Yesterday I was prescribed a course of 21 tabs x 200 mg x 3 times a day by my dentist for a tooth infection. I took 2 yesterday and by last night I noticed an itchy rash on one arm. I have not taken any more having consulted my dentist today and he has prescribed me am alternative anti-biotic. Despite having only taken 2 tablets, 24 hours later I am covered in a rash which has made my skin lumpy and very itchy.