AMPHETAMINES: CHARACTERISTICS AND SIDE EFFECTS - NEUROPSYCHOLOGY - 2026

The amphetamines are substances that perform a stimulating action on the central nervous system. Despite being popularly known as illegal drugs and harmful both physically and mentally, they are also legal drugs with beneficial properties.

The main difference lies in the composition of the drug and in the consumption that is carried out, since amphetamine drugs must be ingested under strict medical supervision. Although they are consumed as a medicine and not as a drug of abuse, these substances can produce a series of side effects on the body.

In the therapeutic field, amphetamine is used to synthesize drugs such as Fenproprex or Clobenzorex that increase brain stimulation. In contrast, in the field of drugs of abuse, amphetamine is used to synthesize addictive substances such as methamphetamine (Speed).

In amphetamine drugs, the stimulant potential is much greater, hallucinogenic effects are produced and clearly addictive components appear.

Forms of consumption and mechanism of action

D-amphetamine

In general, all amphetamine drugs (for therapeutic use and for recreational use) are administered orally, developing their effects in about 30 minutes.

However, in some cases, especially drugs of abuse, the drug can also be administered parenterally (injected), a fact that allows a greater hallucinogenic effect of the compound.

The main peculiarity of this drug is that its distribution in the body is total, it easily crosses the blood-brain barrier and, despite its molecular size, it enters the brain very easily.

Normally, these substances have a multiple effect in the brain, which is why many neurotransmitters are involved with amphetamine use.

Mechanism of action of amphetamines.

Thus, both dopamine and serotonin, adrenaline or norepinephrine see their functioning modified when amphetamine enters the brain, so the effects that this drug can cause are very varied.

This fact explains, in part, that the same substance can be used both as a therapeutic measure and for addictive and recreational use, since a controlled action can provide brain benefits, but an excessively high action can lead to a clear addiction and various psychological alterations.

Amphetamine usually increases the release of dopamine in the brain, inhibits serotonin reuptake, and alters the actions of adrenaline and norepinephrine.

Effects of amphetamines

The most common side effects of amphetamines are: nervousness, difficulty sleeping, uncontrollable fear, headache, changes in sex drive, dry mouth, constipation or diarrhea, loss of appetite, weight loss, and addiction.

Amphetamines are stimulant substances of the central nervous system, so when consuming these substances there is usually an increase in brain activity.

Thus, while the use of other drugs such as cannabis or alcohol can inhibit or slow down some activities of the brain, amphetamine is mainly characterized by exciting and stimulating this region of the body.

This fact is translated into the appearance of symptoms after the consumption of methamphetamine, such as aggressive and violent behavior, increased energy and motor activity, the feeling of well-being or increased security and confidence.

Likewise, methamphetamine use tends to decrease sleep and fatigue, increase the speed of thought and speech, suppress the sensation of appetite, increase blood pressure and heart rate, and increase body temperature.

Amphetamine is a substance that can be used to synthesize designer drugs that achieve these pleasant effects and an increase in energy and excitement.

Here are the symptoms of amphetamine use:

Nervousness

Amphetamine produces a general stimulation of the central nervous system so this extra increase in excitement can translate, in some cases, into sensations and feelings of nervousness.

This is probably one of the most discussed side effects when using this substance to treat ADHD problems.

Children who suffer from this psychological alteration suffer from attention deficits, which is why the consumption of amphetamines is very suitable to increase the concentration capacity of these children.

However, amphetamine also overexcites the body, so it can increase anxiety and nervousness in the person, making it not suitable for children with high hyperactivity.

Difficulty falling or staying asleep

Another of the most typical side effects of amphetamines is difficulty falling asleep and staying asleep. The reason for this effect is the same as the previous one, that is, the overstimulation that these substances produce on brain function.

Consuming amphetamine implies that brain functions are increased and are more excited than normal, so if the doses administered are not adapted to the characteristics of the person they can cause insomnia with relative ease.

In these cases, the stimulation that is sought to increase attentional processes and the ability to concentrate makes the brain stay awake when it has to relax, making falling asleep more difficult.

In the same way, once you have fallen asleep the brain can continue to perform excessive activity, so early awakenings can also appear.

Uncontrollable shaking of any part of your body

Although the therapeutic objective of drugs composed of amphetamines is to control the effect only in certain regions of the brain, it is quite complicated.

As we have seen, amphetamine is a substance that is easily dispersed throughout the brain regions, so despite the fact that the greatest effects are performed in the areas where the therapeutic effect is sought, amphetamine has effects in other parts of the brain.

While amphetamine acts on the cerebral cortex or higher structures of the brain, it may also have effects, albeit minor, in lower brain regions, while it is beneficial for increasing attention and concentration.

Many of these regions known as subcortical, since they are located below the cortex, control the movements of the body, so if amphetamine acts excessively in these areas of the brain it can cause tremors in different parts of the body.

Headache

Like any substance that we introduce into our brain, amphetamine can cause headaches and discomfort in this region of the body.

In general, the inappropriate use of amphetamines, that is, the consumption of methamphetamines, produces a consistent headache within hours of use (in the same way that alcohol or other drugs can cause it).

With regard to amphetamine drugs, headaches are usually less frequent and less intense but they can also appear in some cases.

Changes in sexual drive or ability

Sexual impulses, desires and processes have their beginning in the brain and in the functioning of different brain regions. In particular, sexual behavior is linked to the action of serotonin, a substance that is present in multiple parts of the brain.

As we have seen, amphetamine modulates the activity of serotonin by inhibiting the reuptake of this neurotransmitter from the brain.

Thus, while the action of amphetamine tries to achieve other effects through the modulation of serotonin, such as increasing well-being or improving attention span (functions that this neurotransmitter also performs), it can also cause negative effects such as alterations sexual.

Feeling of dry mouth

The effects produced by amphetamine are not limited to the mental component, but also modify the physical functioning of the body. When the brain is "overstimulated" by this substance, it stops performing other actions such as preparing the body for ingestion.

This fact can produce many symptoms, but one of the most typical is the sensation of dryness in the mouth, in a way very similar to that which appears when we have anxiety.

Constipation or diarrhea

Another alteration that amphetamine consumption can produce is digestive dysregulation. In this way, constipation, diarrhea or other digestive conditions may appear.

This fact could be explained because in the same way that amphetamine modulates cognitive activities (such as the ability to concentrate) or psychological (such as the feeling of well-being), it also modulates parts of the brain destined to carry out basic functioning processes such as digestion.

Loss of appetite

Loss of appetite is one of the main symptoms of amphetamines, to the point that these substances are sometimes used to treat problems related to drinking or being overweight.

This fact, as with sexual alterations, is explained in large part by the action of serotonin in our body.

Amphetamine acts mainly on this substance since it is closely related to attentional processes and other cognitive activities, thus allowing the drug to provide therapeutic benefits.

However, serotonin performs other actions such as balancing sexual desire, regulating appetite through satiety or controlling body temperature.

In this way, when consuming amphetamines the function of this neurotransmitter is altered and, despite the fact that the greater effects it produces are beneficial, it is often difficult to control these negative effects that we comment on.

Weightloss

This symptom is closely linked to the previous one since when amphetamine produces a constant loss of appetite, weight loss comes progressively.

In these cases it is very important to go to the doctor since, unless the drug is being consumed with the aim of losing weight, if the appetite is reduced excessively, the dose and amphetamine treatment must be restored.

Addiction

Finally, the last symptom that we will discuss is the addictive capacity of amphetamine. Even if it is in small amounts and through consumption strictly monitored by a doctor, amphetamine has a high addictive component.

This action is carried out mainly through dopamine, a neurotransmitter that is much more affected in amphetamines for recreational use, since the compositions of these drugs seek to produce an addiction in the consumer.

In amphetamines for medical use, the addictive component is much more controlled and attempts are made to minimize rather than maximize, however dopamine continues to be slightly altered, so its use can create addiction.

Therapeutic uses

However, amphetamine also has therapeutic uses, since this substance allows to stimulate the central nervous system and improve wakefulness, attentional processes and the ability to concentrate.

The controlled and therapeutic use of amphetamines allows to increase the higher cognitive functions (attention and memory) and to improve the executive functions of the person.

Likewise, amphetamines in their therapeutic use also have reinforcing effects, since they produce pleasant emotions and reinforce the systems involved in the regulation of specific emotional responses: it reduces impulsivity and increases self-control.

On the other hand, as these substances decrease appetite, the consumption of amphetamines in very controlled amounts can be useful to treat eating disorders and being overweight.

However, despite the controlled use of these substances, the consumption of amphetamines can cause side effects, so the use of these drugs must be very careful.

References

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3. Goodman and Gilman (1996) The pharmacological bases of therapeutics. Ed by Hardman, JG; Limbird, LE 8th edition. Inter-American McGraw-Hill. Mexico.

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