SIDE EFFECTS: Flushing of the face and neck along with warmth, headache, itching, burning, sweating, chills, or tingling may occur within 20 minutes of taking this medication. Flushing may persist for a few hours after use. These effects should improve or go away as your body adjusts to the medication. Dizziness, stomach upset, heartburn, nausea, vomiting, and diarrhea may also occur. If these effects persist or worsen, notify your doctor promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur: severe dizziness/fainting, fast/irregular heartbeat, severe headache (migraine), unusual joint pain, swelling of legs/arms, vision problems.

Tell your doctor immediately if any of these rare but very serious side effects occur: severe stomach/abdominal pain, black/tarry stools, easy bruising/bleeding, unexplained muscle pain/tenderness/weakness, persistent nausea/vomiting, change in the amount of urine, dark urine, vomit that looks like coffee grounds, yellowing eyes/skin.

A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, persistent itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the Niacor (niacin tablets) Side Effects Center for a complete guide to possible side effects »

PRECAUTIONS: Before taking niacin, 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.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: very low blood pressure, current liver disease, increase in liver enzymes, current ulcer, current bleeding.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: alcohol use, bleeding problems (e.g., low platelets), diabetes, gallbladder disease, glaucoma, gout, heart disease (e.g., recent heart attack, unstable angina), kidney disease, liver disease, untreated mineral imbalance (low phosphate levels), history of stomach/intestinal ulcers, underactive thyroid (hypothyroidism).

This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

To minimize dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. This is very important if you are also taking medication to lower your blood pressure.

Before having surgery, tell your doctor or dentist that you are taking this medication.

If you have diabetes, this drug may increase your blood sugar levels. Check your blood glucose levels regularly as directed by your doctor. Tell your doctor immediately if you have symptoms of high blood sugar such as increased thirst and urination. Your anti-diabetic medication or diet may need to be adjusted.

This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.

This medication passes into breast milk. Consult your doctor before breast-feeding.