L-Carnitine Base: How to Read Forms, Amounts and Servings

L-carnitine base is L-carnitine on its own, without an acid attached. Salts such as L-carnitine tartrate and L-carnitine fumarate pair L-carnitine with tartaric or fumaric acid, so part of their weight is not L-carnitine. To know how much L-carnitine a label declares, check which name the milligram (mg) amount sits beside, then read it with the serving size. U.S. rules say the weight listed for an ingredient such as carnitine must be the weight of the ingredient named, not of its source, and the source may follow in parentheses after “as” or “from”. [1] So “L-carnitine (as L-carnitine fumarate) 680 mg” declares 680 mg of L-carnitine, while “L-carnitine tartrate 1,000 mg” is the weight of the salt, with no L-carnitine figure. [2] [3] Labels and label records use “base” or “free form” for L-carnitine alone; one record below notes “free-form base, 1,000 mg”. [4] A label term is not evidence about the finished product, and no source cited here shows one form working better than another.

This page is general education about reading labels. It does not recommend any product or amount. The NIH Office of Dietary Supplements (ODS) says healthy children and adults do not need carnitine from food or supplements, because the liver and kidneys make enough. [5] If you take medicines, have kidney disease or a seizure disorder, or are pregnant or breastfeeding, talk with your doctor or pharmacist before using any carnitine product. [5] [6]

Safety first: ODS says carnitine can cause seizures in people with seizure disorders, and prescription levocarnitine labeling reports seizures in people with or without a history of them. [5] [7] If you have a seizure disorder, ask your doctor before using carnitine, and seek emergency care for a seizure.

Use the ingredient-label checklist

Five L-carnitine labels compared

Method. The table uses five records from the NIH Dietary Supplement Label Database (DSLD), which captures the information printed on supplement labels sold in the United States, and identifies each by its DSLD record number. [8] DSLD records what labels declare, not what products have been tested to contain, and it includes products that are no longer sold, so check any entry against the label you have. [8] The last column shows the first ingredients each label lists outside the Supplement Facts panel.

A salt’s weight is not its L-carnitine content. Label D names L-carnitine tartrate as the ingredient, so its 1,000 mg is the weight of the salt. [3] Federal rules require the declared weight to be that of the ingredient named, and FDA’s own example says to list the weight of calcium rather than of the calcium carbonate that supplies it. [1] [10] As a rough guide, PubChem describes L-carnitine tartrate as two L-carnitine units with one tartrate, molecular weight 472.5, and L-carnitine’s molecular weight is 161.20. [11] [12] By our calculation, L-carnitine is about 68% of that compound’s weight, so 1,000 mg of the pure compound would hold about 680 mg of L-carnitine. Label D does not state a figure, and a commercial ingredient may differ from the pure compound, so ask the manufacturer.

Two fumarate labels, written two ways. Label C gives both numbers: 885 mg of L-carnitine fumarate yielding 500 mg of L-carnitine, which is about 56% by our arithmetic. [6] Label B gives only the L-carnitine figure, 680 mg, and names the fumarate as its source. [2] The servings also differ: label B’s 680 mg is for two capsules, about 340 mg a capsule, while label C’s 500 mg is for one. [2] [6] Compare L-carnitine figures with L-carnitine figures, each with its own serving.

Combined totals. Label E declares one total of 3.15 g from four named forms: acetyl-L-carnitine, glycine propionyl-L-carnitine hydrochloride, L-carnitine and L-carnitine tartrate. [9] When two or more sources supply one ingredient, the rules require all of them to be named in parentheses in descending order by weight, but not the amount of each. [1] ODS uses “carnitine” as a general term for several compounds, including L-carnitine, acetyl-L-carnitine and propionyl-L-carnitine. [5] The label does not say how the total was counted, so ask the manufacturer.

The carrier is listed separately. Both liquids list water first among their other ingredients, and label A also lists glycerin; the capsule labels list cellulose, rice flour or gelatin. [4] [9] [2] [6] [3] FDA says ingredients that are not dietary ingredients, such as binders, excipients and fillers, go in the ingredient statement rather than the Supplement Facts panel. [10] The tartrate or fumarate in a salt is part of the source ingredient, not the carrier. Prescription labeling follows the same split: a levocarnitine tablet label states 330 mg of levocarnitine and names its inactive ingredients separately. [7]

Base and salt terms on a label

• L-carnitine, free form or base. L-carnitine on its own. Prescription labeling calls it levocarnitine and gives its molecular weight as 161.20; its chemical name ends in “inner salt” because one molecule carries both charges, but it is still L-carnitine alone. [7] PubChem lists L-carnitine and levocarnitine as names for the same compound. [12]
• L-carnitine tartrate or L-carnitine L-tartrate. A salt of L-carnitine with tartaric acid, two to one. [11] Read whether the amount is for the salt or for the L-carnitine it supplies.
• L-carnitine fumarate. A salt with fumaric acid. Label C states the L-carnitine it yields; label B lists it as the source of an L-carnitine amount. [6] [2]
• Acetyl-L-carnitine and propionyl-L-carnitine. Related compounds within the general term “carnitine”, not salts of L-carnitine. ODS says the two main forms in supplements are L-carnitine and acetyl-L-carnitine. [5]
• “As” or “from” in parentheses. Names the source; the amount beside it is the ingredient named before the parentheses. [1]
• “Daily Value not established”. Carnitine has no Daily Value, so its line carries a symbol pointing to this footnote instead of a percentage. [1] [10]
• Proprietary blend. The label gives the total weight of the blend’s ingredients, not the amount of each one. [1] [10]

Serving size and totals

FDA defines one serving as the maximum amount the label recommends per occasion, or one unit, such as a capsule, when the label gives no recommendation. [10] Every amount in the table applies to that serving only: two capsules for labels B and D, one capsule for label C and 15 mL for the liquids. [2] [3] [6] [4] [9]

Hypothetical example. Suppose someone had one labeled serving of label A and one of label B on the same day. Together, those labels declare 1,000 mg + 680 mg = 1,680 mg of L-carnitine, before counting any other product or food. [4] [2] ODS says carnitine is found in animal products, especially red meat. [5]

Carnitine has no established upper intake level, but ODS says doses of about 3 g a day from supplements can cause nausea, vomiting, abdominal cramps, diarrhea and a fishy body odor. [5] One labeled serving of label E declares a combined 3.15 g of carnitine forms. [9] ODS describes the evidence on carnitine for exercise performance as mixed, and weight-loss results as equivocal, with larger studies needed. [5] Reading a label carefully does not show that any amount suits you.

For practice reading serving sizes on Nutrition Facts panels, see the food label reading worksheet. Two labels above also list B vitamins, vitamin B6 on label A and thiamine on label E; the guide to a plant based vitamin B complex explains how to check vitamin forms. [4] [9]

Ingredient-label checklist for L-carnitine

Use these steps with each physical label in front of you, and write down the date you checked.

• Find every carnitine line. Look for L-carnitine, levocarnitine, L-carnitine tartrate, L-carnitine fumarate, acetyl-L-carnitine and propionyl-L-carnitine, including inside parentheses. [5] [9] [7]
• See which name the amount sits beside. “L-carnitine (as …)” declares L-carnitine; an amount beside a salt’s own name is the weight of the salt. [1] [10]
• Do not convert a salt weight yourself. If the label gives only the salt’s weight, ask the manufacturer how much L-carnitine it provides. Label C’s own figures (500 mg from 885 mg) do not match a textbook ratio exactly. [6] [3]
• Read the amount with its serving. Note how many capsules or millilitres the amount covers. [10]
• Ask about combined totals and blends. A single total from several forms, or a proprietary blend, does not show how much of each is present. [1] [9]
• Read the other ingredients. The carrier, capsule and flavorings are listed outside the Supplement Facts panel; check them for gelatin or anything else you avoid. [10] [3]
• Add up every product. List each product with carnitine and the servings you actually use. [5]
• Bring the list to your pharmacist or doctor. ODS lists pivalate-conjugated antibiotics, valproic acid and other anticonvulsants among medicines that interact with carnitine. [5] Prescription levocarnitine labeling reports INR increases with warfarin. [7] DailyMed posts the labeling that companies submit to FDA for medicines and some other products; NLM does not review it before publication. [13]
• Match the record to your container and store it safely. DSLD includes off-market labels, so compare any entry with the label you have. [8] Each label above says to keep the product out of reach of children. [4] [2] [6] [3] [9]

Safety notes

• ODS says carnitine can cause muscle weakness in people with uremia and seizures in people with seizure disorders, and that doses of about 3 g a day can cause stomach upset and a fishy body odor. [5]
• The prescription levocarnitine label warns that high doses taken for a long time by people with severely reduced kidney function, or on dialysis, may lead to a build-up of the metabolites TMA and TMAO, and reports serious allergic reactions, including rash, hives and facial swelling, with the oral medicine. [7]
• The same label reports INR increases in people taking warfarin and recommends INR monitoring when levocarnitine is started or its dose changes. [7] If you take warfarin or another blood thinner, ask your prescriber before using any carnitine product.
• Prescription levocarnitine is a medicine used for diagnosed carnitine deficiency. [7] Do not swap it for a supplement or change it without your prescriber.
• ODS advises people who take medicines regularly to discuss their carnitine intake with their health care providers. [5]

Where to go next

Whether you need carnitine, and in what form or amount, is a question for your doctor or pharmacist. More label guides are listed under Ingredients and labels.

Common questions

Is L-carnitine base the same as L-carnitine?

Yes. “Base” or “free form” describes L-carnitine on its own, without tartaric or fumaric acid attached. [4] Prescription labeling calls the same compound levocarnitine. [7] [12]

Is L-carnitine base stronger than L-carnitine tartrate?

Not in itself. A milligram of the salt holds less L-carnitine than a milligram of the base, but labels often state the L-carnitine amount directly, so compare the L-carnitine figures per serving. [1] [2] [6] No source cited here shows one form working better than another, and ODS says absorption of supplemental L-carnitine is about 14% to 18%, less than from food. [5]

What does “L-carnitine (as L-carnitine fumarate)” mean?

The fumarate is the source, and the amount shown is L-carnitine. Federal rules allow the source in parentheses after “as” or “from” and require the weight of the ingredient named. [1]

How much L-carnitine is in 1,000 mg of L-carnitine tartrate?

For the pure two-to-one compound, about 680 mg by our calculation from PubChem molecular weights. [11] [12] A product may differ, so rely on an L-carnitine figure stated on the label or ask the manufacturer. [3]

What is the carrier in a liquid L-carnitine product?

On the two liquids above, water is listed first among the other ingredients, followed on label A by glycerin and on label E by phosphoric acid. [4] [9] These appear in the ingredient statement, not the Supplement Facts panel. [10]

If you have a seizure disorder, ask your doctor before using carnitine, and seek emergency care for a seizure; ODS says carnitine can cause seizures in people with seizure disorders. [5]

Use the ingredient-label checklist

Sources and limitations

1. Electronic Code of Federal Regulations: 21 CFR 101.36, Nutrition labeling of dietary supplements. eCFR text current as of October 8, 2026; paragraphs (b)(3), (c)(3) and (d). Rules for manufacturers; they do not verify any product.
2. NIH Dietary Supplement Label Database: record 293993, L-carnitine capsules. Entered July 18, 2023. Label text as recorded, not a test of contents.
3. NIH Dietary Supplement Label Database: record 223349, L-carnitine tartrate capsules. Entered June 24, 2020. Label text as recorded, not a test of contents.
4. NIH Dietary Supplement Label Database: record 314479, flavored L-carnitine liquid. Entered August 22, 2024. Label text as recorded, not a test of contents.
5. NIH Office of Dietary Supplements: Carnitine, Fact Sheet for Health Professionals. Updated April 17, 2023. Written for health professionals; its medicine list is examples, not complete, and it does not discuss tartrate or fumarate salts.
6. NIH Dietary Supplement Label Database: record 274210, L-carnitine fumarate capsules. Entered September 22, 2022. Label text as recorded, not a test of contents.
7. National Library of Medicine: DailyMed, levocarnitine tablets and oral solution, prescription drug label. Published on DailyMed November 14, 2024. Prescription medicine labeling, not supplement labeling; cited for chemistry, label layout and medicine safety only.
8. NIH Office of Dietary Supplements: Dietary Supplement Label Database, About. Records what labels say; it does not test products, and it includes off-market labels.
9. NIH Dietary Supplement Label Database: record 333964, flavored liquid with several carnitine forms. Entered August 22, 2025. Label text as recorded, not a test of contents; marketing statements on the label are not repeated.
10. U.S. Food and Drug Administration: Dietary Supplement Labeling Guide, Chapter IV. Nutrition Labeling. April 2005; nonbinding recommendations written for manufacturers. Its source-weight example uses calcium, not carnitine.
11. National Center for Biotechnology Information: PubChem, Levocarnitine tartrate (CID 57349413). Chemical reference for the pure compound; commercial ingredients may differ, and it says nothing about any product.
12. National Center for Biotechnology Information: PubChem, Levocarnitine (CID 10917). Chemical reference; says nothing about any product.
13. National Library of Medicine: DailyMed, About. Labeling is submitted by companies and is not reviewed by NLM before publication.