Welcome to the forum. Thanks for your question.
Gastrointestinal side effects (nausea, vomiting
, stomach cramps, diarrhea) are quite common following azithromycin (Zithromax). However, the drug still remains completely effective against chlamydia, unless there is vomiting immediately after taking it (within 30 minutes). Any longer than that, and enough drug is absored into the system to cure chlamydia.