Before taking diethylpropion, tell your doctor or pharmacist if you are allergic to it; or to any other sympathomimetic amines (for example, 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, glaucoma, high blood pressure, high blood pressure in the lungs (pulmonary hypertension), heart problems (such as fast/irregular heartbeat, heart valve problems, previous heart attack), kidney disease, mental/mood problems (such as anxiety, bipolar disorder, psychosis, schizophrenia), seizure, 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.

During pregnancy, this medication should be used only when clearly needed. It is not recommended for use for long periods or in high doses near the expected delivery date because of possible harm to the unborn baby. Discuss the risks and benefits with your doctor. Infants born to mothers who have been using this medication for a long time or in high doses may have withdrawal symptoms such as irritability or extreme tiredness. Tell your doctor right away if you notice any of these symptoms in your newborn.

This drug may pass into breast milk and could have undesirable effects on a nursing infant. Breastfeeding is not recommended while using this drug. Consult your doctor before breastfeeding.