Oral trimethoprim is an effective, relatively safe, long-term antibiotic for treatment of acne, according to Professor William Cunliffe and colleagues (department of dermatology, Leeds General infirmary).
In a letter to the British Journal of Dermatology (1999;141:747), they describe an open retrospective study of 396 male and 215 female acne patients who had failed to respond to two "adequate" courses of oral antibiotics. Patients then received trimethoprim 300mg twice daily for an average of eight months. Topical therapy was also applied, either as benzoyl peroxide, topical retinoid or Benzamycin (benzoyl peroxide and erythromycin) gel.
Of the 611 patients, 402 (66 per cent) remained on this treatment for eight months and showed significant improvement in their acne. Of the others, treatment was discontinued in 177 (29 per cent) because they had no response after four months.
Other discontinuations involved 29 patients (5 per cent) who stopped treatment because they developed a rash and three who had headache and dizziness. The most frequently experienced side effects were mild and included dyspepsia, nausea and vaginal candidiasis.
The authors say that resistance rates in their clinics to other acne treatments, such as tetracycline, erythromycin and clindamycin are 22 per cent, 67 per cent and 67 per cent, respectively, compared with 8 per cent for trimethoprim and they recommend the use of trimethoprim as a third-line agent.