Doxycycline is a popular prescription tetracycline antibiotic used for the treatment of infections that have been caused by the presence of bacteria in the body. This medicine is supposed to be used for as long as recommended to make sure it's efficient. If you discontinue the treatment for no obvious reason, the growth and multiplication of bacteria may resume - as a result a relapse of infection is possible. Always make sure you take this medicine for as long as recommended, and if you happened to miss a dose - take it as soon as you remembered. If you remembered too late and it is almost time for the next dose - you can skip the one you missed and carry on with the treatment. It's not recommended to skip doses too often, as this may affect the success of your treatment. How many times a day you will be required to take this medicine will depend on the kind of condition you are being treated for, as well as a number of individual factors. The drugs you are taking at the moment, your current health condition and any conditions you have ever been diagnosed with - all these factors can be important. In case you have liver or kidney disease, for instance, your health care provider will need to adjust your dose, try some additional tests, of your progress will be monitored carefully to make sure you are benefitting from the treatment without suffering from any side effects that are serious. Make sure you tell your health care provider if you are currently using any of these medications: isotretinoin, minerals, cholestyramine, penicillin antibiotics, blood thinners, colestipol, magnesium, tretinoin, zinc, calcium, drugs containing bismuth subsalicylate, vitamin and mineral supplements, or iron supplements. Children younger than 8 are never supposed to be taking this medication, as it is likely to cause permanent yellowing or graying of the teeth. It can also slow down the child's growth. This drug is also not supposed to be taken by pregnant or breastfeeding women, as it is likely to cause birth defects in unborn and nursing babies. If you think you may have got pregnant while taking this drug - report this to your health care provider as soon as possible. You will need to use reliable methods of birth control to prevent a pregnancy. It's important to know that doxycycline has been reported to affect the efficiency of hormonal birth control pills. Therefore, it's advised to talk to your doctor about contraception methods that would be efficient in your particular case.