Before taking atomoxetine, 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 a certain adrenal problem (pheochromocytoma), bladder or prostate problems, glaucoma, heart problems (such as irregular heartbeat, heart failure, previous heart attack, problems with heart structure), family history of heart problems (such as sudden cardiac death, irregular heartbeat), high blood pressure, liver disease, personal/family history of mental/mood disorders (such as bipolar disorder, depression, psychosis, suicidal thoughts), stroke. This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis). Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).