Pain is defined as an unpleasant feeling that is conveyed to the brain by sensory nerves. Discomfort signals usually represent an alarm of disease and the symptom announces that something is not right with our bodies.

Unfortunately, pain causes are not always understood and treatment can be challenging. Thus, the search for new and better pain relievers continues.

Marijuana’s pain-relieving properties have been described widely and its analgesic features has been used to popularise the use of medical, as well as recreational marijuana.

Marijuana which is also known as cannabis, is a complex plant. Even though cannabis has been used and cultivated by mankind for at least 6,000 years, our current knowledge on its pharmacological properties is based on more recent studies.

The two most known compounds of the plant are cannabidiol and delta-9-tetrahydrocannabinol; CBD and THC were isolated in 1963 and 1964 respectively.

The discovery of these compounds has led to the further discovery of the important endocannabinoid human system.

This system’s receptors are widely distributed in the human brain and body, which are considered to be responsible for numerous functions.

These functions normally respond to endocannabinoids (cannabis type of substances normally produced by the human body).

The functions of the endocannabinoid system are altered by the intake of external substances, including the cannabis plant, even in its natural form as a herb.

CBD and THC have different effects in our systems and act like two different drugs. CBD does not induce intoxication and diminishes the psychotropic effects of THC; it causes a decrease in blood pressure and heart rate.

In contrast, THC causes euphoria and an increase in blood pressure and heart rate. This last compound is responsible for psychotropic effects (“the high”).

Traditionally, cannabis has been consumed and prepared from the plant.

The cannabis plant has two main subspecies, cannabis indica and cannabis sativa.

They can be differentiated by their different physical characteristics. Indica-dominant strains are short plants with broad, dark green leaves and have higher cannabidiol content than the sativa plants in which THC content is higher.

Sativa-dominant strains are usually taller and have thin leaves with a pale green colour. Due to its higher THC content, C sativa is the preferred choice by recreational users. In the plant, cannabinoids are synthesised and accumulated as cannabinoid acids, but when the herbal product is dried, stored and heated, the acids decarboxylate gradually into their proper forms, such as CBD or d-9-THC.

Pharmaceutical cannabis preparations offer users the opportunity to control the CBD/ THC ratios as well as quantities.

This new feature makes cannabis a welcome new alternative for physicians to treat uncomfortable symptoms and chronic illnesses.

As physicians, we are familiar with learning new drugs and titrating prescriptions to effect and to individual tolerability.

Nevertheless, there has been a recent and consistent worldwide increase in cannabis potency in all of these formulations, with increasing associated health concerns.

It is no longer rare to see acute cannabis intoxications in the emergency rooms located at jurisdictions where cannabis is more available.

Cannabis has a wide range of effects that may vary between light and heavy users and can include feelings of intoxication, euphoria, altered sensory perception, cognitive and perceptual distortions, anxiety, dizziness, and increased appetite.

In terms of cognitive processes, there is extensive evidence that acute cannabis exposure impairs attentional tasks, consolidation and retrieval of memory, learning and executive functions.

Additionally, studies have found cannabis exposure related to disinhibition and impaired decision-making.

Chronic cannabis use can also lead to what is called a motivational syndrome, which is characterised by apathy, lack of motivation and poor educational performance.

Acute cannabis intoxication in healthy young people causes slower reaction times, impaired accuracy and impaired response inhibition

One of the main adverse effects of cannabis is the development of use disorder, characterised by a strong desire to use cannabis, using larger amounts than intended, and continued usage, despite negative social and physical consequences, craving, tolerance and withdrawal.

It is my opinion that physicians are best qualified to prescribe medical cannabis in the same way we manage other medications, like other pain killers.

Current cannabis formulations are appealing to medical use.

That was not the case in 2010. While working as a pain medicine fellow at Massachusetts General Hospital, I was puzzled by some medical marijuana prescribing methods (for example, brownies containing an undisclosed amount of CBD/ THC).

It is important to make a clear distinction between medical and recreational cannabis.

Recreational use of cannabis is not risk-free. Regulations for its use should be similar to alcohol and tobacco.

Users must be old enough to understand the risks that cannabis use may represent to their physical and mental health.

Providers must warranty the quality and hygiene in the production line.

Below, a few facts to keep in mind when you decide to use cannabis for recreation:

• Cannabis is the most commonly used psychoactive substance. In 2016, 13.9 per cent of users were 12 years and older.

• Rates of cannabis use in the United States are higher in young adult men with low incomes and no college education than among other population groups.

• Approximately one in eight current regular cannabis users develop cannabis use disorder.

• Cannabis use before age 17 years is strongly associated with lower educational attainment and increased use of other drugs, but these associations are not clearly causal.

• Individuals with cannabis use or cannabis use disorder often use other psychoactive substances, especially alcohol and tobacco. Substantial bidirectional comorbidity is seen between cannabis use disorder, schizophrenia, and several other psychiatric disorders, including depression, bipolar disorder (mania), anxiety disorders and antisocial personality disorder.

• Cannabis acutely impairs attention, concentration, episodic memory, associative learning, and motor co-ordination in a dose-dependent manner. Long-term cannabis use is associated with impairment of verbal memory and cognitive processing speed, which resolves after at least a month of abstinence.

• Substantial evidence suggests that chronic cannabis use, especially during adolescence, is associated with later development of schizophrenia.

• Cannabis use is associated with injury and death from motor vehicle accidents.

• Cannabis smoking is associated with acute, transient respiratory symptoms, but chronic use is not associated with impaired lung function.

• Cannabis smoking acutely increases sympathetic activity and myocardial oxygen demand, and is associated with a small increased risk of myocardial infarction and stroke.

• Cannabis use is also associated with periodontal disease, hyperemesis syndrome and a lower sperm count.

• Gorekick et al June 2020. Cannabis use and disorder: Epidemiology, comorbidity, health consequences, and medico-legal status. Literature review • Annie Pinto is American Board-certified anaesthesiologist and pain medicine specialist and is a member of Patients 1st health advocacy group