Reviewed on 9/23/2021

What Is Niacin and How Does It Work?

Niacin is form of vitamin B3. Niacin is also called nicotinic acid. Niacin is not stored in the body which means that you need a regular supply of niacin through vitamins and foods. Niacin helps the digestive system, skin, and nerves to function. It is also important converting food to energy.

Niacin is a used as a treatment option for low cholesterol (HDL), high cholesterol (LDL), and triglyceride levels.

Niacin is available under the following different brand names: Simcor

Dosages of Niacin


  • 50 mg - 1 gram tablet, extended release taken by mouth

Dosage Considerations

  • Take with cold liquid and a low-fat snack.
  • Swallow tablet whole; do not break, crush, or chew.
  • Flushing may be reduced by pre-treatment with no enteric-coated aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs), 30 minutes before dose.
  • Reiterate dose if therapy discontinued for over 7 days.
  • Due to risk of hepatotoxicity, substitute Simcor only for equivalent doses of niacin-ER, and no other forms of niacin.
  • Monitor liver function tests 6 weeks after initiation or dose escalation.

Adult Dosage


December 31, 2015: Manufacturer voluntarily withdrew drug from the market and discontinued distribution April 15, 2016: Based on several large cardiovascular outcome trials including AIM-HIGH, ACCORD, and HPS2-THRIVE, the FDA decided that "scientific evidence no longer supports the conclusion that a drug-induced reduction in triglyceride levels and/or increase in HDL-cholesterol levels in statin-treated patient's results in a reduction in the risk of cardiovascular events". Consistent with this conclusion, the FDA has determined that the benefits of niacin ER tablets for co-administration with statins no longer outweigh the risks, and the approval for this indication should be withdrawn.

Pediatric Dosage

Safety and efficacy has not been established.

What Are Side Effects Associated with Using Niacin?

Side effects associated with use of niacin, includes the following:

  • flushing
  • headache
  • backache
  • nausea
  • itching
  • diarrhea
  • increased levels of creatine phosphokinase
  • death of muscle fibers due to injury (rhabdomyolysis)
  • increased liver function tests

Hypersensitive reactions include one or more of the following symptoms:

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Niacin?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

  • Niacin has severe interactions with at least 32 different drugs.
  • Niacin has serious interactions with at least 79 different drugs.
  • Niacin has moderate interactions with at least 57 different drugs.
  • Niacin has minor interactions with at least 33 different drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Niacin?


This medication contains niacin. Do not take Simcor if you are allergic to niacin or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


Avoid use if hypersensitivity, active liver disease or unexplained elevated transaminases, active peptic ulcer, arterial bleeding, pregnant or lactating, Strong CYP3A4 inhibitors (itraconazole, ketoconazole, posaconazole, erythromycin, clarithromycin, telithromycin, HIV protease inhibitors, nefazodone, boceprevir, telaprevir, and cobicistat) or other drugs that may increase systemic simvastatin exposure (gemfibrozil, cyclosporine, danazol, amiodarone, verapamil, and diltiazem).

Effects of Drug Abuse

  • There are no effects of drug abuse with the use of niacin.

Short-term Effects

  • There are no short-term effects from use of niacin.

Long-term Effects

  • There are no long-term effects from use of niacin.

Pregnancy and Lactation

  • Do not take niacin when pregnant or if lactating.
Medscape. Niacin.

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