Found this info while researching drugs.
The following is a list of ingredients, medications, drugs, and compounds that have a high reputation for causing hair loss when taken in excess, and sometimes when taken (or experienced) in moderation. This list is by no means all-inclusive, but its a helpful start. If you feel you are experiencing hair loss due to any external factors, discuss it with your physician.
allopurinol, arsenic, apirin, l-asparaginase, bismuth, bleomycin, boric acid, bromocriptine, carbamazepine, carbon monoxide, chlorambucil, chloramphenicol, cimetidine, colchicine, clofibrate, clomiphene citrate, coumarin anticoagulant, cyclophosphamide, cyproterone acetate, dactinomycin, danazol, diethyl carbamazepine, dipyridamole, doxorubicin, ethionamide, etoposide, etretinate, fenifibrate, gentamycin sulphate, guanethidine, heparin (telogen effluvium after 6-16 weeks ), hydroxychloroquine, ibuprofen, idoxuridine, indandione, indomethacin, interferon, iodine, isophosphamide, levamisole, levodopa, lithium, mepacrine, mercury, mesalazine, methisazone, methotrexate, methyl CCNU, methysurgide, metoprolol, mitomycin, mitrexantrone, morphine, nadolol, nafoxidine, nicotinic acid, nicotinyl alcohol, nitrofurantoin sodium, norethisterone, estrogens, oral contraceptives, para aminosalicylate, phenindione, phenprocoumon, potassium thiocyanate, procainamide, propanolol, selenium sulphide, sodium aurothiomalate, sodium valproate, spironolactone, sulphasalazine, tamoxifen, thalium acetate, thiamphenicol, terfenadine, trimethadione, troxidone, vasopressin, vincristine, vindesine, vitamin A, warfarin
If you are able to determine that your medications / drugs are the cause, its important that you do not just immediately stop taking the them. Several medications can be substituted with others that may not have hair loss as a side effect, so one should always consult their physician before making any changes to their medications.