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Do not use Cephalexin if you are allergic to it. In most cases, if you have a known allergy to Cephalexin, you probably will also be allergic to other cephalosporin antibiotics. Some of the examples of cephalosporin are cefaclor, cefadroxil, cefdinir, cefditoren, cefixime, cefprozil, ceftazidime, and cefuroxime. If you notice, cephalosporin drugs start with 'cef'. Remember this and you will be better prepared to avoid this drug. Also tell your doctor if you are allergic to penicillin or amoxicillin. You may have a higher chance of being allergic to cephalexin. You should not take Cephalexin if you have certain underlying conditions. Some medical conditions or diseases may also stop you from taking Cephalexin. These diseases may include kidney and liver disease, colitis, diabetes and malnutrition. Most of these diseases alter your body's ability to metabolize Cephalexin. For example, Cephalexin contains sugar, so you might not want to take it if you have diabetes. There have not been many studies about the effects of Cephalexin on unborn babies. Therefore, it is best to discuss alternative options with your physician if you are pregnant. Cephalexin should only be taken by pregnant women if there is no other choice. If you are taking any other drugs aside from Cephalexin, let your doctor know about it. There is a chance for drug interaction meaning taking another drug may affect the effectiveness of Cephalexin. For example, some vaccines that contain bacteria such as typhoid and BCG may be affected by Cephalexin. In addition, some studies show that Cephalexin can interfere with the effectiveness of oral contraceptives. So if you are taking Cephalexin while taking pills, you might get pregnant. Other drugs that may interact with Cephalexin are Coumadin, metformin and probenecid. Certain herbal medicines may interfere with the effectiveness of Cephalexin, so it's important to inform your doctor of any herbal medicines or supplements that you are currently taking. If you feel like there is a reason that you shouldn't take Cephalexin, it's a good idea to tell your doctor. Your doctor may either reduce the dose or switch you to a different drug entirely. Special tests, such as a skin test, can also be done to determine if you can safely take the drug.

Summary:
Tell your doctor about any allergies that you have. Make sure your doctor is aware of any underlying conditions you have. Inform your doctor if you are pregnant. Make your doctor aware of any other medications you're currently taking. Tell your doctor if you are taking any herbal medicines. Let your doctor know if you don't think Cephalexin is a good choice for you.