• you are allergic to any ingredient in Ethionamide
• you have severe liver disease.

Contact your doctor or health care provider right away if any of these apply to you.

Some medical conditions may interact with Ethionamide. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

• if you are pregnant, planning to become pregnant, or are breast-feeding
• if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
• if you have allergies to medicines, foods, or other substances
• if you have diabetes, liver problems, or vision problems.

Some medicines may interact with Ethionamide. However, no specific interactions with Ethionamide are known at this time.

Important safety information:

• Ethionamide may cause dizziness, lightheadedness, or fainting. Alcohol, hot weather, exercise, and fever can increase these effects. To prevent them, sit up or stand slowly, especially in the morning. Also, sit or lie down at the first sign of dizziness, lightheadedness, or weakness.
• Avoid drinking alcohol or taking other medications that cause drowsiness (eg, sedatives, tranquilizers) while taking Ethionamide. Ethionamide will add to the effects of alcohol and other depressants. Ask your pharmacist if you have questions about which medicines are depressants.
• Ethionamide may cause increased sensitivity to the sun. Avoid exposure to the sun, sunlamps, or tanning booths until you know how you react to Ethionamide. Use a sunscreen or wear protective clothing if you must be outside for a prolonged period.
• Ethionamide is effective only against bacteria. It is not effective for treating viral infections (eg, the common cold).
• It is important to use Ethionamide for the full course of treatment. Failure to do so may decrease the effectiveness of Ethionamide and may increase the risk that the bacteria will no longer be sensitive to Ethionamide and will not be able to be treated by this or certain other antibiotics in the future.
• You may be required to take a vitamin B supplement while taking Ethionamide.
• Diabetes patients - Ethionamide may affect your blood sugar. Check blood sugar levels closely and ask your doctor before adjusting the dose of your diabetes medicine.
• Lab tests, including blood sugar, thyroid function tests, liver function tests, and vision tests, may be performed to monitor your progress or to check for side effects. Be sure to keep all doctor and lab appointments.
• Ethionamide should not be used in children younger 12 years. Safety and effectiveness in this age group have not been confirmed. 
• Pregnancy and breast-feeding: If you become pregnant, discuss with your doctor the benefits and risks of using Ethionamide during pregnancy. It is unknown if Ethionamide is excreted in breast milk. If you are or will be breast-feeding while you are using Ethionamide, check with your doctor or pharmacist to discuss the risks to your baby.

Check with your doctor if any of these most common side effects persist or become bothersome:

Diarrhea; dizziness; drowsiness; headache; increased salivation; loss of appetite; metallic taste; mouth sores; nausea; restlessness; stomach pain; vomiting; weight loss.

Seek medical attention right away if any of these severe side effects occur:

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); change in sense of smell; depression; easy bruising or bleeding; low blood sugar (eg, increased heartbeat, headache, chills, sweating, tremor, increased hunger, changes in vision, nervousness, weakness, dizziness, drowsiness, fainting); tingling of hands or feet; vision changes (eg, loss of vision); yellowing of the skin or eyes.

 This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.