Acarbose and Phenelzine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Phenelzine
Acarbose
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.
You've been prescribed phenelzine (Nardil), an older antidepressant called an MAOI, along with acarbose (Precose), which helps control your blood sugar. When these are taken together, your blood sugar can drop lower than expected. That's because MAOIs like phenelzine can push blood sugar down on their own, adding to what your diabetes medicine already does.
Signs of low blood sugar include shakiness, sweating, dizziness, confusion, or feeling suddenly hungry. The good news is this is manageable. Keep taking both as prescribed, check your blood sugar as directed, and let your care team know how you're doing so they can fine-tune your doses if needed.
Effect: Additive hypoglycemia when phenelzine (MAOI) is combined with acarbose.
Mechanism: Unknown/uncertain; MAOIs may promote hyperinsulinemia in type 2 patients retaining insulin secretory capacity, enhancing the glucose-lowering effect. This is a pharmacodynamic (additive) interaction, not a metabolic one; neither agent is a prodrug affected here.
Onset: Rapid. Evidence: Probable. Severity: Moderate.
- Monitor blood glucose closely when phenelzine is initiated or discontinued.
- Lower doses of acarbose (or the hypoglycemic regimen) may be required and should be individualized.
- In some cases discontinuation of one agent may be warranted.
What happens
An increased risk of hypoglycemia
Interaction Deep Dive
When certain MAOIs are used alongside hypoglycemic agents, the blood glucose lowering action of those agents may be enhanced 23. In patients with type 2 diabetes who retain the ability to secrete insulin, MAOIs can produce hyperinsulinemia 7. Blood glucose should be watched carefully whenever an MAOI is started or stopped in someone already taking a hypoglycemic agent. It may be necessary to reduce the dose of insulin or of oral hypoglycemic agents 12, or alternatively to discontinue one of the two interacting drugs 4.
Why it happens (mechanism)
Unknown
How to manage this interaction
This interaction is manageable with attention from your care team.
- Keep taking both phenelzine and acarbose exactly as prescribed unless your doctor tells you otherwise.
- Monitor closely: your team will likely watch your blood sugar more carefully, especially right after starting or stopping phenelzine.
- Dose tailoring: your acarbose or other diabetes medicine dose may need to be adjusted and individualized by your care team.
- Know the warning signs of low blood sugar (shakiness, sweating, confusion) and treat as advised.
Raise any low-sugar episodes with your pharmacist or prescriber so they can adjust your plan.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Drugs classified as MAOIs may potentiate the blood glucose lowering action of hypoglycemic agents. The suggested mechanism involved MAOI interference with the homeostatic adrenergic response to hypoglycemia 5, although this mechanism was not verified 6. MAOIs seem to produce hyperinsulinemia 7.
b) Administration of selegiline (a selective MAO-B inhibitor) resulted in severe hypoglycemia in a 70-year-old man who had Parkinson's disease. This hypoglycemia occurred together with hyperinsulinemia and continued for one week following discontinuation of selegiline 8.
Common questions
Can I take Acarbose and Phenelzine together?
Combining phenelzine with acarbose can add up to a greater risk of low blood sugar, so monitor your glucose closely, especially when starting or stopping the antidepressant, and let your care team adjust your diabetes doses as needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acarbose and Phenelzine interaction?
It is rated moderate. Can be significant — usually manageable with 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 is the Acarbose and Phenelzine interaction managed?
This interaction is manageable with attention from your care team. Keep taking both phenelzine and acarbose exactly as prescribed unless your doctor tells you otherwise. Monitor closely: your team will likely watch your blood sugar more carefully, especially right after starting or stopping phenelzine. Dose tailoring: your acarbose or other diabetes medicine dose may need to be adjusted and indivi… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Acarbose or Phenelzine 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 anything you'd monitor while I'm on both?
References (8)
- Product Information: TOUJEO(R) subcutaneous injection, insulin glargine subcutaneous injection. sanofi-aventis (per manufacturer), Bridgewater, NJ, 2015. DailyMed
- Product Information: AMARYL(R) oral tablets, glimepiride oral tablets. Sanofi-Aventis U.S. LLC (per FDA), Bridgewater, NJ, 2013. DailyMed
- Product Information: Starlix(R) oral tablets, nateglinide oral tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2011. DailyMed
- Product Information: ZYVOX(R) intravenous injection, oral tablets suspension, linezolid intravenous injection, oral tablets suspension. Pfizer Inc. (per FDA), New York, NY, 2013. DailyMed
- Cooper AJ & Ashcroft G: Modification of insulin and sulfonylurea hypoglycemia by monoamine-oxidase inhibitor drugs. Diabetes 1967; 16:272-274. PubMed
- Adnitt PI: Hypoglycemic action of monoamineoxidase inhibitors (MAOI'S). Diabetes 1968; 17:628-633. PubMed
- Bressler R, Vargas-Cord M, & Lebovitz HE: Tranylcypromine: a potent insulin secretagogue and hypoglycemic agent. Diabetes 1968; 17:617-624. PubMed
- Rowland MJ, Bransome ED Jr. & Hendry LB: Hypoglycemia caused by selegiline, an antiparkinsonian drug: can such side effects be predicted?. J Clin Pharmacol 1994; 34:80-85. DOI
Keep reading about Phenelzine
Keep reading about Acarbose
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist