Could penicillin make my period late?

[Cuddlecakes]

Recently I had tonsillitis and took a course of penicillin for 1 week. Shortly after that I had unprotected sex with my boyfriend but he withdrew before ejaculation. I am not on any form of birth control and my period is about 4 days date, today I took an Asda pregnancy test which gave a negative result. I'm going to take another one tomorrow morning when my urine is more concentrated but is it possible that the 60 or so penicillin tablets I took could have had an effect on my menstrual cycle? Has anyone had a similar experience?

Thanks.

[Candy]

no, but being sick itself can make your cycle messed up.

[tinmuning]

There are several studies which show the relationship of penicillin and amenorrhea and delayed menstrual cycle. However, since you had unprotected sex (withdrawal doesn't guarantee that you won't get pregnant), it is best to get a confirmatory pregnancy test just to be sure.