Before taking phendimetrazine, tell your doctor or pharmacist if you are allergic to it; or to any other sympathomimetic amines (including decongestants such as pseudoephedrine, stimulants such as amphetamine, appetite suppressants such as phentermine); 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: diabetes, high blood pressure, glaucoma, heart problems (such as chest pain, heart attack, heart murmur, fast/irregular heartbeat, heart valve problems), mental/mood problems (such as severe anxiety/agitation, depression, psychosis, schizophrenia), high blood pressure in the lungs (pulmonary hypertension), kidney disease, seizure problem, stroke, overactive thyroid (hyperthyroidism), personal or family history of a substance use disorder (such as overuse of or addiction to drugs/alcohol).

This drug may make you dizzy or blur your vision. It may also rarely make you drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

If you have diabetes, check your blood sugar regularly as directed and share the results with your doctor. Your doctor may need to adjust your diabetes medication during treatment with this drug.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be at greater risk for dizziness and high blood pressure while using this drug.

This medication must not be used during pregnancy. Weight loss offers no potential benefit to a pregnant woman and may harm an unborn baby. If you become pregnant or think you may be pregnant, tell your doctor right away.

It is unknown if this drug passes into breast milk. However, similar drugs pass into breast milk. Breastfeeding is not recommended while using this drug. Consult your doctor before breastfeeding.