Clinical penicillin generally refers to penicillins, the use of which may cause nausea, as nausea is a common adverse reaction to penicillins. Penicillins are a class of antibiotics, including natural penicillins, enzyme-resistant penicillins, and broad-spectrum penicillins, which interfere with bacterial cell wall synthesis and act as bactericides during the bacterial reproduction phase. Common adverse reactions to penicillin antibiotics are nausea, vomiting, epigastric discomfort, diarrhea, etc. Therefore, nausea may occur after using penicillins, which is an adverse reaction to the medication and usually has mild symptoms. Penicillin is contraindicated in patients with a history of allergy to penicillins or a positive penicillin skin allergy test. Adverse reactions such as allergic reactions (e.g., rash, hives, anaphylaxis) and secondary infections may also occur with penicillin. The drug should be used under medical supervision.