Tetracycline helps patients diagnosed with any of the numerous bacterial infections to get the symptoms under control by slowing down the growth of bacteria. It's very important that tetracycline is used only for conditions for which it has been prescribed – such as acne, genital and urinary system infections, pneumonia and a number of other ones. Taking tetracycline is associated with a number of side effects you need to be aware of. The following side effects are possible, especially at the beginning of your treatment: mild nausea, vaginal itching, trouble swallowing, sores or swelling in your rectal or genital area, stomach upset, swollen tongue, vomiting, and diarrhea. As long as the symptoms mentioned do not change in intensity and get bothersome you do not need to report them to your health care provider. However, if your mild side effects change in intensity and start to bother you too much – contact your doctor, as you may need a dose adjustment or other changes need to be made to your treatment schedule. Never give tetracycline to children younger than eight, as this drug can cause permanent teeth discoloration in them. Tetracycline must not be used by pregnant or breastfeeding women, as it has been classified as FDA pregnancy category D.