Before taking ethionamide, 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: liver disease, kidney disease, underactive thyroid (hypothyroidism), eye problems (such as optic neuritis, cataracts, diabetic retinopathy).

Alcohol may increase the risk of liver disease or mental/mood changes. Avoid alcoholic beverages while using this medication.

Ethionamide may cause live bacterial vaccines (such as typhoid vaccine) to not work well. Tell your health care professional that you are using ethionamide before having any immunizations/vaccinations.

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

If you have diabetes, this product may lower your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of low blood sugar, such as sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness, or tingling hands/feet. Your doctor may need to adjust your diabetes medication, exercise program, or diet.

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using ethionamide. Ethionamide may harm an unborn baby. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.