DRUG INTERACTIONS: See also the How to Use section. Your healthcare professionals (e.g., doctor or pharmacist) may already be aware of any possible drug interactions and may be monitoring you for it. Do not start, stop or change the dosage of any medicine before checking with them first. Avoid taking MAO inhibitors (e.g., furazolidone, isocarboxazid, linezolid, moclobemide, phenelzine, procarbazine, selegiline, tranylcypromine) within 2 weeks before or after treatment with this medication. In some cases a serious, possibly fatal, drug interaction may occur. This drug should not be used with the following medications because very serious interactions may occur: delavirdine, nefazodone, telithromycin, voriconazole. Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: other anti-seizure medications (e.g., felbamate, valproic acid), lithium, SSRI antidepressants (e.g., fluoxetine), tramadol, drugs affecting liver enzymes that remove carbamazepine from your body (such as azole antifungals-including itraconazole, macrolide antibiotics-including erythromycin, cimetidine, rifamycins-including rifabutin, St John's wort, propoxyphene, danazol, calcium channel blockers-including verapamil). Carbamazepine can cause certain liver enzymes to speed up the removal of other drugs from your body, possibly decreasing their effectiveness. These affected drugs include: caspofungin, cyclosporine, doxycycline, HIV protease inhibitors (e.g., amprenavir, saquinavir), levothyroxine, psychiatric medications (e.g., clozapine, haloperidol, risperidone), theophylline, warfarin. This medication may decrease the effectiveness of birth control products that contain hormones including combination type birth control pills, patches, injections, and implants. This can result in pregnancy. You may need to use an additional form of reliable birth control while using this medication. Consult your doctor or pharmacist for details. Tell your doctor or pharmacist if you also take drugs that cause drowsiness such as: certain antihistamines (e.g., diphenhydramine), anti-anxiety drugs (e.g., diazepam), medicine for sleep (e.g., sedatives), muscle relaxants, narcotic pain relievers (e.g., codeine), psychiatric medicines (e.g., phenothiazines such as chlorpromazine, tricyclic antidepressants such as amitriptyline), tranquilizers. Check the labels on all your medicines (e.g., cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about the safe use of those products. This product can affect the results of certain lab tests (e.g., thyroid function, some pregnancy tests). Make sure laboratory personnel and your doctors know you are using this drug.