Niacin and Simvastatin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Niacin
Simvastatin
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased niacin and simvastatin exposure and an increased risk of myopathy or rhabdomyolysis
Interaction Deep Dive
Dose-related myopathy, including rhabdomyolysis, has been reported with the concomitant use of simvastatin and lipid-modifying doses of niacin (1 g/day or greater); however, people of Chinese descent are at greater risk. It is not known if the risk of myopathy seen in Chinese patients applies to other Asian patients. In pharmacokinetic interaction studies, the AUC of simvastatin and its metabolite increased by up to 40% and 60%, respectively, when simvastatin and niacin were coadministered. Avoid coadministration of simvastatin (or ezetimibe/simvastatin) with lipid-modifying doses of niacin-containing products in Chinese patients. Evaluate the benefit/risk of concomitant use in all patients12.
Why it happens (mechanism)
Unknown
Literature reports
3 reports — tap to read
a) Exposure to simvastatin and its metabolite increased by 40% and 60%, respectively, with coadministration of simvastatin and niacin in a pharmacokinetic study. Subjects received niacin extended-release 2 grams and simvastatin 20 mg as single doses. The mean ratio (with niacin/without niacin) of simvastatin was 1.4 for AUC and 1.06 for Cmax. The corresponding ratios for simvastatin acid (beta-hydroxyacid of simvastatin) were 1.6 for AUC and 1.84 for Cmax 2.
b) The incidence of myopathy was about 0.05% for non-Chinese patients (n=7367) versus 0.24% for Chinese patients (n=5468) in a clinical study in patients at high risk of cardiovascular disease who received simvastatin 40 mg/day for a mean follow-up of 3.9 years. In Chinese patients who received extended-release niacin 2 g/day with simvastatin 40 mg/day or ezetimibe 10 mg/simvastatin 40 mg/day, the incidence of myopathy was 1.24% 32.
c) In a pharmacokinetic interaction study in healthy subjects (n=13), the mean Cmax and AUC of niacin extended-release tablets (1000 mg for 2 days and 2000 mg for 5 days, following a low-fat breakfast) increased 9% and 22%, respectively, when given with ezetimibe 10 mg/simvastatin 20 mg once daily for 7 days. The mean Cmax and AUC of nicotinuric acid also increased 10% and 19%, respectively. In the same study (n=15), concurrent niacin extended-release and ezetimibe/simvastatin decreased the mean Cmax of ezetimibe (1%) and simvastatin (2%), and increased the mean Cmax of simvastatin acid (18%). The mean AUC of total ezetimibe, simvastatin, and simvastatin acid were increased by 26%, 20%, and 35%, respectively. Prior studies have not demonstrated clinically significant pharmacokinetic interactions when ezetimibe is coadministered with simvastatin alone 1.
Common questions
Can I take Niacin and Simvastatin together?
Increased niacin and simvastatin exposure and an increased risk of myopathy or rhabdomyolysis Always confirm with your pharmacist or prescriber before making any change.
How serious is the Niacin and Simvastatin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Niacin or Simvastatin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (3)
- Product Information: VYTORIN(R) oral tablets, ezetimibe simvastatin oral tablets. Organon LLC (per FDA), Jersey City, NJ, 2024. DailyMed
- Product Information: ZOCOR(R) oral tablets, simvastatin oral tablets. Organon & Co (per FDA), Jersey City, NJ, 2022. DailyMed
- Product Information: VYTORIN(R) oral tablets, ezetimibe simvastatin oral tablets. Merck Sharp & Dohme Corp (per FDA), Whitehouse Station, NJ, 2019. DailyMed
Keep reading about Niacin
Keep reading about Simvastatin
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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