Drug & supplement interaction

L-carnitine + Phentermine, Topiramate

Phentermine, Topiramate brand name: Qsymia.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between L-carnitine and Phentermine, Topiramate 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

L-carnitine and Phentermine, Topiramate

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 Phentermine, Topiramate and L-carnitine 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.

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.

L-carnitine safety at a glance

L-carnitine overall Use caution Generally well tolerated at typical doses, but high doses can cause stomach upset and a fishy body odor.

Pregnancy Use caution Not enough reliable safety data; use only under medical supervision.

Breastfeeding Possibly Safe When used orally. Supplemental doses of L-carnitine have been given to infants in breast milk and formula with no reported adverse effects. The effects of large... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Phentermine, Topiramate and L-carnitine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Phentermine, Topiramate

Interactions in our licensed database are recorded against drug classes, not just single drug names. Phentermine, Topiramate is filed under 6 classifications — including anticonvulsants, cytochrome p450 2c19 (cyp2c19) inhibitors, cns depressants. L-carnitine has documented interactions with 3 drug classes — the most serious being acenocoumarol (sintrom) (moderate), thyroid hormone (moderate) and warfarin (coumadin) (moderate) — and none of Phentermine, Topiramate’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

L-carnitine Does Interact With Other Medications

L-carnitine has 19 moderate known drug interactions in our database — Phentermine, Topiramate isn’t one of them. If you take anything else, check it against the full list below.

Moderate 19 No known interaction 2,811 (incl. Phentermine, Topiramate)

Taking anything else?

Check Another of Your Medications Against L-carnitine

Covers the 2,830 medications we’ve checked against L-carnitine. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests L-carnitine and Phentermine, Topiramate 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. 2 of them are worth acting on rather than waiting out — marked below.

Seizures Worth acting on Additional detail
L-carnitine
“Orally or intravenously, L-carnitine has been associated with seizures. Orally, use of L-carnitine in clinical trials has resulted in headache, although this event is rare. L-carnitine may also cause agitation.”

L-carnitine · Natural Medicines adverse-effect record, reported in cluster headache.
4 sources cited

3616. Anon. Carnitor (levocarnitine) package insert. Sigma-Tau Pharmaceuticals Inc, Gaithersburg, MD. December 1999.

58554. Malaguarnera, M., Vacante, M., Avitabile, T., Malaguarnera, M., Cammalleri, L., and Motta, M. L-Carnitine supplementation reduces oxidized LDL cholesterol in patients with diabetes. Am J Clin.Nutr 2009;89(1):71-76. PubMed

95070. Chen N, Yang M, Zhou M, Xiao J, Guo J, He L. L-carnitine for cognitive enhancement in people without cognitive impairment. Cochrane Database Syst Rev. 2017;3:CD009374. PubMed

111891. Moustafa I, Connolly C, Anis M, Mustafa H, Oosthuizen F, Viljoen M. A prospective study to evaluate the efficacy and safety of vitamin E and levocarnitine prophylaxis against doxorubicin-induced cardiotoxicity in adult breast cancer patients. J Oncol Phar PubMed
Phentermine, Topiramate

Listed in the ADVERSE REACTIONS section of the FDA label for Phentermine, Topiramate. Read the label on DailyMed ›
Chest pain Worth acting on Additional detail
L-carnitine
“According to population research, plasma L-carnitine levels are associated with increased risk of cardiovascular disease and major cardiac events. However, oral supplementation with L-carnitine does not appear to be associated with an increased risk of cardiovascular disease.”

L-carnitine · Natural Medicines adverse-effect record, reported in angina.
3 sources cited

90635. Koeth RA, Wang Z, Levison BS, Buffa JA, Org E, Sheehy BT, Britt EB, Fu X, Wu Y, Li L, Smith JD, DiDonato JA, Chen J, Li H, Wu GD, Lewis JD, Warrier M, Brown JM, Krauss RM, Tang WH, Bushman FD, Lusis AJ, Hazen SL. Intestinal microbiota metabolism of L-carn

59037. DiNicolantonio, J. J., Lavie, C. J., Fares, H., Menezes, A. R., and O'Keefe, J. H. L-carnitine in the secondary prevention of cardiovascular disease: systematic review and meta-analysis. Mayo Clin Proc. 2013;88(6):544-551. PubMed

90630. Shang R, Sun Z, Li H. Effective dosing of L-carnitine in the secondary prevention of cardiovascular disease: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2014 Jul 21;14:88. PubMed
Phentermine, Topiramate

Listed in the ADVERSE REACTIONS section of the FDA label for Phentermine, Topiramate. Read the label on DailyMed ›
Heartburn / Reduced appetite / Stomach upset / Stomach pain / Diarrhea Additional detail
L-carnitine
“Orally and intravenously, L-carnitine has been associated with nausea, epigastric discomfort, vomiting, abdominal cramps, heartburn, gastritis, anorexia, and diarrhea. Orally, diarrhea or colitis symptoms, nausea and abdominal pain, indigestion, and constipation have been reported in various clinical trials.”

L-carnitine · Natural Medicines adverse-effect record, reported in anorexia.
6 sources cited

3616. Anon. Carnitor (levocarnitine) package insert. Sigma-Tau Pharmaceuticals Inc, Gaithersburg, MD. December 1999.

3624. Cherchi A, Lai C, Angelino F, et al. Effects of L-carnitine on exercise tolerance in chronic stable angina: a multicenter, double-blind, randomized, placebo-controlled, crossover study. Int J Clin Pharmacol Ther Toxicol 1985;23:569-72.

59030. Tarighat, Esfanjani A., Mahdavi, R., Ebrahimi, Mameghani M., Talebi, M., Nikniaz, Z., and Safaiyan, A. The effects of magnesium, L-carnitine, and concurrent magnesium-L-carnitine supplementation in migraine prophylaxis. Biol.Trace Elem.Res 2012;150(1-3): PubMed

95069. An JH, Kim YJ, Kim KJ, et al. L-carnitine supplementation for the management of fatigue in patients with hypothyroidism on levothyroxine treatment: a randomized, double-blind, placebo-controlled trial. Endocr J. 2016;63(10):885-95. PubMed

95070. Chen N, Yang M, Zhou M, Xiao J, Guo J, He L. L-carnitine for cognitive enhancement in people without cognitive impairment. Cochrane Database Syst Rev. 2017;3:CD009374. PubMed

101562. Khajeh B, Dashti-Khavidaki S, Nasiri-Toosi M, Mohammadi K, Jafari A. Effects of pre-transplant L-carnitine supplementation on primary graft dysfunction in liver transplant recipients: a pilot, randomized, placebo-controlled clinical trial. Res Pharm Sci. PubMed
Phentermine, Topiramate

Listed in the ADVERSE REACTIONS section of the FDA label for Phentermine, Topiramate. Read the label on DailyMed ›
Anxiety or restlessness / Headache reported in 6.3% of FDA reports for Phentermine, Topiramate Additional detail

L-carnitine

Recorded for L-carnitine in the same Natural Medicines adverse-effect record shown under Seizures above.

Phentermine, Topiramate

Listed in the ADVERSE REACTIONS section of the FDA label for Phentermine, Topiramate, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›
Constipation Additional detail

L-carnitine

Recorded for L-carnitine in the same Natural Medicines adverse-effect record shown under Heartburn / Reduced appetite / Stomach upset / Stomach pain / Diarrhea above.

Phentermine, Topiramate

Listed in the ADVERSE REACTIONS section of the FDA label for Phentermine, Topiramate. Read the label on DailyMed ›

Showing the 10 most notable of 12 shared effects — ranked by how unusual each one is, not just whether both lists mention it.

Reported for L-carnitine but not commonly for Phentermine, Topiramate: a heart attack, heart failure, dry skin and vomiting.

Effects for Phentermine, Topiramate come from the ADVERSE REACTIONS section of its FDA label; effects for L-carnitine come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 5,775 voluntary FDA FAERS reports for Phentermine, Topiramate 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.

Special populations

L-carnitine in Pregnancy & Breastfeeding

Lactation Possibly Safe

When used orally. Supplemental doses of L-carnitine have been given to infants in breast milk and formula with no reported adverse effects. The effects of large doses used while nursing are unknown, but L-carnitine is secreted in the breast milk.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About L-carnitine or Phentermine, Topiramate

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers L-carnitine or Phentermine, Topiramate, 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 Phentermine, Topiramate

This page covers L-carnitine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phentermine, Topiramate page lists 125 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 · 101 moderate · 17 minor.

From our pharmacist’s overview on the Phentermine, Topiramate page

“Alcohol is the single biggest hazard on this page. Beer and wine both carry major-rated interactions with Qsymia (phentermine and topiramate), because topiramate already slows the nervous system and drinking deepens that sedation.”

Reviewed by 2 · Jul 18, 2026

Open the Phentermine, Topiramate interaction page

One more smart check

Taking L-carnitine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,350 real supplement products containing L-carnitine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides L-carnitine. Even though L-carnitine itself has no known interaction with Phentermine, Topiramate, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where L-carnitine and Phentermine, Topiramate 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 L-carnitine

Top 10%

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

29 days ago today

Medication Phentermine, Topiramate

Top 10%

#264 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 L-carnitine reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The L-carnitine and Phentermine, Topiramate records this page draws on were last updated July 11, 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About L-carnitine

What is L-carnitine?

Exercise performance and recovery
Heart health
Weight management
Energy and fatigue
Male fertility
Carnitine deficiency

L-carnitine is a compound your body makes naturally and also gets from foods like meat. It helps cells turn fat into energy, and supplements are most clearly useful for people with a true carnitine deficiency. For most other uses, like weight loss or boosting athletic performance, the evidence is mixed or limited, so talk with your pharmacist or doctor before trying it.

Capsules, tablets, oral liquid, powder, and injectable (prescription) forms

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

L-carnitine: dosing

There is no single standard dose of L-carnitine that fits everyone, and the right amount depends on the form and the reason for use. Prescription carnitine for true deficiency is dosed by a doctor based on medical needs.For over-the-counter supplements, the best approach is to follow the directions on the product label and not exceed the recommended amount.

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

Read the full L-carnitine monograph & all interactions

Keep checking

Other Drugs & L-carnitine

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

0Major

19Moderate

0Minor

2,810No known interaction

19 Moderate 2,810 No interaction

Moderate

19 interactions

No interaction 2,810 drugs checked — show the list

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

Showing the 60 most looked-up of 2,810 medications checked with no known interaction — see the full L-carnitine list.

See the full L-carnitine interactions page

See every supplement checked against Phentermine, Topiramate, ranked by severity

Evidence & sources

L-carnitine References

The 41 references that drive our L-carnitine 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.

Ellaway CM, Williams K, Leonard H, et al. Rett syndrome: randomized controlled trial of L-carnitine. J Child Neurol 1999;14:162-7. PubMed
Anon. Carnitor (levocarnitine) package insert. Sigma-Tau Pharmaceuticals Inc, Gaithersburg, MD. December 1999.
Cherchi A, Lai C, Angelino F, et al. Effects of L-carnitine on exercise tolerance in chronic stable angina: a multicenter, double-blind, randomized, placebo-controlled, crossover study. Int J Clin Pharmacol Ther Toxicol 1985;23:569-72.
Plioplys AV, Plioplys S. Amantadine and L-carnitine treatment of Chronic Fatigue Syndrome. Neuropsychobiology 1997;35:16-23. PubMed
Benvenga S, Ruggeri RM, Russo A, et al. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. J Clin Endocrinol Meta
Martinez E, Domingo P, Roca-Cusachs A. Potentiation of acenocoumarol action by L-carnitine. J Intern Med 1993;233:94.
Bachmann HU, Hoffmann A. Interaction of food supplement L-carnitine with oral anticoagulant acenocoumarol. Swiss Med Wkly 2004;134:385. PubMed
Evans AM, Fornasini G. Pharmacokinetics of L-carnitine. Clin Pharmacokinet 2003;42:941-67. PubMed
12761 Benvenga S, Amato A, Calvani M, Trimarchi F. Effects of carnitine on thyroid hormone action. Ann N Y Acad Sci 2004;1033:158-67. PubMed
Ciacci C, Peluso G, Iannoni E, et al. L-Carnitine in the treatment of fatigue in adult celiac disease patients: a pilot study. Dig Liver Dis 2007;39:922-8. PubMed
Cruciani RA, Dvorkin E, Homel P, et al. Safety, tolerability and symptom outcomes associated with L-carnitine supplementation in patients with cancer, fatigue, and carnitine deficiency: a phase I/II study. J Pain Symptom Manage 2006;32:551-9. PubMed
Lebrun C, Alchaar H, Candito M, et al. Levocarnitine administration in multiple sclerosis patients with immunosuppressive therapy-induced fatigue. Mult Scler 2006;12:321-4. PubMed
Malaguarnera M, Cammalleri L, Gargante MP, et al. L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial. Am J Clin Nutr 2007;86:1738-44. PubMed
Mantovani G, Maccio A, Madeddu C, et al. Randomized phase III clinical trial of five different arms of treatment in 322 patients with cancer cachexia. Oncologist 2010;15:200-11.
Angelova-Fischer I, Rippke F, Fischer TW, Neufang G, Zillikens D. A double-blind, randomized, vehicle-controlled efficacy assessment study of a skin care formulation for improvement of mild to moderately severe acne. J Eur Acad Dermatol Venereol. 2013 Jul PubMed
Hatamkhani S, Khalili H, Karimzadeh I, Dashti-Khavidaki S, Abdollahi A, Jafari S. Carnitine for prevention of antituberculosis drug-induced hepatotoxicity: a randomized, clinical trial. J Gastroenterol. Hepatol. 2014 May;29(5):997-1004. PubMed
Boehm G, Stahl B. Oligosaccharides from milk. J Nutr 2007;137(3 Suppl 2):847S-849S.
Van Oudheusden, L. J. and Scholte, H. R. Efficacy of carnitine in the treatment of children with attention-deficit hyperactivity disorder. Prostaglandins Leukot.Essent.Fatty Acids 2002;67(1):33-38. PubMed
Derosa, G., Cicero, A. F., Gaddi, A., Mugellini, A., Ciccarelli, L., and Fogari, R. The effect of L-carnitine on plasma lipoprotein(a) levels in hypercholesterolemic patients with type 2 diabetes mellitus. Clin Ther 2003;25(5):1429-1439. PubMed
Foitzik, K., Hoting, E., Heinrich, U., Tronnier, H., and Paus, R. Indications that topical L-carnitin-L-tartrate promotes human hair growth in vivo. J Dermatol.Sci 2007;48(2):141-144. PubMed
Kumar, A., Singh, R. B., Saxena, M., Niaz, M. A., Josh, S. R., Chattopadhyay, P., Mechirova, V., Pella, D., and Fedacko, J. Effect of carni Q-gel (ubiquinol and carnitine) on cytokines in patients with heart failure in the Tishcon study. Acta Cardiol. 20
Cruciani, R. A., Dvorkin, E., Homel, P., Culliney, B., Malamud, S., Lapin, J., Portenoy, R. K., and Esteban-Cruciani, N. L-carnitine supplementation in patients with advanced cancer and carnitine deficiency: a double-blind, placebo-controlled study. J Pa PubMed
Malaguarnera, M., Vacante, M., Avitabile, T., Malaguarnera, M., Cammalleri, L., and Motta, M. L-Carnitine supplementation reduces oxidized LDL cholesterol in patients with diabetes. Am J Clin.Nutr 2009;89(1):71-76. PubMed
Alvarez, T. M., Guardiola, P. D., Roldan, J. O., Elviro, R., Wevers, R., and Guijarro, G. [Primary trimethylaminuria: the fish odor syndrome]. Endocrinol.Nutr. 2009;56(6):337-340.
Wu, Z. M., Lu, X., Wang, Y. W., Sun, J., Tao, J. W., Yin, F. H., and Cheng, H. J. [Short-term medication of L-carnitine before intracytoplasmic sperm injection for infertile men with oligoasthenozoospermia]. Zhonghua Nan.Ke.Xue 2012;18(3):253-256.
Tarighat, Esfanjani A., Mahdavi, R., Ebrahimi, Mameghani M., Talebi, M., Nikniaz, Z., and Safaiyan, A. The effects of magnesium, L-carnitine, and concurrent magnesium-L-carnitine supplementation in migraine prophylaxis. Biol.Trace Elem.Res 2012;150(1-3): PubMed
DiNicolantonio, J. J., Lavie, C. J., Fares, H., Menezes, A. R., and O'Keefe, J. H. L-carnitine in the secondary prevention of cardiovascular disease: systematic review and meta-analysis. Mayo Clin Proc. 2013;88(6):544-551. PubMed
Huang, W. W., Wang, M. Y., Shi, H. M., Peng, Y., Peng, C. S., Zhang, M., Li, Y., Lu, J., and Li, X. B. Comparative study of bioactive constituents in crude and processed Glycyrrhizae radix and their respective metabolic profiles in gastrointestinal tract
Madsen KL, Preisler N, Orngreen MC, Andersen SP, Olesen JH, Lund AM, Vissing J. Patients with medium-chain acyl-coenzyme a dehydrogenase deficiency have impaired oxidation of fat during exercise but no effect of L-carnitine supplementation. J Clin Endocri
Prohaska ES, Muzyk AJ, Rivelli SK. Levocarnitine-induced hypophosphatemia in a hemodialysis patient with acute valproic acid toxicity. J Neuropsychiatry Clin Neurosci. 2012 Winter;24(1):E18-9. PubMed
Shang R, Sun Z, Li H. Effective dosing of L-carnitine in the secondary prevention of cardiovascular disease: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2014 Jul 21;14:88. PubMed
Zhang JJ, Wu ZB, Cai YJ, Ke B, Huang YJ, Qiu CP, Yang YB, Shi LY, Qin J. L-carnitine ameliorated fasting-induced fatigue, hunger, and metabolic abnormalities in patients with metabolic syndrome: a randomized controlled study. Nutr J. 2014 Nov 26;13:110. PubMed
Koeth RA, Wang Z, Levison BS, Buffa JA, Org E, Sheehy BT, Britt EB, Fu X, Wu Y, Li L, Smith JD, DiDonato JA, Chen J, Li H, Wu GD, Lewis JD, Warrier M, Brown JM, Krauss RM, Tang WH, Bushman FD, Lusis AJ, Hazen SL. Intestinal microbiota metabolism of L-carn
Jun DW, Kim BI, Cho YK, Kim HJ, Kwon YO, Park SY, Han SY, Baek YH, Jung YJ, Kim HY, Kim W, Heo J, Woo HY, Hwang SG, Rim KS, Choi JY, Bae SH, Lee YS, Lim YS,Cheong JY, Cho SW, Lee BS, Kim SH, Sohn JH, Kim TY, Paik YH, Kim JK, Lee KS. Efficacy and safety of
An JH, Kim YJ, Kim KJ, et al. L-carnitine supplementation for the management of fatigue in patients with hypothyroidism on levothyroxine treatment: a randomized, double-blind, placebo-controlled trial. Endocr J. 2016;63(10):885-95. PubMed
Chen N, Yang M, Zhou M, Xiao J, Guo J, He L. L-carnitine for cognitive enhancement in people without cognitive impairment. Cochrane Database Syst Rev. 2017;3:CD009374. PubMed
Khajeh B, Dashti-Khavidaki S, Nasiri-Toosi M, Mohammadi K, Jafari A. Effects of pre-transplant L-carnitine supplementation on primary graft dysfunction in liver transplant recipients: a pilot, randomized, placebo-controlled clinical trial. Res Pharm Sci. PubMed
Kubota K, Uojima H, Shao X, et al. Additional L-carnitine Reduced the Risk of Hospitalization in Patients with Overt Hepatic Encephalopathy on Rifaximin. Dig Dis 2021. PubMed
Amini L, Yaghini O, Ghazavi M, Aslani N. L-carnitine versus propranolol for pediatric migraine prophylaxis. Iran J Child Neurol 2021;15(2):77-86.
Shakibaei F, Jelvani D. Effect of adding l -carnitine to risperidone on behavioral, cognitive, social, and physical symptoms in children and adolescents with autism: A randomized double-blinded placebo-controlled clinical trial. Clin Neuropharmacol 2023;4 PubMed
Moustafa I, Connolly C, Anis M, Mustafa H, Oosthuizen F, Viljoen M. A prospective study to evaluate the efficacy and safety of vitamin E and levocarnitine prophylaxis against doxorubicin-induced cardiotoxicity in adult breast cancer patients. J Oncol Phar 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.

Related: nutrient depletion

Phentermine, Topiramate Is Linked to Lower Levels of One Nutrient

Natural Medicines records Phentermine, Topiramate as a medicine that can lower these. This is not an interaction with L-carnitine — it is a separate effect of the medicine, and it is a reason some people are advised to supplement rather than to avoid one:

VITAMIN K›

Read the full Phentermine, Topiramate nutrient depletion report ›

L-carnitine is itself a nutrient we track — see which medications may deplete L-CARNITINE.

Depletion records come from the licensed Natural Medicines database. Do not start a supplement on the strength of this page — ask your pharmacist or doctor whether it applies to you.

Pharmacist Counseling Corner

Taking L-carnitine and Phentermine, Topiramate Together: Common Questions

Is it safe to take L-carnitine with Phentermine, Topiramate?

We do not list a known interaction between L-carnitine and Phentermine, Topiramate. 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 L-carnitine and Phentermine, Topiramate have any of the same side effects?

Yes — our sources link each of them separately to 10 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.

How was the L-carnitine and Phentermine, Topiramate combination checked?

Interactions in our licensed database are recorded against drug classes. Phentermine, Topiramate is filed under 6 classifications, and L-carnitine has documented interactions with 3 drug classes — none of Phentermine, Topiramate's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.

Does L-carnitine interact with any other medications?

Yes. L-carnitine has 19 documented drug interactions in our database — Phentermine, Topiramate is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

Does Phentermine, Topiramate interact with any supplements?

Yes. Phentermine, Topiramate has documented interactions with 125 supplements in our database — L-carnitine is not one of them. The Phentermine, Topiramate 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

L-carnitine monograph Uses, safety profile, and every drug interaction in one place Phentermine, Topiramate supplement interactions Every supplement checked against Phentermine, Topiramate, 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 41 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phentermine, Topiramate and L-carnitine?

Our pharmacists answer your medication & supplement questions — free.

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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.