Penicillin is an antibiotic that is used to fight pathogenic bacteria in the human body, according to Drugs.com. This antibiotic is a common, wide-spread antibiotic that targets many different types of bacteria.
Penicillin should only be taken by individuals for whom it is prescribed, says Drugs.com. Patients should take the medication as prescribed and for the recommended length of time to completely rid the body of the bacteria. It can cause many different side effects, including diarrhea, fever, nausea, headache, thrush and easy bruising. The antibiotic may also interfere with the ability of other medications to work properly, including methotrexate and probenecid.