Moderate
Azithromycin × Theophylline
Macrolides×Methylxanthine
Mechanism
Azithromycin is a weak CYP1A2 inhibitor (theophylline is a substrate). Theophylline plasma levels may rise slightly. The effect is much smaller than with erythromycin or clarithromycin.
Symptoms
Mostly no changes. In patients with borderline theophylline levels: rare nausea, tachycardia, insomnia.
Management
For short azithromycin courses (3–5 days), no special adjustment. In patients on high theophylline doses (or with renal/hepatic impairment): check theophylline level at 3–5 days.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.