Phenylethylamine (PEA)

What it is

Phenylethylamine is one of the simplest molecules in neurochemistry: a benzene ring with a short amine chain. From this basic scaffold derive dopamine, noradrenaline and adrenaline, but also amphetamine and many designer drugs. PEA itself is produced in the body in tiny amounts and is therefore counted among the trace amines, together with tyramine, tryptamine and octopamine.

In the supplement trade, PEA is usually sold as the hydrochloride, as a single product or as an ingredient in pre-workout, fat burner and mood blends. It is often combined with hordenine. A note on possible confusion: in the trade, the abbreviation PEA also stands for palmitoylethanolamide, an entirely different substance from the field of pain and inflammation. This entry concerns phenylethylamine only.

It is often claimed that chocolate is a source of PEA and explains the feeling of happiness when snacking. An analysis of cocoa products, however, found PEA in only a few samples and in considerably smaller amounts than other biogenic amines. It also occurs in traces in wine.

How it is supposed to work

For a long time PEA was considered a by-product with no function of its own. That changed in 2001 with the discovery of a dedicated receptor family for trace amines, the TAARs. The most important of these, TAAR1, occurs mainly in limbic brain regions and in areas of the messengers dopamine and noradrenaline that are involved in mood, attention and addiction. PEA is a full agonist at TAAR1 and serves as a reference substance in research. Exactly what role TAAR1 plays in everyday life, however, is still disputed.

On top of this comes an amphetamine-like effect. In a cell study, PEA inhibited the noradrenaline transporter with an IC50 of 0.05 µM and the dopamine transporter with 1.8 µM. D-amphetamine was at 0.09 and 1.3 µM in the same experiment, that is, in the same order of magnitude. PEA had no effect at the serotonin transporter. That would be the basis for the described drive: more noradrenaline and dopamine between the nerve cells.

The decisive difference from amphetamine is breakdown. PEA is broken down by monoamine oxidase B, and so rapidly that the depression studies of the 1990s specifically added an MAO-B inhibitor. After a single intake, doping laboratories found little or no increase in PEA in urine; only its breakdown products rose. This suggests that a large part is already metabolized on swallowing.

Hordenine: the companion in the stack

Hordenine is an alkaloid from germinating barley and is therefore also found in beer. Chemically it is an N,N-dimethyl derivative of tyramine and thus a relative of PEA. In the scene it is combined with PEA because it is also broken down by MAO-B and is thus supposed to slow the breakdown of PEA. It is established that hordenine is a highly selective MAO-B substrate in rat liver. Whether this makes PEA act longer in humans has not been studied by anyone.

A finding from 2017 is interesting in its own right: in a cell experiment, hordenine activates the dopamine D2 receptor, with a binding strength of 13 µM. In humans there are only pharmacokinetic data. After drinking beer, the half-life in 4 volunteers was between 52.7 and 66.4 minutes; after a supplement it averaged 54 minutes. The authors of the beer study consider the levels reached too low for a direct receptor effect. There are no studies with hordenine on mood, focus or fat loss.

What the studies show

The PEA hypothesis of depression

From the 1970s onward, the research group around Sabelli pursued the idea that a PEA deficiency explains one form of depression. In 1986 it found less phenylacetic acid in the plasma of 23 untreated depressed patients than in 12 healthy people, and in urine 78.2 versus 141.1 mg per day. The idea has never been tested in large studies, but remains an original approach.

PEA plus selegiline in depression

In a 1996 follow-up, 14 people with major depression had responded to PEA, always combined with the MAO-B inhibitor selegiline, which was meant to prevent its breakdown. After 20 to 50 weeks, the improvement persisted in 12 of them; no side effects were noted. There was neither a control group nor blinding, and the effect cannot be separated from that of selegiline.

The only placebo study

The only randomized, placebo-controlled, double-blind study with swallowed PEA comes from food research in 1983. 27 healthy people received PEA, histamine or tyramine in apple juice. Only PEA triggered headache, dizziness and malaise in some of them. Symptoms were measured, not mood or performance.

What reaches the urine

Since PEA was added to the doping list in 2015, laboratories have investigated how intake can be detected. In one study, PEA in urine rose only moderately after a single dose, in a second not at all, while breakdown products increased markedly. This confirms the rapid breakdown.

Where the data stop

The promises with which PEA is sold lack a foundation. There is no controlled study showing more focus, better mood, more training performance or fat loss after taking PEA. The depression data are uncontrolled, come essentially from one research group and use a medicinal drug as a partner. How much swallowed PEA actually reaches the brain has not been measured.

The stack logic with hordenine is also untested: that it protects PEA from breakdown is an inference from rat experiments, not a measurement in humans.

Status, approval and legal

In Germany, PEA is approved neither as a medicine nor as a food ingredient. The EU Novel Food Catalogue has no entry for PEA or hordenine, and neither does the Union list of authorized novel foods. Authorities in the Czech Republic, Poland and Slovenia have reported PEA in food supplements via the EU rapid alert system, Slovenia in 2025 as an unauthorized novel ingredient; Poland reported hordenine in 2023 and 2026. PEA is not prescription-only and not a narcotic, and PEA itself is expressly exempted from the German New Psychoactive Substances Act. In sport, it is on the WADA list as phenethylamine along with its derivatives and is prohibited in competition. Hordenine is not named there; the US Anti-Doping Agency lists it as not prohibited, while the US collegiate sports association NCAA bans it.

Safety

There are no systematic safety data. In the only placebo study, headache, dizziness and malaise occurred. The combination with MAO inhibitors is critical: they markedly raise trace amines such as PEA, and these can increase blood pressure. One case report describes panic attacks and mood swings with selegiline ordered online plus PEA, another a brain hemorrhage after a kratom product contaminated with PEA. In animal experiments PEA is rewarding; rats self-administered it. PEA is not suitable when taking MAO inhibitors, antidepressants or stimulants, with high blood pressure, cardiac arrhythmias, anxiety or panic disorders, or during pregnancy and breastfeeding. Product quality is a risk of its own: the Dutch food authority found pharmacologically active substances, including PEA and hordenine, in 264 of 416 supplements tested.

Sources

• Borowsky et al., Proc Natl Acad Sci U S A 2001
• Rickli et al., Eur J Pharmacol 2019
• Sabelli et al., J Neuropsychiatry Clin Neurosci 1996
• Sabelli et al., J Clin Psychiatry 1986
• Szabo et al., Br J Sports Med 2001
• Lüthy and Schlatter, Z Lebensm Unters Forsch 1983
• Krombholz et al., Biomed Chromatogr 2022
• Sommer et al., J Agric Food Chem 2020 (hordenine)
• Biesterbos et al., Food Addit Contam 2019
• WADA, Prohibited List 2026