Does erythromycin cure chlamhydia in the mouth?

Not reliable: Chlamydia doesn't easily infect the oral cavity; it can happen but is uncommon. Erythromycin is a good drug for chlamydia but often fails anyway because it causes stomach upset and many people have trouble taking it for a week. The recommended drugs for chlamydia, anywhere in the body, are azithromycin (single dose) or doxycycline for a week. Check with your doctor, or the nearest NHS GUM clinic.