Cannabis is bad for the heart and may trigger heart attacks and strokes, doctors have warned.
The American Heart Association (AHA), who reviewed the available evidence, now recommend avoiding cannabis to protect the heart.
In a scientific statement, it said smoking cannabis has some of the same harms as tobacco, which is known to be a leading cause of death worldwide.
Research has shown the recreational drug may have health benefits — but smoking cannabis has been linked with a slew of damaging heart problems.
Chemicals inside the drug can cause heart rhythm abnormalities within an hour of smoking, studies show.
The toxins can alter blood pressure, heart rate and trigger inflammation, all of which are underlying culprits of heart disease and strokes.
The AHA warning applied to people who use the drug recreationally, as well as and for medicinal purposes.
Cannabis is bad for the heart and may trigger heart attacks and strokes, doctors have warned
Study author Professor Robert Page, from the University of Colorado, said the review found cannabis has ‘the potential to interfere with prescribed medications’.
He added studies have also suggested it may ‘trigger cardiovascular conditions or events, such as heart attacks and strokes’.
Professor Page also warned attitudes towards cannabis have changed rapidly’, with US states and countries legalising it for medical or recreational use.
He added: ‘Health care professionals need a greater understanding of the health implications of cannabis.’
Professor Page and AHA colleagues examined existing research on the connection between cannabis and the heart.
Their findings were published in the AHA journal Circulation.
Dr Rose Marie Robertson, the deputy chief science and medical officer for the AHA, said: ‘The AHA recommends that people not smoke or vape any substance, including cannabis products, because of the potential harm to the heart, lungs and blood vessels.’
The statement said the a full understanding of how use of cannabis affects the heart and blood vessels is limited by a lack of adequate research.
THE DIFFERENCES BETWEEN THC AND CBD
Tetrahydrocannabinol (THC) and cannabidiol (CBD) are both derived from the cannabis plant.
Together, they are part of the cannabinoid group of compounds found in hashish, hash oil, and most strains of marijuana.
THC is the psychoactive compound responsible for the euphoric, ‘high’ feeling often associated with marijuana.
THC interacts with CB1 receptors in the central nervous system and brain and creates the sensations of euphoria and anxiety.
CBD does not fit these receptors well, and actually decreases the effects of THC, and is not psychoactive.
CBD is thought to help reduce anxiety and inflammation.
The debate around marijuana and its claimed medicinal properties is rife.
But the AHA applied their statement against cannabis to people who use it for both recreational and medicinal purposes.
It added: ‘Cannabis may have therapeutic benefits, but few are cardiovascular in nature.’
Medical marijuana is legal in 33 US states and Washington, DC, where it is prescribed for pain management, anxiety and depression.
Washington DC, as well as 11 other US states, have already legalised recreational cannabis use.
Only people with specific conditions are able to get cannabis-based medicine with THC in it in the UK. However, it is difficult to get a prescription.
The most common chemicals in cannabis include THC, the component of the plant that give a ‘high’, and CBD, which does not produce a ‘high’ or intoxication.
Existing studies have found that within an hour after cannabis is smoked, THC may cause heart rhythm abnormalities.
These include tachycardia, premature ventricular contractions, atrial fibrillation and ventricular arrythmias.
THC also appears to stimulate the sympathetic nervous system, which is responsible for the ‘flight or fight’ response.
It can result in a higher heart rate, greater demand for oxygen from the heart, higher blood pressure while laying down and dysfunction within the walls of the arteries.
On the other hand, studies on CBD found links with reduced heart rate, lower blood pressure, increased vasodilation which helps arteries to open up, lower blood pressure and potentially reduced inflammation.
It’s for these same reasons that people chose to use CBD products with the aim of reducing anxiety, depression, chronic pain conditions and more.
CANNABIS: WHAT ARE THE BENEFITS AND DRAWBACKS?
Cannabis is an illegal Class B drug in the UK, meaning possession could result in a five year prison sentence and those who supply the drug face up to 14 years in jail.
However, the drug is still widely used for recreational purposes and can make users feel relaxed and happy.
But smoking it – the most common way to consume the drug – can also lead to feelings of panic, anxiety or paranoia.
Scientific studies have shown the drug can alleviate depression, anxiety and stress, but heavy use may worsen depression in the long term by reducing the brain’s ability to let go of bad memories.
It can also contribute to mental health problems among people who already have them, or increase users’ risk of psychosis or schizophrenia, according to research.
Marijuana can be prescribed for medical uses in more than half of US states, where it is used to combat anxiety, aggression and sleeping problems. Researchers are also looking into whether it could help people with autism,eczema or psoriasis.
Cannabis oil containing the psychoactive chemical THC, which is illegal in the UK, is claimed to have cancer-fighting properties, and a host of patients claim to have recovered from the disease by taking the drug.
Cannabis-based medicine with THC in it was legalised in the UK in November 2018. However, it is difficult to get a prescription.
Very few people in England are likely to get a prescription for medical cannabis. Currently, it is only likely to be prescribed for children and adults with rare, severe forms of epilepsy, and adults with vomiting or nausea caused by chemotherapy.
Studies have shown cannabis-based medicine could halve the number of seizures suffered by children with a rare type of epilepsy called Dravet syndrome.
Inflammation is an underlying culprit of the narrowing of the arteries that can lead to heart disease and strokes.
Therefore, CBD alone may be beneficial — but the AHA did not say this.
Smoking and inhaling cannabis, regardless of THC content, has been linked with a number of heart problems.
Cardiomyopathy, or heart muscle dysfunction, angina, or chest pain, heart attacks, heart rhythm disturbances, sudden cardiac death and other serious cardiovascular conditions have all been discussed in the scientific literature.
Professor Page said: ‘Many consumers and health care professionals don’t realise that cannabis smoke contains components similar to tobacco smoke.’
Smoking and inhaling cannabis, regardless of THC content, has been shown to increase blood concentrations of carbon monoxide, a poisonous gas, five-fold.
And tar, partly burnt combustible matter, increases three-fold, similar to the effects of inhaling a tobacco cigarette.
Chest pain, heart attacks, heart rhythm disturbances and other serious heart conditions are associated with carbon monoxide intoxication, the statement said, whether from tobacco or cannabis.
For anyone with existing heart disease, risks go up.
Smoking cannabis has triggered heart attacks, a higher risk of strokes and heart failure in people with underlying heart disease, studies show.
The review also found cannabis has the potential to interfere with prescribed medications, therefore the AHA urged for a better understanding of the risks among doctors.
Some studies suggest cannabis use, both CBD and THC, may be safe and effective for older populations.
Older adults, although the least likely to use cannabis, often use it to reduce neuropathic pain, improve quality of life and decrease prescription drug use such as opioids.
And it’s been reported cannabis can have benefits for patients with age-related diseases, including Parkinson and Alzheimer disease.
Some two million Americans with heart disease currently use marijuana or have used it in the past, according to a recent report in the Journal of the American College of Cardiology.
But concern about them using the drug include the potential of how it could interact with other medications including blood thinners, anti-depressants, antipsychotics and statins.
Existing studies on marijuana and the heart are short-term, observational and retrospective studies. This means they can spot a trend, but cannot say for certain there is cause and effect.
There is an ‘urgent’ need for ‘carefully designed, prospective short- and long-term studies regarding cannabis use and cardiovascular safety,’ Professor Page said.
However, this could be challenging given that marijuana is classified as a Schedule I drug by the US Drug Enforcement Agency (DEA), which limits scientists from studying it.
Professor Page said anyone planning to use marijuana should discuss possible risks with their health professional first.
But if people do choose to use cannabis for whatever reason, it is vital they only use legal cannabis products.