Do not use leflunomide if you are pregnant, and stop taking  leflunomide if you think you might be pregnant. Use birth control to prevent pregnancy while you are taking leflunomide, and until you complete a "drug elimination" procedure.
Leflunomide can cause severe or fatal liver damage. Tell your doctor if you have a history of liver disease or if you also use other medicines such as: pain or arthritis medicine (including aspirin, Tylenol, and Advil/Motrin), medicines to treat tuberculosis or other infections, seizure medication, hormonal birth control or hormone replacement therapy, chemotherapy, cholesterol-lowering medicine, heart medication, or blood pressure medicine.
Your liver function will need to be tested often, and you may need to stop taking leflunomide based on the results of these tests.
Before taking this medicine
You should not use this medicine if you are allergic to leflunomide or teriflunomide, or if:
you are pregnant (you will need to have a negative pregnancy test before starting this treatment);
you have severe liver disease; or
you are also using teriflunomide.
Do not use leflunomide if you are pregnant or may become pregnant. Avoid getting pregnant until after you stop taking leflunomide and undergo a "drug elimination" procedure to help rid your body of this medicine. Stop taking leflunomide and call your doctor right away if you miss a period or think you might be pregnant.
To make sure leflunomide is safe for you, tell your doctor if you have:
a history of liver disease or hepatitis (leflunomide can cause severe liver problems);
a severe or uncontrolled infection;
kidney disease;
nerve problems, such as neuropathy caused by diabetes;
a history of tuberculosis;
a weak immune system or bone marrow disorder; or
if you are using any drugs that weaken your immune system (such as cancer medicine or steroids).
Use birth control to prevent pregnancy while you are taking this medicine. After you stop taking leflunomide, continue using birth control until you have received blood tests to make sure the drug has been eliminated from your body.
Ask your doctor if you should use a barrier form of birth control (condom or diaphragm with spermicide). Using hormonal contraception (birth control pills, injections, implants, skin patches, and vaginal rings) may increase your risk of liver damage while taking leflunomide.
It is not known whether leflunomide passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.
How should I take leflunomide?
Before you start treatment with leflunomide, your doctor may perform tests to make sure you do not have tuberculosis or other infections.
Follow all directions on your prescription label. Your doctor may occasionally change your dose. Do not use  leflunomide in larger or smaller amounts or for longer than recommended.
Your blood pressure will need to be checked often.
Leflunomide can lower blood cells that help your body fight infections and help your blood to clot. Your blood will need to be tested often. Your leflunomide treatment may be stopped for a short time based on the results of these tests.
Your liver function will also need to be tested often, and you may need to stop taking leflunomide based on the results of these tests.
After you stop taking leflunomide, you may need to be treated with other medicines to help your body eliminate leflunomide quickly. If you do not undergo this drug elimination procedure, leflunomide could stay in your body for up to 2 years. Follow your doctor's instructions.
You will also need to go through this drug elimination procedure if you plan to become pregnant after you stop taking leflunomide.
Arthritis is often treated with a combination of drugs. Use all medications as directed by your doctor. Read the medication guide or patient instructions provided with each medication. Do not change your doses or medication schedule without your doctor's advice.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include diarrhea, stomach pain, pale skin, easy bruising or bleeding, dark urine, or jaundice (yellowing of the skin or eyes).
