Encyclopedia4-fluoroamphetamine (4-FA)
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4-fluoroamphetamine (4-FA) - Encyclopedia

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4-fluoroamphetamine (4-FA)


What is 4-fluoroamphetamine?

4-fluoroamphetamine - also known as 4-FA, 4-fluor, 4-fmp, para-fluoroamphetamine or 4 fluoro-α-methyl-phenethylamine – is a research chemical of the amphetamine class. It’s mainly used as a party drug, as an alternative to MDMA and speed. 4-FA entered the recreational drug market around 2001, but its effects on humans have never been investigated scientifically. Users describe the effects as ‘more euphoric than speed and more stimulating than MDMA’. It most frequently comes in powder form or as a tablet. It’s mainly used orally and in rare cases, it’s snorted.


4-fluoroamphetamine was most likely first synthesized by Alexander Shulgin, who developed a wide range of substituted amphetamines of the phenethylamine type. The substance was first researched scientifically in 1975 on rats. There have never been studies into the effects on the human brain.

From 2001 on, 4-FA entered the market as a recreational drug. The designer drug is unscheduled in most countries. In the Netherlands, 4-FA doesn’t fall under the Opium Act, but it’s listed in the Medicines Act, which means you need a license in order to produce, order or sell it. However, it’s possible to purchase 4-FA online. In some European countries like Germany, Poland, Hungary, the United Kingdom and Slovakia, 4-FA is considered an illegal substance.



4-fluoramphetamine is both a releasing agent and a reuptake inhibitor of dopamine, serotonin and norepinephrine. It’s closely related to amphetamine; only the hydrogen atom on the 4th place of the phenyl ring is replaced by a fluorine atom.

It was found in rats that 4-FA reduced the activity of tryptophan hydroxylase and lowered the levels of serotonin and 5-hydroxyindoleacetic acid in the whole brain. Serotonin and 5-hydroxyindole acid levels only lowered for short times (2-6 hours) after drug injection and 5-hydroxyindole levels were essentially back to normal within 24 hours.


The following positive effects of 4-FA have been observed: it’s a stimulant that will give increased energy and euphoric feelings similar to MDMA. 4-FA elevates the mood, increases feelings of empathy and warmth, evokes a sense of openness and togetherness and may cause excessive talking. Furthermore, 4-FA enhances sensory perception, gives a body high and stimulates the lust to dance. Users report being completely immersed in music, also they feel more ‘in control’ when using 4-FA, compared to using MDMA.

Like other amphetamines, 4-FA causes stiff jaws and bruxism (grinding of teeth) in some users and it suppresses the appetite. Compared with other research chemicals the hyperthermic effect seems to be less severe, though overheating is still a possible risk. Furthermore, 4-FA increases the heart rate and may cause nausea, headaches and feelings of anxiety and discomfort. Insomnia is another possible side-effect of 4-FA.

Users report that the empathogenic effects are at their strongest during the first three hours after onset, whereas in the second part of the trip the stimulating effects prevail.


According to different sources, a dosage of 80-140 mg is considered common; a dose of 50-80 mg produces a mild trip.

4-FA usually comes as a white powder, sometimes in tablets, and it’s best taken orally; either as is or encapsulated in a piece of rolling paper or a capsule. It’s also possible to mix it with some water or fruit juice. 4-FA takes effect within 30 minutes to 1 hour. The whole experience usually takes about 6 hours, with a peak around 2-4 hours. Some users report trips of up to 12 hours.

It’s also possible to snort 4-FA, though this will damage the nasal mucosa and might hurt for up to 15 minutes. When snorted, less of the substance is needed and the effect will start within a couple of minutes. The effect will be shorter and more intense compared to taking orally.


As said before, no official research on 4-FA has been conducted with human beings. As with a lot of research chemicals, by taking them you’ll become your own guinea pig.

As 4-FA is closely related to speed (methamphetamine), you can expect the same health risks apply. This means you should never use 4-FA in combination with an MAOI. MAOIs are most commonly found in prescription drugs, like anti-depressants, but also in a range of natural products like Syrian rue (peganum harmala), banisteriopsis caapi, passionflower and yohimbe.

Individuals with heart disease (i.e. arteriosclerosis, hypertension) should also be extremely careful as amphetamines can be taxing on the heart.

Research shows that amphetamines used during pregnancy may decrease the birth weight of the baby as well as increase the likelihood of cardiac abnormalities (heart problems) and possibly other birth defects. Methamphetamine (speed) is believed to be transferred through breast milk, this might hold for 4-FA as well.

To our knowledge, no fatal incidents with 4-FA have occurred so far.


Not much is known about the long-term effects of 4-FA and even less about its interactions with other substances. In general different amphetamines (MDMA, speed) combine together well, though some users reported 4-FA suppresses the euphoric effects of MDMA.

Some people combine 4-FA with methylone (MDMC), another research chemical that’s closely related to MDMA. Both positive and negative experiences have been reported, though presumably, this combination is quite harmful to the brain, as the neurotoxicity of both substances adds up.

Alcohol in combination with amphetamines taxes the liver and kidneys, causing dehydration. This might lead to overheating and increases the bad side-effects.

Nothing is known about interaction with common psychoactive substances, though it’s clear that 4-FA should never be combined with MAOIs (see ‘Warning’).

Further reading/watching

-4-FA in Spuiten & Slikken (Dutch tv program)

-Erowid 4-fluoroamphetamine vault

-Legal status of 4-FA

-4-fluoramphetamine in rats: Fuller et al. Neuropharmacology, 1975.


-Erowid 4-fluoroamphetamine vault




-Drugsforum on research chemicals

-4-fluoramphetamine in rats: Neuropharmacology, 1975.

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