L-carnitine + Glycerol Phenylbutyrate
Glycerol Phenylbutyrate brand name: Ravicti.
We found no known interaction between L-carnitine and Glycerol Phenylbutyrate 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 label for Glycerol Phenylbutyrate states a food rule worth keeping to, and 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.
L-carnitine and Glycerol Phenylbutyrate
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 Glycerol Phenylbutyrate 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
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.
Why No Interaction Is Listed for Glycerol Phenylbutyrate
Interactions in our licensed database are recorded against drug classes, not just single drug names. Glycerol Phenylbutyrate is filed under a single classification — oral drugs. 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 Glycerol Phenylbutyrate’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.
L-carnitine Does Interact With Other Medications
L-carnitine has 19 moderate known drug interactions in our database — Glycerol Phenylbutyrate isn’t one of them. If you take anything else, check it against the full list below.
Check Another of Your Medications Against L-carnitine
We haven’t checked that one against L-carnitine yet — ask our pharmacists directly.
Covers the 2,830 medications we’ve checked against L-carnitine. Pick one to open its full report.
L-carnitine in Pregnancy & Breastfeeding
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
Some Glycerol Phenylbutyrate Products Have a Food Rule — L-carnitine Should Not Break It
At least one FDA label for a product containing Glycerol Phenylbutyrate says to take it with food. If you take L-carnitine on an empty stomach out of habit, keep them separate — and take Glycerol Phenylbutyrate with a meal where the label says to.
This may not be true of your version. Food instructions belong to the product, not the ingredient: two Glycerol Phenylbutyrate products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.
Instruct patients to take glycerol phenylbutyrate oral liquid with food or formula and to administer directly into the mouth via oral syringe.
From the Dosage and Administration section of the FDA label we read for Glycerol Phenylbutyrate — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›
A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.
Questions About L-carnitine or Glycerol Phenylbutyrate
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 Glycerol Phenylbutyrate, 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:
- Is Tirzepatide Safe With L-Carnitine and Herbal Supplements? ›
- Can You Take L-Carnitine With Xarelto (Rivaroxaban)? ›
Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.
See Every Supplement That Interacts With Glycerol Phenylbutyrate
This page covers L-carnitine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Glycerol Phenylbutyrate page lists 17 supplements it has a documented interaction with, worst first, each one explained.
The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).
By severity: 1 major · 7 moderate · 9 minor.
From our pharmacist’s overview on the Glycerol Phenylbutyrate page
“Ravicti (glycerol phenylbutyrate) pulls ammonia out of the blood in people with urea cycle disorders, so a dose that never gets absorbed is not a small problem, it can let ammonia climb toward dangerous levels. That is why this list deserves real attention even though it is short.”
Reviewed by 2 · Jul 18, 2026
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 Glycerol Phenylbutyrate, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:
Where L-carnitine and Glycerol Phenylbutyrate 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.
#84 of 1,452 supplements looked up here in the last 7 days
#136 of 2,830 medications looked up here in the last 7 days
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 October 4, 2026. The L-carnitine and Glycerol Phenylbutyrate 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.
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.
About Glycerol Phenylbutyrate
What Is Glycerol Phenylbutyrate Used For?
Brand name: Ravicti
Glycerol phenylbutyrate (sold as Ravicti and as a generic oral liquid) is used for the long-term management of urea cycle disorders (UCDs). These are inherited conditions in which the body cannot clear waste nitrogen as ammonia. It is for people who cannot be managed with a low-protein diet and/or amino acid supplements alone.
It must be used together with dietary protein restriction, and sometimes dietary supplements. It is not for sudden (acute) high ammonia, which needs faster-acting treatment. Safety and effectiveness for NAGS deficiency (a type of UCD) have not been established.
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.
No drugs match “”.
19 interactions
- Levothyroxine ›
- Conjugated Estrogens ›
- Testosterone Undecanoate ›
- Levothyroxine Sodium ›
- Liotrix ›
- Warfarin Sodium ›
- Desiccated Thyroid Extract ›
- Desiccated Thyroid Extract (prescription Drug) ›
- Menotropins ›
- Acenocoumarol ›
- Dextrothyroxine ›
- Human Chorionic Gonadotropin (hcg) ›
- Liothyronine ›
- Ospemifene ›
- Thyroglobulin ›
- Thyroid Hormone ›
- Warfarin ›
- Levothyroxine, Liothyronine ›
- Liotrix, T4/t3 ›
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.
- Apixaban ›
- Amlodipine ›
- Methylphenidate ›
- Ivermectin ›
- Abemaciclib ›
- Testosterone ›
- Losartan Potassium ›
- Sertraline ›
- Acetaminophen ›
- Rosuvastatin ›
- Aspirin ›
- Metoprolol ›
- Escitalopram ›
- Clopidogrel ›
- Atorvastatin ›
- Rivaroxaban ›
- Isotretinoin ›
- Tirzepatide ›
- Ibuprofen ›
- Amlodipine Besylate ›
- Docusate ›
- Methamphetamine ›
- Prednisone ›
- Metformin ›
- Amitriptyline ›
- Tadalafil ›
- Semaglutide ›
- Lisdexamfetamine ›
- Hydroxyurea ›
- Valacyclovir ›
- Amphetamine ›
- Sumatriptan ›
- Propranolol ›
- Methotrexate ›
- Lisinopril ›
- Amoxicillin ›
- Bupropion ›
- Fluoxetine ›
- Azithromycin ›
- Pregabalin ›
- Doxycycline ›
- Gabapentin ›
- Acetaminophen, Aspirin, Caffeine ›
- Dextroamphetamine ›
- Naproxen ›
- Lamotrigine ›
- Bendamustine ›
- Quetiapine ›
- Clonazepam ›
- Acyclovir ›
- Buspirone ›
- Duloxetine ›
- Omeprazole ›
- Letrozole ›
- Citalopram ›
- Methylene Blue ›
- Ciprofloxacin ›
- Acetaminophen, Codeine ›
- Candesartan Cilexetil ›
- Acetaminophen, Butalbital, Caffeine ›
Showing the 60 most looked-up of 2,810 medications checked with no known interaction — see the full L-carnitine list.
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.
Taking L-carnitine and Glycerol Phenylbutyrate Together: Common Questions
Is it safe to take L-carnitine with Glycerol Phenylbutyrate?
Do L-carnitine and Glycerol Phenylbutyrate have any of the same side effects?
Should I take L-carnitine and Glycerol Phenylbutyrate at the same time of day?
How was the L-carnitine and Glycerol Phenylbutyrate combination checked?
Does L-carnitine interact with any other medications?
Does Glycerol Phenylbutyrate interact with any supplements?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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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.