Can I take azithromycin if I'm allergic to penicillin?
Azithromycin does not contain penicillin. At least one study I read found that patients who were allergic to penicillin did not have any reaction when taking azithromycin, so you should be fine. If you have concerns about it, you should call your pharmacist to make sure.
Here are some other articles about allergic reactions and antibiotics that you may find useful in your quest for good health.
Q & A on Drug Reactions: Was It an Allergic or Non-Allergic Type of Reaction
The Truth about Antibiotics: Myth vs. Fact