Amoxicillin side effects. Amoxicillin is a penicillin antibiotic used to treat bacterial infections, including bronchitis, pneumonia, and infections of the ear, nose, throat, skin, and urinary tract. Applies to amoxicillin: oral capsule, oral powder for reconstitution, oral tablet, oral tablet chewable, oral tablet dispersible, oral tablet extended release General The most frequently reported side effects were diarrhea, nausea, and skin rash. Amoxicillin is a penicillin antibiotic treatment for a wide range of bacterial infections such as bronchitis, pneumonia and tonsillitis, as well as infections of the ear, nose, throat and urinary tract. Doctors give trusted, helpful answers on causes, diagnosis, symptoms, treatment, and more: Dr. Vanderloop on can antibiotics cause blisters: Try avoiding spicy and hot food. Amoxicillin is a form of penicillin, which is an antibiotic that treats numerous bacterial infections such as strep throat. Tell your doctor about all the other medications you are taking and any allergies so he can make sure amoxicillin is right for you. According to MayoClinic.com, a sore mouth is Amoxicillin, abbreviated amox, is a β-lactam antibiotic prescribed to deal with infectious bacteria. Like all antibiotics, there are some side effects that come along with amoxicillin, too. This Site Might Help You. RE: Should I stop taking amoxicillin if I get blisters in my mouth? I started taking this drug about 4 days ago and after the first 3 days I developed some sores inside my mouth. Doctors give unbiased, trusted information on whether Amoxicillin can cause or treat Mouth Pain: Dr. Lipkin on how to relieve a sore mouth from the side effects of amoxicillin: Prolonged time of taking Prednisone or steroid can cause change in appearance (cushingoid). Why are you on it? Necessity? These have to be weighed. Talk to your doctor for alternatives because once it is set in. Side Effects. Drug information provided by: IBM Micromedex. Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. Mouth sores are common ailments that affect many people at some point in their lives. These sores can appear on any of the soft tissues of your mouth, including your lips, cheeks, gums, tongue.