Glucomannan - Contrave (Bupropion, Naltrexone) Interaction
Herbal: Glucomannan
Also Known As: Glucomanano, Glucomannane, Konjac, Konjac Mannan
Drug: Bupropion, Naltrexone
Brand names:
Contrave
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 25, 2025
Interaction Details
Bupropion, Naltrexone is classified as belonging to the following category: Oral Drugs
Theoretically, glucomannan may decrease absorption of drugs taken orally.
Due to its viscosity and bulking effects, there is concern that glucomannan can decrease the absorption of oral drugs. A small clinical study in healthy volunteers shows that taking glyburide 2.5 mg plus glucomannan 3.9 grams with breakfast reduces plasma levels of glyburide when compared with breakfast and glyburide alone. In addition, animal research demonstrates this effect on amoxicillin, but shows increased absorption of metronidazole. This mouse model also demonstrates that metronidazole elimination is prolonged, but amoxicillin elimination is enhanced by 38%; glucomannan may also affect the distribution of some drugs. To avoid changes in absorption, take glucomannan 30-60 minutes after taking oral drugs.
Interaction Rating
Likelihood of Occurrence
ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
References
- Shima K, Tanaka A, Ikegami H, et al. Effect of dietary fiber, glucomannan, on absorption of sulfonylurea in man. Horm Metab Res 1983;15:1-3.
- Zhang Y, Aldamarany WAS, Song G, et al. Influence of konjac glucomannan and its derivatives on the oral pharmacokinetics of antimicrobial agent in antibiotics cocktails: Keep vigilant on dietary fiber supplement. Int J Biol Macromol 2023;251:126306.
Glucomannan Overview
Glucomannan is a type of soluble fiber that comes from the konjac root, which is native to Asia. It is often used as a dietary supplement to promote weight loss and improve digestive health. When glucomannan is mixed with a liquid, it forms a gel-like substance that can help to reduce appetite by promoting a feeling of fullness. It can also help to regulate bowel movements and relieve constipation. Some studies have suggested that glucomannan may be effective for weight loss and it is a common ingredient in weight loss products, such as Lipozene.
Bupropion, Naltrexone Overview
-
The combination of naltrexone and bupropion is used along with a reduced calorie diet and exercise plan to help adults who are obese, or who are overweight and have weight-related medical problems, to lose weight and then to keep from gaining back that weight. Naltrexone is in a class of medications called opiate antagonists. Bupropion is in a class of medications called antidepressants. These medications work together on two areas of the brain, the hunger center and the reward system, to reduce appetite and help control cravings.
Glucomannan - More Interactions
Glucomannan interacts with 1987 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
Return to the main supplement interaction checker page
Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
Ask A Pharmacist About Your Herbal Questions!
Dr. Brian Staiger, PharmD
In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
Ask A Pharmacist