Drug & supplement interaction

D-mannose + Gabapentin

Gabapentin brand names: Neurontin, Gralise.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between D-mannose and Gabapentin in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

D-mannose and Gabapentin

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Gabapentin and D-mannose in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for D-mannose at all — not against Gabapentin, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

D-mannose safety at a glance

D-mannose overall Use caution Generally well tolerated short-term, but high-quality long-term safety data are limited.
Pregnancy Use caution Not enough reliable safety data, so it is best to avoid unless your doctor advises otherwise.
Breastfeeding Use caution Safety while breastfeeding is not well studied, so caution is advised.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Gabapentin and D-mannose? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests D-mannose and Gabapentin May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Diarrhea / Nausea reported in 6.3% of FDA reports for Gabapentin Additional detail

    D-mannose

    “Orally, D-mannose can cause loose stools, diarrhea, abdominal bloating, and nausea. In children, loose stools and abdominal bloating have been reported at D-mannose doses ranging from 100 mg/kg three times daily to 150 mg/kg five times daily. Diarrhea has been reported in adults taking D-mannose 2 grams daily for 6 months.”

    D-mannose · Natural Medicines adverse-effect record, reported in diarrhea.

    6 sources cited
    1. 13344. Westphal V, Kjaergaard S, Davis JA, et al. Genetic and metabolic analysis of the first adult with congenital disorder of glycosylation type Ib: long-term outcome and effects of mannose supplementation. Mol Genet Metab 2001;73:77-85. PubMed
    2. 91141. Kranjcec B, Papes D, Altarac S. D-mannose powder for prophylaxis of recurrent urinary tract infections in women: a randomized clinical trial. World J Urol. 2014 Feb;32(1):79-84.
    3. 100979. Harms HK, Zimmer KP, Kurnik K, Bertele-Harms RM, Weidinger S, Reiter K. Oral mannose therapy persistently corrects the severe clinical symptoms and biochemical abnormalities of phosphomannose isomerase deficiency. Acta Paediatr. 2002;91(10):1065-72. DOI
    4. 100981. . Damen G, de Klerk H, Huijmans J, den Hollander J, Sinaasappel M. Gastrointestinal and other clinical manifestations in 17 children with congenital disorders of glycosylation type Ia, Ib, and Ic. J Pediatr Gastroenterol Nutr. 2004;38(3):282-7. DOI
    5. 104209. Lenger SM, Bradley MS, Thomas DA, Bertolet MH, Lowder JL, Sutcliffe S. D-mannose vs other agents for recurrent urinary tract infection prevention in adult women: a systematic review and meta-analysis. Am J Obstet Gynecol. 2020;223(2):265.e1-265.e13. PubMed
    6. 100977. de Lonlay P, Seta N. The clinical spectrum of phosphomannose isomerase deficiency, with an evaluation of mannose treatment for CDG-Ib. Biochim Biophys Acta. 2009;1792(9):841-3. PubMed

    Gabapentin

    Listed in the ADVERSE REACTIONS section of the FDA label for Gabapentin, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for D-mannose but not commonly for Gabapentin: bloating or gas.

Effects for Gabapentin come from the ADVERSE REACTIONS section of its FDA label; effects for D-mannose come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 361,481 voluntary FDA FAERS reports for Gabapentin that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

From our Q&A

Questions About D-mannose or Gabapentin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers D-mannose or Gabapentin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Gabapentin

This page covers D-mannose only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Gabapentin page lists 106 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Kava (major).

By severity: 7 major · 82 moderate · 17 minor.

From our pharmacist’s overview on the Gabapentin page

“Gabapentin (Neurontin, Gralise) calms overactive nerves, which means it already slows your nervous system down, and that is exactly what 78 of the 106 supplements on this list also do. So the dominant risk here is sedation stacked on sedation, extra drowsiness at best and dangerously slowed breathing at worst, and with seven entries ra…”

Reviewed by 2 · Jul 18, 2026

Open the Gabapentin interaction page

How much people look this up

Where D-mannose and Gabapentin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement D-mannose
Top half

#538 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Gabapentin
Top 5%

#42 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every D-mannose reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The D-mannose and Gabapentin records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About D-mannose

What is D-mannose?

D-mannose
  • Preventing urinary tract infections (UTIs)
  • Treating mild UTIs
  • Urinary tract health
  • Carbohydrate-deficient glycoprotein syndrome (a rare genetic condition)

D-mannose is a natural sugar most often used to help prevent urinary tract infections, especially those caused by E. coli. Early research is promising for prevention, but the evidence is still limited and it should not replace antibiotics for an active infection. Talk to your pharmacist or doctor before using it, particularly if you are pregnant, breastfeeding, or have diabetes.

Simple sugar (monosaccharide) derived from plants such as cranberries, apples, and other fruits and vegetables · Capsules, tablets, powder; often combined with cranberry

An interaction check asks whether these two react with each other — it does not ask whether D-mannose is a good idea for someone in your situation. Here is what our D-mannose record says about it on its own.

D-mannose: dosing

There is no official, standardized dose of D-mannose, and the amounts used in research have varied. Do not use D-mannose in place of prescribed antibiotics for an active infection.

From our D-mannose monograph — the full record covers uses, side effects and every documented interaction.

Read the full D-mannose monograph & all interactions
Medication

About Gabapentin

What Is Gabapentin Used For?

Brand names: Neurontin, Gralise

Gabapentin (brands include Neurontin, Relgaabi, Gabarone, Gralise, and Horizant) is primarily used to manage postherpetic neuralgia (PHN) — the nerve pain that lingers after a shingles outbreak — in adults. Neurontin, Relgaabi, Gabarone, and gabapentin capsules, tablets, and oral solution are also used as add-on therapy for partial onset seizures (a type of epilepsy) in adults and children aged 3 and older.

Horizant (gabapentin enacarbil extended-release tablet) has two specific approvals: treatment of moderate-to-severe primary restless legs syndrome (RLS) in adults, and management of postherpetic neuralgia in adults. Horizant is not recommended for people who need to sleep during the day and stay awake at night. Gralise is approved only for postherpetic neuralgia and cannot be substituted for other gabapentin products due to its different release profile.

Most-Reported Side Effects for Gabapentin

From FAERS, the FDA’s public side-effect reporting system (361,481 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 24,972 reports
Nausea 22,728 reports
Diarrhea 18,114 reports
Headache 17,897 reports
Dizziness 16,238 reports
See full Gabapentin drug information
Keep checking

Other Drugs & D-mannose

Browse every other medication we’ve checked against D-mannose — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

We also checked D-mannose against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full D-mannose list.

See the full D-mannose interactions page
See every supplement checked against Gabapentin, ranked by severity
Evidence & sources

D-mannose References

The 6 references that drive our D-mannose monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Westphal V, Kjaergaard S, Davis JA, et al. Genetic and metabolic analysis of the first adult with congenital disorder of glycosylation type Ib: long-term outcome and effects of mannose supplementation. Mol Genet Metab 2001;73:77-85. PubMed
  2. Kranjcec B, Papes D, Altarac S. D-mannose powder for prophylaxis of recurrent urinary tract infections in women: a randomized clinical trial. World J Urol. 2014 Feb;32(1):79-84.
  3. de Lonlay P, Seta N. The clinical spectrum of phosphomannose isomerase deficiency, with an evaluation of mannose treatment for CDG-Ib. Biochim Biophys Acta. 2009;1792(9):841-3. PubMed
  4. Harms HK, Zimmer KP, Kurnik K, Bertele-Harms RM, Weidinger S, Reiter K. Oral mannose therapy persistently corrects the severe clinical symptoms and biochemical abnormalities of phosphomannose isomerase deficiency. Acta Paediatr. 2002;91(10):1065-72. DOI
  5. . Damen G, de Klerk H, Huijmans J, den Hollander J, Sinaasappel M. Gastrointestinal and other clinical manifestations in 17 children with congenital disorders of glycosylation type Ia, Ib, and Ic. J Pediatr Gastroenterol Nutr. 2004;38(3):282-7. DOI
  6. Lenger SM, Bradley MS, Thomas DA, Bertolet MH, Lowder JL, Sutcliffe S. D-mannose vs other agents for recurrent urinary tract infection prevention in adult women: a systematic review and meta-analysis. Am J Obstet Gynecol. 2020;223(2):265.e1-265.e13. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking D-mannose and Gabapentin Together: Common Questions

Is it safe to take D-mannose with Gabapentin?
We do not list a known interaction between D-mannose and Gabapentin. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do D-mannose and Gabapentin have any of the same side effects?
Yes — our sources link each of them separately to 2 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Does Gabapentin interact with any supplements?
Yes. Gabapentin has documented interactions with 106 supplements in our database — D-mannose is not one of them. The Gabapentin interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

D-mannose monograph Uses, safety profile, and every drug interaction in one place Gabapentin drug information The full plain-English guide to this medication Gabapentin supplement interactions Every supplement checked against Gabapentin, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 6 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Gabapentin and D-mannose?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.