Some commonly used antibiotics prescribed to cats can have hair loss as a side effect. Hair loss is typically mild and is a less common side effect than nausea, vomiting or diarrhea.
Tetracycline
Tetracycline is a broad spectrum antibiotic used in bacterial infections. In addition to hair loss, side effects include sensitivity to light, digestive problems, discolored teeth, and liver or kidney disease.
Metronidazole
This antibiotic is used to treat Giardia, anaerobes and diarrhea in cats. One side effect is neurological problems, which can manifest as excessive licking or chewing on the body, causing balding.
Trimethoprim Sulfa
This is a broad spectrum antibiotic that some cats have allergic reactions to, which can result in hair loss at an injection site or thinning of fur.
Allergic Dermatitis
Cats suffering from allergic dermatitis have a sensitivity to topical substances. This can occur with antibiotics and a sensitivity at injection sites. Thinning fur and itching at injection locations is common.
Medication Sensitivities
Drug sensitivity is common with penicillin, sulfonamide and cephalosporin antibiotics. Reactions, such as hair loss, typically occur within two weeks of administering the drug.
