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.