In 30 seconds
- Yes, you can take them together: the US NIH fact sheet on L-carnitine lists no interactions with caffeine.
- In a study of 5 rugby players, L-carnitine with caffeine extended exercise time more than either one on its own.
- In a meta-analysis of 19 studies, caffeine before exercise increased the use of fat for energy, at doses above 3 mg per kilo.
- EFSA considers up to 200 mg of caffeine in one go and 400 mg a day safe. A filter coffee contains about 90 mg.
Yes, you can take L-carnitine with coffee. L-carnitine contains no caffeine, so it adds no stimulants to your cup, and in one study the two together extended exercise time more than either one alone 5.
Here is what each one does, what the studies combining them found and how to plan them without overdoing the caffeine.
Is there any interaction?
The US NIH fact sheet on L-carnitine lists none with caffeine. The interactions it mentions are with pivalate-conjugated antibiotics and some anti-epileptic drugs, such as valproic acid 1.
If you take any of these medicines, check with your doctor before taking L-carnitine, with or without coffee.
What each one does
- L-carnitine. According to physiology studies, it carries fatty acids into the mitochondria and takes part in their oxidation, which is why it is studied as a fat burner 2. In a meta-analysis of 9 trials with 911 adults, at 1.8-4 g a day, those who took it lost 1.33 kg more weight than with placebo 2. You will find the diagram in what L-carnitine is good for.
- Caffeine. It stimulates the nervous system, the heart and the muscles. In studies, 100 mg raised energy expenditure by about 9.2 kcal an hour more than placebo, for 3 hours or more 2.
They complement each other over time. Caffeine acts in the moment; L-carnitine is studied as a daily dose taken for 30 to 360 days 2.
What the studies say
| Study | What was tested | Result |
|---|---|---|
| Cha et al., 2001: 5 rugby players | L-carnitine, caffeine or both together, in a cycling test to exhaustion | With both together, exercise time increased more than with either one alone |
| Wall et al., 2023: 6 adults | A high dose of caffeine during 5 hours of intravenous L-carnitine | Carnitine cleared from the blood faster: about 15% lower over the last hour and a half |
| Collado-Mateo et al., 2020: 19 studies | Caffeine before exercise, after fasting | More fat used for energy, at doses above 3 mg per kilo |
| Fernández-Sánchez et al., 2024: 18 trials | Caffeine before exercise, after a meal | More fat used for energy, at doses below 6 mg per kilo |
Sources: Cha et al., 2001; Wall et al., 2023; Collado-Mateo et al., 2020; Fernández-Sánchez et al., 2024.
The two together
Few studies combine them, and they are small. In the first, 5 rugby players did a cycling test to exhaustion with L-carnitine, with caffeine, with both or with neither. L-carnitine alone extended exercise time compared with the control, and with both together the effect was greater than with either one alone 5.
In 2023, another study gave 6 adults intravenous L-carnitine for 5 hours, with caffeine or with placebo. With caffeine, carnitine cleared from the blood faster: about 15% lower over the last hour and a half 6.
The authors believe caffeine activated the cells' sodium-potassium pump, which helps carnitine enter the muscle. They suggest taking the two together as a possible way to load the muscle with carnitine 6. It is an idea still to be confirmed: they did not measure muscle carnitine. And they used 9 mg of caffeine per kilo, more than EFSA considers safe over an entire day 7. It is not a regimen to copy.
Caffeine and fat
Here there are more studies. A meta-analysis of 19 studies, all carried out after fasting, found that caffeine taken before exercise increased the use of fat for energy. It took more than 3 mg per kilo, and the effect was larger in sedentary or less-trained people 3.
Another meta-analysis of 18 trials with 228 people tested it after a meal: fat use also rose, at doses below 6 mg per kilo 4. For everything caffeine does in sport, see caffeine and performance.
Caffeine before exercise
What the meta-analyses measured
How much caffeine: your cup and the limits
| Drink | Caffeine |
|---|---|
| Filter coffee (200 ml) | 90 mg |
| Espresso (60 ml) | 80 mg |
| Can of energy drink (250 ml) | 80 mg |
| Tea (220 ml) | 50 mg |
| Can of cola (355 ml) | 40 mg |
Source: EFSA, as reported by EUFIC; values vary with preparation.
EFSA considers that, in healthy adults 7:
- Up to 200 mg in one go, about 3 mg per kilo, raises no safety concerns, even less than 2 hours before intense exercise.
- Up to 400 mg a day, spread out, does not either.
- Around 100 mg close to bedtime can affect some people's sleep.
- During pregnancy, the limit drops to 200 mg a day.
The effect on fat appeared above 3 mg per kilo 3, and EFSA puts the safe single dose at about 3 mg per kilo 7. There is no point going further: stick to your usual coffee or two 8.
How to take them together
- Your coffee, before training. The studies gave caffeine 30 to 75 minutes beforehand, usually 60 3.
- Your L-carnitine, 30 minutes before. There is no need to mix it into your coffee. If you train first thing without breakfast, that works too: we explain it in L-carnitine on an empty stomach.
- If you train later in the day, skip the coffee. L-carnitine contains no stimulants, so it works at any time. See how late caffeine suits you in caffeine and sleep.
- On rest days, take L-carnitine with a meal and have your coffee whenever you like.
If you are unsure about when to take L-carnitine, we cover it in L-carnitine: before or after training?.
Step by step
Coffee and L-carnitine before training
If your fat burner already contains caffeine
Many fat burners contain caffeine, either added or from plants that contain it, such as guarana, kola nut or yerba mate. Some labels do not say how much they contain, and combined with other stimulants, such as bitter orange, its adverse effects can increase 2.
Add your coffees on top. Three filter coffees already come to about 270 mg 8, and with a caffeine-based fat burner it is easy to go over 400 mg a day 7.
That is why many people prefer a stimulant-free fat burner if they already drink coffee: L-carnitine and CLA add not a single milligram of caffeine. We compare them with the rest in fat burners: which ones work, according to the studies and show you how to combine them in CLA and L-carnitine together.
If you are pregnant, take medication or have a heart condition, check with your doctor first.
Frequently asked questions
Can you take L-carnitine with coffee?
Yes. The US NIH fact sheet on L-carnitine lists no interaction with caffeine; the ones it mentions involve certain antibiotics and anti-epileptic drugs.
Can I mix liquid L-carnitine into my coffee?
The practical approach is to have your coffee and, 30 minutes before training, your 20 ml of L-carnitine.
How much coffee can I drink with L-carnitine?
The same as without it. EFSA considers up to 200 mg of caffeine in one go and 400 mg a day safe for healthy adults. A filter coffee contains about 90 mg and an espresso about 80 mg.
Does L-carnitine contain caffeine?
L-carnitine is not a stimulant, although some products add caffeine or synephrine to it: check the label. Without them, you can take it even if you already drink coffee or train later in the day.
Can you take coffee and L-carnitine on an empty stomach?
Yes. In the meta-analysis of 19 studies, all carried out after fasting, caffeine before exercise increased the use of fat for energy.
Sources
- Office of Dietary Supplements, National Institutes of Health. Carnitine: fact sheet for health professionals. View publication
- Office of Dietary Supplements, National Institutes of Health. Dietary supplements for weight loss: fact sheet for health professionals. View publication
- Collado-Mateo D, Lavín-Pérez AM, Merellano-Navarro E, Del Coso J. Effect of acute caffeine intake on the fat oxidation rate during exercise: a systematic review and meta-analysis. Nutrients. 2020;12(12):3603. View publication
- Fernández-Sánchez J, Trujillo-Colmena D, Rodríguez-Castaño A, Lavín-Pérez AM, Del Coso J, Casado A, Collado-Mateo D. Effect of acute caffeine intake on fat oxidation rate during fed-state exercise: a systematic review and meta-analysis. Nutrients. 2024;16(2):207. View publication
- Cha YS, Choi SK, Suh H, Lee SN, Cho D, Lim K. Effects of carnitine coingested caffeine on carnitine metabolism and endurance capacity in athletes. J Nutr Sci Vitaminol (Tokyo). 2001;47(6):378-384. View publication
- Wall BT, Machin D, Dunlop MV, Stephens FB. Caffeine ingestion stimulates plasma carnitine clearance in humans. Physiol Rep. 2023;11(4):e15615. View publication
- EFSA. Caffeine. Topic page on the European Food Safety Authority's scientific opinion on the safety of caffeine, 2015. View publication
- EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific opinion on the safety of caffeine. EFSA Journal. 2015;13(5):4102. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product. A varied and balanced diet and a healthy lifestyle are important.
