Drug interactions
Metformin + Niacin
Severity: Moderate
Metformin and Niacin: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Niacin can raise blood glucose and may counteract the glucose-lowering effect of metformin, worsening diabetes control.
What this interaction means in plain words
Metformin and Niacin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Metformin belongs to Endocrine; Niacin belongs to Cardiovascular.
Why it happens
Niacin induces insulin resistance and hyperglycemia, opposing metformin's effect.
What to do
Monitor blood glucose and HbA1c when niacin is started or its dose changed. Adjust the metformin dose or add therapy if control worsens.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Niacin
- Alogliptin-metformin + Niacin Moderate
- Atorvastatin + Niacin Moderate
- Canagliflozin-metformin + Niacin Moderate
- Cholestyramine + Niacin Moderate
- Colestipol + Niacin Moderate
- Dapagliflozin-metformin + Niacin Moderate
Other interactions of Metformin
Frequently asked questions
Can I take Metformin with Niacin?
MediHelp rates the interaction as moderate. Metformin and Niacin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Niacin can raise blood glucose and may counteract the glucose-lowering effect of metformin, worsening diabetes control.
How serious is the interaction between Metformin and Niacin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood glucose and HbA1c when niacin is started or its dose changed. Adjust the metformin dose or add therapy if control worsens.
What other medicines interact with Niacin?
MediHelp also lists interactions of Niacin with, for example, Alogliptin-metformin, Atorvastatin, Canagliflozin-metformin. The full list is on the Niacin page.
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