mild diarrhea, gas, stomach
pain; nausea or vomiting; headache; or skin rash or itching.
Are there other signs or symptoms present? Is he still taking augmentin? Stop using this medication and call your doctor at once if there is diarrhea that is severe or lasts longer than 3 days, nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, or jaundice. If it persists, it would be best to have this evaluated further by your doctor.
Take care and regards.