Which medication is primarily used as an alternative for patients allergic to penicillin?

Clindamycin is often prescribed as an alternative antibiotic for patients who are allergic to penicillin. It belongs to the lincosamide class of antibiotics and is effective against various bacterial infections, particularly those caused by anaerobic bacteria and certain strains of streptococci and staphylococci.

For patients with penicillin allergies, the choice of alternatives usually emphasizes medications that do not exhibit cross-reactivity with penicillin. Clindamycin has a different structure and mechanism of action compared to penicillins, making it a suitable option.

Other antibiotics, such as vancomycin, while useful for treating gram-positive infections, are typically reserved for more severe cases, including those caused by methicillin-resistant Staphylococcus aureus (MRSA). Amoxicillin is a penicillin derivative and would not be appropriate for someone with a penicillin allergy. Cephalexin is a first-generation cephalosporin, and there is a potential for cross-reactivity in patients with penicillin allergies, which also makes it less suitable as an alternative in such cases.