Before taking it, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: blood clots (e.g., deep vein thrombosis, pulmonary embolism, stroke), high cholesterol/triglycerides, limited or no ability to walk (immobility), diabetes, high blood pressure, smoking, cataracts, liver disease. If you have breast cancer that has spread to other parts of the body, you may experience increased bone/cancer pain and/or disease flare-up as you start taking tamoxifen. In some cases, this may be a sign of a good response to the medication. Symptoms include increased bone pain, increased tumor size, or even new tumors. These symptoms usually disappear quickly. In any case, report these symptoms right away to your doctor. Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day. Ask your pharmacist or healthcare provider before using any medicine.