Phentermine, Topiramate & Nutrient Depletion
Also searched as Qsymia. What the clinical evidence reports, what it may mean, and what to discuss with your pharmacist.
Phentermine, Topiramate has been associated with depletion of VITAMIN K. This does not mean a deficiency will occur — it means these are worth knowing about and, if you take Phentermine, Topiramate long-term, worth raising with your pharmacist or healthcare provider.
Take more than one medication? Open the checker with Phentermine, Topiramate pre-loaded and add the rest to see overlapping nutrient signals.
Reported nutrient depletions with Phentermine, Topiramate
Each record below is shown as published in our licensed clinical database, with its evidence rating and citations. Expand a section for food sources and talking points.
VITAMIN K
Insignificant DepletionANTICONVULSANTS
When taken during pregnancy, anticonvulsants that induce hepatic enzymes (e.g., phenobarbital, phenytoin, carbamazepine) can reduce vitamin K levels in the fetus and increase the risk of intracranial hemorrhage soon after birth. It's thought that liver enzyme induction by these drugs increases vitamin K metabolism. This has a significant effect on vitamin K levels in infants, who haven't built up stores of the vitamin. When anticonvulsants are needed during pregnancy, vitamin K 10-20 mg daily should be taken orally for the last month of pregnancy, and the baby should receive vitamin K immediately after delivery. There is also limited evidence that chronic carbamazepine or phenytoin therapy can cause subclinical reductions in vitamin K activity in adults. There are rare reports of prolonged clotting times and bleeding in people with additional risk factors for vitamin K deficiency, such as poor nutritional intake. These anticonvulsants don't significantly affect vitamin K and clotting parameters in most children and adults. For information on foods that are rich in vitamin K, see our chart.
Vitamin K is something your body needs to help blood clot properly and keep bones healthy. Topiramate is an anticonvulsant, and some drugs in that class are known to speed up liver enzymes that break down vitamin K faster than usual. That said, this interaction is rated insignificant, meaning for most adults taking this combination it is not a practical concern. If you have questions about your nutritional status or take other medications that affect clotting, a quick conversation with your pharmacist is always a reasonable idea.
What Vitamin K does & food sources
Vitamin K is required for normal blood clotting and contributes to bone health.
Common food sources:
- Leafy green vegetables (spinach, kale, broccoli)
- Vegetable oils
- Fermented foods like natto
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
If you take warfarin, vitamin K intake is a central part of your therapy — consistency matters more than avoidance. Discuss any planned change in vitamin K intake (diet or supplements) with the clinic that manages your INR.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
Never start or stop a vitamin K supplement on your own if you take warfarin — it directly changes how the medication works.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: Vitamin K interacts with warfarin: keep intake consistent and involve your anticoagulation clinic in any change.
Learn more about this nutrient: Vitamin K — uses, safety & interactions
References (8)
- Cornelissen M, Steegers-Theunissen R, Kollee L, et al. Increased incidence of neonatal vitamin K deficiency resulting from maternal anticonvulsant therapy. Am J Obstet Gynecol 1993;168:923-8. PubMed
- Cornelissen M, Steegers-Theunissen R, Kollee L, et al. Supplementation of vitamin K in pregnant women receiving anticonvulsant therapy prevents neonatal vitamin K deficiency. Am J Obstet Gynecol 1993;168:884-8. PubMed
- Renzulli P, Tuchschmid P, Eich G, et al. Early vitamin K deficiency bleeding after maternal phenobarbital intake: management of massive intracranial haemorrhage by minimal surgical intervention. Eur J Pediatr 1998;157:663-5. PubMed
- Bleyer WA, Skinner AL. Fatal neonatal hemorrhage after maternal anticonvulsant therapy. JAMA 1976;235:626-7. DOI
- Thorp JA, Gaston L, Caspers DR, Pal ML. Current concepts and controversies in the use of vitamin K. Drugs 1995;49:376-87. PubMed
- Davies VA, Rothberg AD, Argent AC, Atkinson PM, Staub H, Pienaar NL. Precursor prothrombin status in patients receiving anticonvulsant drugs. Lancet 1985;1:126-8. PubMed
- Keith DA, Gundberg CM, Japour A, et al. Vitamin K-dependent proteins and anticonvulsant medication. Clin Pharmacol Ther 1983;34:529-32. PubMed
- Tam DA Jr, Myer EC. Vitamin K-dependent coagulopathy in a child receiving anticonvulsant therapy. J Child Neurol 1996;11:244-6. PubMed
This tool is educational and is not a substitute for professional medical advice. An association is not a diagnosis and does not mean a deficiency will occur. Always talk to your pharmacist or healthcare provider before starting, stopping, or changing any medication or supplement.
Disclaimer: This checker finds which nutrients might be depleted by prescription or over-the-counter medications. Each nutrient depletion issue is rated based on clinical significance. Use your own professional judgment prior to making clinical decisions.© 2026 Therapeutic Research Center Licensed records refresh weekly · last updated July 3, 2026.
More about Phentermine, Topiramate
What drug-induced nutrient depletion means
Some medications can, over time, lower the levels of certain vitamins, minerals, or other nutrients — through reduced absorption, increased loss, or changes in how the body uses them.
Association is not deficiency
An entry here means a depletion has been reported or studied — not that it happens to everyone, or that you are deficient. Dose, duration, diet, and your own health all matter.
Evidence varies by pair
Some drug–nutrient links (like metformin and vitamin B12) are well studied; others rest on limited or preliminary research. Each entry shows the evidence rating from our licensed clinical database.
When to ask about labs
If you take an associated medication long-term, ask your healthcare provider whether monitoring is appropriate for you. Not everyone needs testing — your provider can weigh your dose, duration, and symptoms.
Don't self-supplement blindly
Supplements are not risk-free: some can interact with medications, and some (like potassium or magnesium) can be risky with kidney disease. Talk to your pharmacist before adding anything.
Never stop a medication over this
These medications are prescribed for good reasons, and the benefit usually far outweighs a manageable nutrient consideration. Any change belongs in a conversation with your prescriber.
Food first, usually
For many nutrients, a varied diet covers the gap. Each entry lists common food sources; a supplement is a decision to make with your pharmacist or provider, not a default.
Phentermine, Topiramate & nutrients: FAQs
Does Phentermine, Topiramate deplete VITAMIN K?
Should I take a supplement because I take Phentermine, Topiramate?
Should I stop taking Phentermine, Topiramate?
Where does this information come from?
Questions about Phentermine, Topiramate and your nutrition?
Ask a licensed pharmacist — free, no appointment needed.
Sources & How We Checked
Nutrient depletion records for Phentermine, Topiramate are evidence-graded and sourced from the Natural Medicines database, and are displayed as published with their citations.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference for drug-induced nutrient depletions, supplements, and interactions — the basis for this page.
- MedlinePlus, U.S. National Library of Medicine — NIH consumer drug information, used for medication overviews across the site.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.