Vaginal spotting and antibiotics?

These people are wrong--vaginal bleeding CAN be one of the side effects of amoxicillin, and you should call the doctor about it. It doesn't matter whether you're taking birth control or not.

Antibiotics should have a BLACK BOX WARNING: Reduces efficacy of oral contraceptives. Always use backup method until next pack. Double barrier such as condom* and spermicidal foam or diaphram and spermicidal gel. Same is true after even minor bout of diarrhea.

*Note - Condoms, alone, and when used properly are only useful to prevent the spread of STDs. To prevent pregnancy, double barrier method is required. Condom must be worn prior to any physical contact with areas near genitalia, and removed immediately after ejaculation, penis still erect to prevent leaks and spills that cause pregnancy and disease. If more groups distributed this vital information, instead of "abstinence only" literature or photos of aborted feti, the cause would go far to prevent unwanted pregnancies and abortions no one wants.

Yes, if you are on birth control pills, this is normal because antibiotics decrease the effectiveness of the Pill. Many women on the Pill will experience breakthrough bleeding when on antibiotics. If you are on the Pill and you take antibiotics, you should use a back up barrier method, like condoms, for the entire time you are on antibiotics and for seven days after you finish them or you could become pregnant if you are sexually active during this time.

Are you on birth control pills? This can happen with them. They decrease the action of the pill so that you bleed from the change in hormones. You would also need to use a condom while you are on it.