Comparison of gastrointestinal side effects from different doses of azithromycin for the treatment of gonorrhoea

OBJECTIVES: Azithromycin is commonly used to treat Neisseria gonorrhoeae. We compared its gastrointestinal side effects using 1 g single, 2 g single or 2 g split (i.e. 1 g plus 1 g 6–12 h later) dosing, representing our clinic’s changing guidelines over the study period. METHODS: We recruited consecutive sexual health clinic patients who received azithromycin (and 500 mg ceftriaxone) for uncomplicated gonorrhoea. Each patient received a text message 48 h after their attendance to complete a questionnaire. RESULTS: Patients received 1 g single (n = 271), 2 g single (218) or 2 g split (105) doses. Vomiting was less common for 1 g versus 2 g single dose [1.1% versus 3.7%; risk difference (RD): −2.6%; 95% CI: −0.2 to −5.4] and 2 g split versus 2 g single dose (0.9% versus 3.7%; RD: −2.8%; 95% CI: −0.3 to −5.8). Nausea was less common for 1 g versus 2 g single dose (13.7% versus 43.1%; RD: −29.5%; 95% CI: −21.7 to −37.2) and 2 g split versus 2 g single dose (16.4% versus 43.1%; RD: −26.8; 95% CI: −17.2 to −36.3). Diarrhoea was less common for 1 g versus 2 g single dose (25.5% versus 50.9%; RD: −25.5%; 95% CI: −17.0 to −33.9) and 2 g split versus 2 g single dose (30.9% versus 50.9%; RD: −20.0; 95% CI: −9.1 to −30.9). Almost all were willing to retake the same dosing for gonorrhoea in the future: 97% for 1 g single; 94% for 2 g single; and 97% for 2 g split dose. CONCLUSIONS: Azithromycin 2 g split dose for gonorrhoea resulted in significantly less vomiting, nausea and diarrhoea than a 2 g single dose.