia (up to 80%). They are generally well tolerated, the main adverse effects being nonspecific or as expected (headache, breast tenderness and nausea). They have no clinically relevant effects on metabolic or liver functions or on bodyweight.

Larger doses of cyproterone are sometimes used to treat hirsutism and polycystic ovarian syndrome but are rarely necessary for acne. Each cycle, 50-200mg is taken for 10 days and is usually combined with an oral contraceptive. Main adverse effects are menstrual irregularities, weight increase and depression.

Spironolactone also has antiandrogenic effects. It is used to treat female acne and hirsutism at a dose of 50 to 200mg daily. Main adverse effects are breast pain and menstrual irregularities (combine with oral contraceptive agent).