Strep throat, also known as Group A Streptococcus Pharyngitis, is a bacterial infection that is caused by a group of bacteria called group A Streptococcus (GAS). If you are allergic to penicillin, your doctor will likely prescribe a different type of antibiotic. The choice of antibiotic will depend on your allergy, the severity of your infection, and other factors.

There are a few different types of antibiotics that can be used to treat strep throat if you are allergic to penicillin. These include:

1. Azithromycin (Zithromax) - This is a medication that belongs to a class of antibiotics known as macrolides. It is typically taken once a day for three days to treat strep throat.

2. Clindamycin - This is a medication that belongs to a class of antibiotics known as lincosamides. It is typically taken twice a day for 10 days to treat strep throat.

3. Erythromycin (Erythrocin) - This is a medication that belongs to a class of antibiotics known as macrolides. It is typically taken twice a day for 10 days to treat strep throat.

4. Telithromycin (Ketek) - This is a medication that belongs to a class of antibiotics known as ketolides. It is typically taken once a day for 5 days to treat strep throat.

5. Vancomycin - This is a medication that belongs to a class of antibiotics known as glycopeptides. It is typically given as an injection in the hospital to treat severe cases of strep throat.

It is important to note that strep throat can cause complications if it is not treated properly. These complications can include rheumatic fever, which can cause damage to the heart valves and other organs. If you suspect that you have strep throat, it is important to see your doctor right away so that they can determine the best course of treatment for you.