Niacin Safety & Side Effects
Our assessment
Based on the provided data, niacin from food and beverages is safe. However, dietary supplements containing 30 mg or more of nicotinic acid can cause noticeable side effects. The most common reaction is a skin flush, causing redness, burning, tingling, and itching on the face, arms, and chest FDA FAERS ↗. This flush can also be accompanied by headaches, rashes, and dizziness FDA FAERS ↗. These effects are dose-dependent and are a key safety consideration.
Safety profile
FDA data reports that niacin supplements can cause a specific set of side effects. For doses of 30 mg or more of nicotinic acid, the primary side effect is the skin flush described above FDA FAERS ↗. At higher medicinal doses of 1,000 mg or more per day, more severe side effects can occur. These include low blood pressure, which can increase the risk of falls, extreme tiredness, and high blood sugar levels FDA FAERS ↗. The provided data does not include specific adverse event report counts for each side effect.
How it works
Niacin is a B vitamin that the body uses to convert food into energy. Data not available on the exact mechanism of action for the flush effect from the provided source.
Our recommendation
Be aware that niacin supplements containing 30 mg or more of nicotinic acid can cause a skin flush, headache, rash, and dizziness FDA FAERS ↗. Individuals with low blood pressure or diabetes should be particularly cautious with high-dose niacin (1,000 mg or more daily), as it can cause low blood pressure and high blood sugar levels FDA FAERS ↗. Niacin can also interact with tuberculosis drugs such as isoniazid and pyrazinamide, which can interfere with the body's ability to produce niacin FDA FAERS ↗. Consult a healthcare provider before starting high-dose niacin supplements.
AI-assisted analysis. Data sourced from NIH ODS and FDA.
Safety Overview
The niacin that food and beverages naturally contain is safe. However, dietary supplements with 30 mg or more of nicotinic acid can make the skin on your face, arms, and chest turn red and burn, tingle, and itch. This can also lead to headaches, rashes, and dizziness. If you take nicotinic acid as a medication in doses of 1,000 or more mg/day, it can cause more severe side effects . These include: Low blood pressure (which can increase the risk of falls) Extreme tiredness High blood sugar levels Nausea , heartburn, and abdominal pain Blurred or impaired vision and fluid buildup in the eyes Long-term treatment, especially with extended-release forms of nicotinic acid, can cause liver problems, including hepatitis and liver failure. Niacin in the form of nicotinamide has fewer side effects than nicotinic acid. However, at high doses of 500 mg/day or more, nicotinamide can cause diarrhea and easy bruising and can increase bleeding from wounds. Even higher doses of 3,000 mg/day or more can cause nausea, vomiting, and liver damage. The daily upper limits for niacin from dietary supplements are listed below.
Drug Interactions
Niacin dietary supplements can interact or interfere with certain medicines that you take, and some medicines can lower niacin levels in your body. Here are some examples: Tuberculosis drugs (such as isoniazid and pyrazinamide) interfere with the body’s ability to convert tryptophan to niacin. This interference can lower niacin levels in your body. High doses of nicotinic acid (1,500 mg/day or more) can raise blood sugar levels and interfere with the effectiveness of diabetes medications. These doses can even raise blood sugar levels in people who don’t have diabetes. Tell your doctor, pharmacist , and other health care providers about any dietary supplements and prescription or over-the-counter medicines you take. They can tell you if the dietary supplements might interact with your medicines. They can also tell you if the medicines might interfere with how your body absorbs , uses, or breaks down niacin and other nutrients.