How Does Cannabis Effect The Human Body? | CAC
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Did you know that 10.5% of adults use cannabis purely for medical reasons, and 46.6% use it both medicinally and recreationally1? This statistic highlights cannabis’s significant role in both health and leisure today.

Cannabis has evolved from an ancient remedy to a modern medical aid, now widely used in healthcare globally. For instance, experts endorse using oral cannabinoids to alleviate chemotherapy-induced nausea. Additionally, cannabis has proven effective in pain reduction and short-term relief of muscle spasticity in multiple sclerosis patients.

Medical cannabis has been legal in the UK since the 1st November, 2018. The uptake has been a little slow, but a recent push for more research and education in cannabis has seen a shift in societal attitudes towards the plant.

While cannabis is becoming more accepted for its medicinal properties, it is also gaining popularity as a recreational substance. With the legalization of recreational use in Canada, Germany, Thailand, and some states in the US, there has been an increase in demand for products such as edibles and oils. This trend is expected to continue as more countries consider legalising recreational use.

cannabis effects human body

Key Takeaways

  • A significant portion of adult cannabis users turn to the plant for medical purposes.
  • Cannabis holds a long history of medicinal use, deeply rooted in ancient practices.
  • Short-term oral cannabinoid treatment effectively alleviates MS-related spasticity symptoms.
  • 28 states and the District of Columbia have legalised medical cannabis use, highlighting shifting political landscapes.
  • Clinical trials and current research hint at a promising future for targeted cannabinoids in treating various conditions.

Introduction to Cannabis

Cannabis, scientifically known as Cannabis Sativa, has been used for both medicinal and recreational purposes for centuries. Its journey from ancient healing practices to modern medical applications has been marked by significant changes, including its status as a controlled substance. In the 1990s in the USA, laws began to emerge allowing medical cannabis use, transforming public perception and directing scientific inquiry. Today, 28 states and the District of Columbia permit cannabis for medical treatment2.

The primary compounds in cannabis are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is known for its psychoactive effects, while CBD is researched for its potential health benefits without inducing a high. A pivotal study by Lindgren et al. in 1981 shed light on THC’s effects in the body, advancing our understanding of cannabis3.

These compounds interact with the endocannabinoid system, which regulates various bodily functions. The National Academies’ report on cannabis use discusses its health implications based on current research.

The legalisation of recreational cannabis in eight states and D.C. signifies changing public attitudes and increased research interest in cannabis and its effects on the human body.

cannabis effects human body

How Cannabis is Consumed

Cannabis can be consumed in various ways, each offering a different experience. Smoking is common but harmful, releasing toxic chemicals like ammonia and hydrogen cyanide that damage the lungs, leading to coughing and respiratory issues. Combining cannabis with tobacco exacerbates these problems4.

Vaping is a modern alternative, heating cannabis to release THC without the harmful byproducts of combustion. However, the long-term health effects of vaping remain debated.

Edibles, such as gummies or cookies, provide another consumption method. They produce slower, longer-lasting effects as the liver metabolises THC, enhancing its potency, requiring cautious dosing to avoid overconsumption.

Cannabis comes in various forms, including skunk and oils, each with unique effects and consumption methods, allowing users to choose what suits them best.

As of March 2021, over 36 states and the District of Columbia have legalised cannabis, reflecting a significant shift in societal and legal perspectives in the USA. This ongoing change, driven by new laws and technologies, influences global cannabis use, underscoring the importance of understanding its health and legal impacts.

Cannabis in the Body

The interaction between cannabis and the body is complex, involving the absorption and metabolism of its active compounds. Once ingested, THC and CBD affect brain cells, influencing cognition, memory, and learning for up to a day. THC increases dopamine levels, altering sensory perception, time awareness, appetite, and mood5.

Approximately 1 in 10 cannabis users may develop dependency, with higher risks for adolescents (1 in 6). Heavy users may require increased pain medication and face surgical complications. Frequent adolescent use can impact brain development, potentially reducing cognitive abilities by age 386.

The structure of cannabis compounds affects their absorption and longevity in the body. Excessive smoking can impair lung function and weaken the immune system due to THC’s immunosuppressive and irritant properties. Understanding cannabis’s physiological impact is crucial for comprehending its effects.

Smoking or vaping cannabis accelerates heart rate and reddens the eyes, potentially exacerbating respiratory issues like asthma7. Mental effects include impaired decision-making, hallucinations, and addiction risks, highlighting cannabis’s profound impact on brain function.

cannabis Effects on the Body

Short-Term Effects on the Body

Cannabis’s short-term effects can be enjoyable, inducing happiness and relaxation while altering sensory perception. However, short-term use poses risks, impairing cognitive and motor functions, crucial for tasks requiring clear thinking. Some users may experience anxiety, paranoia, or hallucinations, influenced by individual mood, environment, and cannabis potency6.

The consumption method affects cannabis’s onset and duration. Smoking or vaping provides immediate effects, impacting coordination and attention. Research indicates that cannabis can increase heart rate by 20-50 beats per minute, adding cardiovascular stress.

Cannabis can impair memory and learning, particularly in individuals under 25 whose brains are still developing. Awareness of these short-term effects is vital for responsible cannabis use7.

Long-Term Effects on Physical Health

Long-term cannabis use presents a mix of risks and benefits. Prolonged use can lead to chronic respiratory issues and lung damage, especially in individuals with pre-existing conditions like asthma.

Cannabis’s impact on cognitive function is significant, particularly for young users. It can impair memory and learning abilities, exacerbated by the increasing potency of modern cannabis strains8.

Mental health risks include potential links to schizophrenia, depression, and anxiety, particularly in individuals with a family history of these conditions. Daily use during adolescence heightens these risks.

For pregnant or breastfeeding women, cannabis poses developmental risks to the child’s brain. THC can pass into breast milk, affecting the baby.

Long-term cannabis use may also cause cannabinoid hyperemesis syndrome, leading to severe nausea and vomiting7. There is also a potential increased risk of testicular cancer in young male users.

The effects of long-term cannabis use depend on usage patterns, frequency, age, and dosage, emphasizing the need for informed consumption guidelines.

Impact on the Central Nervous System

Cannabis’s effects on the central nervous system (CNS) are primarily due to THC and other cannabinoids. THC increases dopamine levels, creating a high, with approximately 30% of users potentially developing addiction. The CNS contains numerous CB1 receptors, influencing brain function and communication.

Cannabinoids may benefit certain neurological conditions, such as neurodegenerative diseases, pain, and anxiety, by modulating receptor activity9. This potential has driven research into cannabinoids as treatments for epilepsy and multiple sclerosis.

However, cannabis use can impair memory and learning, particularly in individuals under 25. Long-term inhalation may increase stroke risk and exacerbate mental illnesses like schizophrenia due to high CB1 receptor concentrations in certain brain regions.

Understanding how cannabis chemicals affect the CNS is crucial for harnessing its medicinal benefits while mitigating risks. Ongoing research into cannabinoid-brain interactions will aid in developing safe, effective treatments.

cannabis Effects on the Body

Mental Health Implications

The relationship between cannabis and mental health is complex. While cannabis does not directly cause depression, anxiety, or PTSD, it can exacerbate certain mental health issues. Frequent cannabis use is linked to higher rates of social anxiety, indicating a potential risk of increased anxiety from cannabis consumption.

Daily cannabis use can worsen symptoms in individuals with bipolar disorder and is associated with increased suicidal ideation. Understanding cannabis’s impact on mood and mental health is crucial, especially given the high prevalence of co-occurring mental health and substance use disorders.

Research by Marconi et al. found that heavy cannabis use increases the risk of hallucinations and delusions, with heavy users being almost four times more likely to experience these symptoms compared to non-users. This challenges the notion of cannabis as a safe substance and highlights its controversial mental health effects.

Younger users are particularly vulnerable to cannabis’s effects on mental health due to ongoing brain development. Continued research is essential to fully understand cannabis’s mental health implications and to develop strategies to protect young people from potential harm11.


As we conclude our comprehensive exploration of cannabis, we see its multifaceted impact on health. Cannabis has proven benefits, such as alleviating chemotherapy side effects, pain, and MS symptoms, highlighting its potential in medicine.

However, cannabis use also poses risks, including respiratory issues and mental health concerns. Some studies suggest that cannabis could reduce opioid use in pain patients, though it may not be suitable for conditions like dementia12. More research is needed to fully understand these effects.

Moving forward, we must integrate existing knowledge and advocate for further research into both the benefits and risks of cannabis13. This approach will help us navigate evolving legal landscapes and potentially relaxed cannabis regulations. By fostering informed policies and education, we can maximise cannabis’s benefits while minimising its harms, ensuring a safe and effective use of this versatile plant.

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