Dosage of Psychoactive Substances


The term overdose implies an accepted safe dose and safe use of PAS or medications.

With periodic use of psychoactive substances (PAS) in low or moderate doses, serious and life-threatening conditions are not common. The risks from psychoactive substance use largely depend on the substance, the dosage, frequency and mixing different PAS.

What is a dose?

The term dose refers to the ‘quantity of PAS or a medication introduced to the body in order to achieve optimal effects in most users.’ In terms of classification of dosage, there are several levels: microdose, threshold, light, common, strong, heavy and overdose (fatal or non-fatal). Each of these levels is distinguished with different intensification of the effects depending on the substance consumed.

In the context of recreational PAS use, understanding the doses and being careful regarding the quantity and manner of consumption is crucial to achieving a safe and pleasant experience. Consumption of a higher dosage can lead to negative experiences such as extreme anxiety, strong physical and psychological side effects, unpleasant psychedelic trips, hospitalization or (in extreme cases) death. On the other hand, with a very low dosage, a person might not feel the full effects, and that can lead to unpleasant feeling and frustration. This should not be disregarded since in such cases, a re-dose can result with sudden intense and potentially dangerous experience that is hard to control.

Classification of dosages and levels of effects

Although different substances can cause different effects regardless of the dosage and the intensity of the experience they are likely to induce, they can be divided in different levels.

A microdose is sub-perceptual dose which is so low that the chances for directly noticeable or perceivable effects are very remote.

A Threshold is a dose which will cause users to experience the effects of the substance in a subtle, barely perceptible manner or it will go completely unnoticed. This level borders the placebo effect and can be ignored with minimal effort, for instance by diverting the person’s attention to another activity. Users may vaguely sense “something” occurring on this level, but it is difficult to distinguish it from a placebo effect. Experienced users may be able to feel the threshold of the effect more easily.

A light dose will cause effects which are noticeable and clearly distinct from sobriety, but remain in the background of the user’s perception. The effects at this level can be ignored by increasing the focus and diverting the attention towards a task or activity. In order for the user to feel the effects, they need to focus their attention to recognize the effects. The user’s attention will not be completely directed towards the effects.

A common dose – the effects and the nature of the substance’s actions are quite clear and visible at this level, and ignoring the action would be difficult (although experienced users may be able to). The user will generally be able to participate in daily activities, will remain functional and communicable. The effects are dominant, but can be suppressed if the attention is directed to another activity.

A strong dose makes the user incapable of functioning as usual, of being in normal interaction with other people or thinking soberly. The effects of the drug are clear and in the forefront, the attention is focused on the action of the drug and is difficult to ignore. The user is completely engaged in the experience.

A heavy dose – the user has reached the upper limit or hit the ceiling of what this substance is capable of producing in terms of perceivable psychoactive effects. Depending on the substance consumed, the user might be incapable of functioning on the most basic level, and experience extremely uncomfortable adverse effects. It should be mentioned that in certain cases the dose can be harmful.

An overdose – the dose is greater than recommended or commonly consumed, and it might result in death or serious injury. In such cases, the immediate medical services should always be contacted. Experienced and regular users with tolerance might be able to survive such doses or avoid serious harm.

Defining the term OVERDOSE

Overdose means “use of PAS or medications in quantities or doses larger than recommended or commonly consumed.” An overdose is manifested as intoxication (toxic state or poisoning) or death.
The term overdose implies an accepted safe dose and safe consumption of PAS or medications. PAS or medication overdose may sometimes be caused by intentional suicide or self-harm, but often overdosing is accidental, the result of intentional or unintentional (ab)use of PAS or medications.

Consumption of illegal PAS with undetermined quality, in large quantities or after a period of abstinence can also lead to an overdose. Heroin users for instance, who inject easily, may inadvertently overdose because the line between a pleasant feeling and crossing the overdose margin is very close.

Most common reasons for PAS overdose 

The most common PAS or group of PAS listed as a reason for overdose or death are: opioids (heroin, methadone, morphine, tramadol, fentanyl etc.), alcohols (ethyl alcohol, methyl alcohol and ethylene glycol), sedatives/hypnotics (benzodiazepines, barbiturates , GBH and ketamine), psychostimulants (cocaine, amphetamines, methamphetamine, nicotine) or a mixture of several PAS with different effects.

The signs and symptoms of overdose depend on the type of PAS and the level of exposure. Symptoms are often divided in different toxidromes or forms and levels of intoxication (poisoning). The levels of intoxication can help recognize or reveal the type of PAS that caused the overdose.
Overdosing is a life-threatening condition and important to recognize. In cases of overdose suspicion, one should immediately call the emergency medical services. Below you will find the most common PAS overdose symptoms and treatment.

Opioid overdose (morphine, heroin, methadone, tramadol, fentanyl). The most common symptoms are: breathing problems: slow, shallow or stopped breathing, distinguishable snoring; loss of consciousness – the user may be unresponsive to outside stimulus, even if the stimulus is painful in normal circumstances (for instance, strong pinching or slapping); change of skin tone to bluish purple or grey, especially around the mouth or the extremities; nausea and vomiting – danger of suffocating, particularly if the person is unconscious or not safely turned on their side; slow heartbeat – weak or absent pulse; contracted pupils; epileptic seizures; muscle spasms – the body might be stiff and shaking in convulsion.

Treatment: Opioid overdose is treated with naloxone. Naloxone is not efficient in certain opioids like sufentanil. If no response is observed, the individual is administered additional doses not to exceed 10 mg, accompanied by assisted ventilation. When suspecting an overdose, turn the individual on their side and call the emergency medical services.

Psychostimulant overdose (cocaine, amphetamine, methamphetamine, MDMA, nicotine). The most common symptoms are: increased and irregular heartbeat; high blood pressure; disorientation; nausea and vomiting; anxiety – in certain cases extreme anxiety manifested with panic attacks; paranoia; delusions; involuntarily convulsions and shaking; increased breathing; pain during urination; increased body temperature; continuous involuntary movements – tics; epileptic seizures; psychosis; serotonin syndrome.

Psychostimulant overdose is treated with benzodiazepines in order to decrease the unpleasant anxiety and uneasiness. The body needs to be cooled in order to prevent hyperthermia and replace liquids with lots of water or isotonic drinks if the individual is conscious.

Alcohol overdose. The most common symptoms are: disorientation; nausea and vomiting; breathing problems; change of skin tone – purplish or greyish; impaired thermoregulation – low body temperature; loss of motor skills; loss of consciousness; dizziness; epileptic seizures.

Treatment: Talking with the individual in cases of anxiety. Prevent them from harming themselves. There is danger of suffocating if the individual is unconscious and cannot be turned to their side or sit up. If the state deteriorates or continues call the emergency medical services.

Synthetic cannabinoids overdose. Common symptoms: increased heartbeat; high blood pressure; nausea and vomiting; anxiety – often accompanied by panic attacks; feeling of impending doom; psychotic episodes; epileptic seizures; loss of control over motor skills.

Treatment: In cases of anxiety and uneasiness, reassure and calm the individual. If the person is unconscious, turn them to their side and call the emergency medical service.
Psychedelic substances such as LSD, hallucinogenic mushrooms etc. Consumed in wrong doses may create negative experiences or unpleasant mental state difficult to control, manifested with confusion, agitation, anxiety, panic attacks, unpleasant hallucinations, psychotic episodes or a feeling of constant hysteria.

Treatment: Talk to the person, reassure them they are safe, convince them everything will return to normal after the effects wear off. In cases of severe anxiety and agitation, use benzodiazepines to alleviate the side effects, and in cases of induced psychosis use antipsychotic medications.

Recommended dosage

Understanding dosages is crucial to safe and pleasant experience. With PAS use, it is best to avoid doses and levels unfamiliar to the user, i.e. ones that might create unpleasant feelings difficult to control. With inexperienced users, it is safest to begin with the lowest possible dosage in order to become familiarized with the nature and effects of the substance. This minimizes the risks of negative experiences. Heroism and large doses are very risky, particularly with young and inexperienced users.

Every individual reacts differently to each PAS, depending on factors such as: personal sensibility, tolerance, neuro-physiology, weight, metabolism, diet, rest, mood etc. An important factor to consider is the substance purity which always varies in different products. With some substances the full effect will begin after considerable time (sometimes even 2 to 4 hours), while negligent re-dosing carries risks.

Frequent use of certain PAS can lead to tolerance. The body becomes accustomed to the substance’s effects and requires increased dosages to achieve optimal effects. After frequent use and an interruption, it takes time for the tolerance to return to the normal levels. With most substances, the tolerance reduces in half in 3 to 7 days and returns to normal in 1 to 2 weeks.

Compulsive re-dosing (compulsory re-dosing) is described as the urge or desire to continuously re-dose a PAS in an attempt to increase or maintain the effect. The occurrence is most typical with alcohol use or stimulants which induce pleasant physical or emotional effects such as cognitive or physical euphoria. It can stress the side effects and unpleasantness, intensified with higher doses.

Davor Smilanov

The author is a doctor of medicine, graduated general medicine at the Faculty of Medicine within the St. Cyril and Methodius University in Skopje, Macedonia. Davor Smilanov, MD is the head of the Medical Service at the Harm Reduction Centre in Kapishtec within HOPS’s Harm Reduction Program. He has participated in numerous national and regional projects, conferences and campaigns on harm reduction.

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