Niacin Side Effects

Medically reviewed by Drugs.com. Last updated on Jul 16, 2024.

Applies to niacin: oral capsule, oral capsule extended release, oral tablet, oral tablet extended release.

Precautions

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly to lower your cholesterol and triglycerides and if you should continue to take it. Blood and urine tests may be needed to check for unwanted effects.

Check with your doctor right away if you have dark-colored urine, diarrhea, a fever, muscle cramps or spasms, muscle pain or stiffness, or feel very tired or weak. These could be symptoms of a serious muscle problem called rhabdomyolysis, which can cause kidney problems.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

This medicine may affect blood sugar levels. If you notice a change in the results of your blood or urine sugar tests or if you have any questions, check with your doctor.

This medicine may cause you to feel dizzy or faint, especially when you get up from a lying or sitting position. Getting up slowly may help. This effect should lessen after a week or two as your body gets used to the medicine. However, if the problem continues or gets worse, check with your doctor.

Do not stop taking niacin without first checking with your doctor. When you Stop taking niacin, your blood cholesterol levels may increase again. Your doctor may want you to follow a special diet to help prevent this from happening.

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine.

Do not take vitamins or other dietary supplements unless they have been discussed with your doctor. This especially includes vitamins or dietary supplements that contain niacin or similar ingredients.

Serious side effects of niacin

Along with its needed effects, niacin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking niacin:

Other side effects of niacin

Some side effects of niacin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For healthcare professionals

Applies to niacin: compounding powder, oral capsule, oral capsule extended release, oral liquid, oral tablet, oral tablet extended release.

Cardiovascular adverse events

• Very common (10% or more): Flushing (i.e., warmth, redness, itching, and/or tingling) (up to 88%)
• Frequency not reported: Tachycardia, palpitations, atrial fibrillation, other cardiac arrhythmias, syncope, hypotension, postural hypotension^[Ref]

Dermatologic

• Common (1% to 10%): Rash, pruritus
• Frequency not reported: Sweating, skin burning sensation, maculopapular rash, dry skin
• Postmarketing reports: Skin discoloration^[Ref]

Gastrointestinal

• Very common (10% or more): Diarrhea (up to 14%), nausea (up to 11%)
• Common (1% to 10%): Vomiting
• Frequency not reported: Peptic ulcers, eructation, flatulence^[Ref]

Hematologic

• Postmarketing reports: Slight reductions in platelet counts, prothrombin time prolonged^[Ref]

Hypersensitivity

• Postmarketing reports: Hypersensitivity reactions (e.g., anaphylaxis, angioedema, urticaria, flushing, dyspnea, tongue edema, larynx edema, face edema, peripheral edema, laryngismus, vesiculobullous rash)^[Ref]

Hepatic

• Postmarketing reports: Hepatitis, jaundice^[Ref]

Metabolic

• Frequency not reported: Decreased glucose tolerance, gout^[Ref]

Musculoskeletal

• Frequency not reported: Myalgia, myopathy^[Ref]

Nervous system

• Frequency not reported: Dizziness, syncope
• Postmarketing reports: Migraine, asthenia, paresthesia^[Ref]

Ocular

• Postmarketing reports: Blurred vision, macular edema^[Ref]

Psychiatric

• Postmarketing reports: Insomnia, nervousness^[Ref]

Other

• Frequency not reported: Chills, edema^[Ref]

Respiratory

• Common (1% to 10%): Cough increased
• Frequency not reported: Dyspnea^[Ref]

See also:

Frequently asked questions

• How long does niacin stay in the human system?

Further information

Niacin side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer