Important update 1-09-2016:

The Trimbos institute issued a press release concerning the risks of the usage of 4-FA (4-fmp). They stated that the risks of 4-FA are bigger than previously thought. Think off physical complaints as (tremendous) headache, but also cardiovascular problems and strokes.

Here is our message.

Update 9 september

On the 13th of october, the Coördinatiepunt Assessment and Monitoring ‘new drugs’ get together to inform about the 4-FA related incidents. They will advise the ministry of Public Health about  legality of 4-FA.

Video Trimbos-instituut:

What is 4-FA / 4-FMP?

4-Fluoroamphetamine, often called 4-FA, is a novel psychoactive substance (NPS) that belongs to the chemical group known as the phenethylamines, which also includes MDMA (ecstasy) and amphetamine (speed). Other names for 4-FA are flux, fifa, 4-fluo, 4-FMP, 4-F, 4-flava, 4-flo and 4-fluor.

Disclaimer on NPS

The information provided here is based on users’ experiences and on tentative data from research institutes that study NPS. No comprehensive studies have been done on the shorter- or longer-term effects of 4-FA. Hence, if you take 4-FA, you are your own guinea pig. So it’s important to be extra careful.

Mode of use

4-FA is usually taken orally, either in tablet or in powder form; it is also available in liquid form. Powdered 4-FA is often packed into a capsule or a rolling paper (a ‘bomb’). It may also be dissolved in a drink. Sniffing is not common; that causes an intense, burning pain in your nose.

Unity tip: Weigh out powdered 4-FA carefully beforehand. Use a scale that can measure milligrams precisely. 


These are some dosages reported by users who took 4-FA orally:

Low:                              50–70 mg
Moderate:                    70–110 mg
High:                            115–150 mg

or sniffed:                     50–75 mg

Both users and experts advise against dosages of more than 150 mg. The effects may be overpowering, the chances of side-effects increase above 100 mg, and the risk of dangerous effects such as severe overheating increases sharply at doses above 150 mg.

Unity tip: People that are oversensitive to 4-FA may also encounter problems with lower doses. If you are taking 4-FA for the first time, take a low dosage to see how your body responds.

The amount of 4-FA in tablets, capsules and powders can vary greatly. The 4-FA could also be laced with other substances, but you can’t tell that by the way a tablet, capsule or powder looks.

Unity tip: Always have your drugs tested. Check unity.nl/testing for addresses, opening hours and requirements.

Side-effects of topping up

If you spread your dosage over the day or evening, a particularly common side-effect is sleep disturbance (even two nights running). Topping up often fails to deliver the stronger effects you are looking for. Negative side-effects may be greatly aggravated, however.

Effects of 4-FA

How you will experience the effects of 4-FA depends on three things:

  1. Set − Who you are, what you’re expecting and how you’re feeling
  2. Setting − Whether you’re at a lively party or in the quiet of your home
  3. Drug − What drug(s) you’re taking and how much of them

Most users say the effects of 4-FA lie somewhere between those of speed and ecstasy. The effects are more euphoric than those of speed and more energising than those of ecstasy. They are often perceived as steadier than the effects of ecstasy. The following effects have been reported by users or have been identified in research:

Positive effects 

  • energetic feelings
  • euphoric, amorous feelings
  • strong feelings of connectedness
  • desire for contact, conversation and intimacy
  • more intense experience of physical contact and music
  • urge to dance

Negative effects

  • forgetfulness
  • confusion and restlessness
  • anxiety, paranoia and delusions (e.g. the idea that people are talking about you)
  • diminished appetite and dry mouth
  • elevated body temperature
  • elevated blood pressure and heart rate
  • difficulty urinating
  • tense muscles and jaws (biting your tongue or cheek)
  • difficulties sleeping (especially after a top-up dose)
  • nausea, vomiting
  • sweating
  • difficulty reading
  • irritated feeling and short-temperedness
  • heart palpitations
  • severe headaches

The first effects of 4-FA are noticed after 20 to 60 minutes, sometimes longer. You feel tingling sensations and a warm glow comes over you. The effects last 4 to 6 hours. Some people still feel effects for up to 12 hours after taking 4-FA. If you sniff it, the effects start within minutes and wear off faster.

The ‘Tuesday blues’

Some users of 4-FA experience a crash or downer in the days that follow. They may feel depressed, unhappy, listless, oversensitive and empty. The downer is usually at its worst on day 2 or 3 after you take 4-FA. Although some users say the comedown is milder than the one they experience after ecstasy use, many of them nonetheless report fatigue and moodiness for several days. It is unclear what the exact cause of the 4-FA downer is. High doses, combined use of 4-FA with ecstasy, and frenetic exercise and dancing in combination with a lack of sufficient food and sleep, are probably the chief factors. 

Unity tip: Eat healthy food before, during and after 4-FA use and get plenty of rest. Don’t take 4-FA if you are very tired or are suffering from insomnia. Be sure to consume enough antioxidants, minerals and vitamins from fruits and vegetables.

Short-term risks

Our risk information derives largely from users’ reports, research knowledge about the risks of comparable drugs, and data from Dutch drug checking services (DIMS) and the monitoring system for drug-related emergencies (MDI). The risk of serious problems depends on the composition of the drug(s) taken and the sensitivity, health and behaviour of the user. The surrounding environment is also a factor. How many and what beverages are consumed? How much exercise does the user get? How hot is it? Has the user taken different drugs together?


Everybody is different and everybody reacts differently to drugs. Some people experience adverse effects from low doses, whilst other, less sensitive people don’t feel any effects at all from that same dose. Severe, and sometimes fatal, acute reactions are not predictable and are not always dose-related.

Severe acute risks are

  • cardiovascular problems
  • brain haemorrhages
  • overheating (hyperthermia)

Other acute risks are severe/excruciating headaches, lockjaw, unconsciousness, and severe confusion, whereby extreme agitation can lead to a life-threatening overload of the heart muscle (excited delirium).

Cardiovascular problems

4-FA causes increases in blood pressure and heart rate. Potentially that may result in brain haemorrhaging, irregular heart rhythm, heart failure and pulmonary oedema. There are indications that cardiovascular problems are relatively frequent in 4-FA use. That is an additional reason to be cautious if you already know you have this type of problems. Have you suffered a headache during or after the use of 4-FA? Then we advise you not to take it again.

Brain haemorrhage

Symptoms of brain haemorrhaging are

  • severe headache
  • confused speech
  • slurred speech
  • drooping mouth
  • neurological deficits (e.g. paralysis in arm)

If you or one of your friends exhibits such symptoms, go to a hospital emergency department immediately or phone the emergency number 112.


Overheating is a serious short-term risk. If you take 4-FA, your body may no longer be able to regulate its temperature, and it warms up. If you then get vigorous exercise or find yourself in a hot or humid area, your body temperature can become dangerously high.

That is indicated by the following symptoms:

  • skin feeling too warm
  • flushed or pale face
  • headache
  • confusion
  • stiff muscles
  • dizziness
  • shakiness
  • racing heartbeat
  • nausea, vomiting
  • reduced state of consciousness

Unity tip: Take a rest break every hour. Don’t wear warm clothes and don’t wear a head covering while indoors.

Emergency department (A & E)

Do you feel unwell? Or has one of your friends become unwell? Don’t wait. Go to the emergency department immediately. If there is no emergency department nearby, phone 112. Be honest about what drugs and drinks have been consumed. The medical staff are there to help you. Never leave a person alone who feels unwell. 

Long-term risks

The more 4-FA you take and the more often you take it, the greater the risk of negative long-term effects. Because 4-FA is a rather new drug, no long-term risks have been documented as of yet. On the basis of what is now known, some potential risks are

  • greater vulnerability to cardiovascular problems
  • serious fatigue and insomnia
  • weakened physical condition and resistance
  • psychological problems: depression, anxiety, deep discontentment, poor concentration
  • brain injury
  • psychological dependency: partying is no fun any more without 4-FA

Combined use

Combining different substances carries extra risks. It produces unpredictable effects and there is a greater risk of health problems. Little is currently known about the effects of combining 4-FA with other psychoactive substances.

Speed and/or ecstasy in combination with 4-FA

4-FA is a stimulant drug, which can cause cardiovascular problems. That risk is aggravated if you combine 4-FA with other stimulants like speed or ecstasy. Effects may reinforce one another, and because the effects of 4-FA persist relatively long, there is a greater risk of unpleasant side-effects like ‘jacked up’ behaviour, stiff jaws, tense muscles, heart palpitations, pressure on the chest, sleep disturbances, and wicked hangovers and crashes

Alcohol in combination

Alcohol subdues the effects of 4-FA and blurs your limits. You may get the urge to take extra 4-FA or to drink more alcohol. Alcohol also heightens the chances of headaches and nausea.

GHB in combination

Some people take GHB to temper the stimulant effects of 4-FA. The anaesthetic effects of GHB may then get camouflaged by the stimulant effects of 4-FA, increasing the risk of a GHB overdose.

Unity tip: Don’t take 4-FA if you have diabetes, heart problems, blood pressure problems or psychological problems. Also avoid 4-FA if you are pregnant, suffer from migraines or epilepsy, or are taking medicines.

The law

On May 25th 2017 4-FA was placed on Schedule I (the list of hard drugs) of the Opium Act. This means it has been classed as an illegal drug and possession, trade and production of 4-FA is illegal.

It is against the law to take part in road traffic whilst under the influence of drugs. It is also dangerous, both to you and to other road users. Clubs, raves and festivals have zero-tolerance policies in place. Because police and security workers cannot recognise what drugs you are carrying, you may be refused entry or even handed over to police if you are caught in possession of 4-FA. 

Taking 4-FA is never without risk! By carefully reading the information and advice in this leaflet and heeding the tips provided by Unity, you can limit the side-effects and health risks of the use of 4-FA as much as possible.