YOUNG people who smoke cannabis are twice as likely to suffer a stroke, experts have warned.
And heavy users of the drug are also at greater risk of potentially fatal heart problems, new findings show.
Two separate studies looked at the risks of regularly using marijuana.
The first showed those aged 18 to 24 who use the drug at least 10 days a month, have twice the risk of stroke - a clot or bleed that interrupts the blood flow to the brain.
Significantly, scientists at George Mason University in Fairfax, Virginia found that risk was in a group that did not smoke tobacco.
For those that do smoke as well, their risk of stroke was up to three times higher than those who never touched weed.
Lead author of that study, Tarang Parekh said: "Young cannabis users, especially those who use tobacco and have other risk factors for strokes, such as high blood pressure, should understand that they may be raising their risk of having a stroke at a young age."
“Physicians should ask patients if they use cannabis and counsel them about its potential stroke risk as part of regular doctor visits,” he told Fox News.
More research needed
The findings did not prove that cannabis was caused a person's stroke risk - but found a link.
They looked at the medical records of more than 43,000 people aged 18 to 24. Of them 14 per cent admitted to using cannabis in the previous month.
Parekh's team also found marijuana users were more likely to be heavy drinkers, which could also increase their stroke risk.
But the scientists did attempt to take that into account when making their conclusions, published in the American Heart Association's journal Stroke.
Parekh said more research is needed to understand exactly how the drug might be causing strokes.
Deadly heart problems
The second study, looked at the link between cannabis and the risk of heart arrhythmias - or irregular heart beats.
Scientists at the Griffin Memorial Hospital in Olkahoma, specifically studied patients diagnosed with cannabis use disorder.
The condition is defined as the frequent, compulsive use of marijuana - similar to an alcohol addiction.
The findings showed that people addicted to cannabis are 50 per cent more likely to be hospitalised due to an arrhythmia than people who never use the drug.
While some arrhythmias can be managed and do little damage, others can cause sudden cardiac death.
Atrial fibrillation is one of the most common arrhythmias, and is where the heart beats too fast and irregularly.
It's a common cause of stroke, meaning those with AF are five times more likely to suffer a bleed or clot in the brain.
Effects of cannabis hit in 15 minutes
Dr Rikinkumar Patel, from the hospital's department of psychiatry, said: "The effects of using cannabis are seen within 15 minutes and last for around three hours.
"At lower doses, it is linked to a rapid heartbeat.
"At higher doses, it is linked to a too-slow heartbeat.
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"As medical and recreational cannabis is legalised in many states, it is important to know the difference between therapeutic cannabis dosing for medical purposes and the consequences of cannabis abuse.
"We urgently need additional research to understand these issues."
Both studies were presented at the American Heart Association’s Scientific Sessions 2019.
The American Heart Association does not take a stance on the legalisation of marijuana, but calls for placing the use of cannabis in the same regulated space as tobacco in areas where it is legal to use.
Eleven states across the US have legalised the use of recreational cannabis, while another 33 states have given it the green light to be used as a medicine.
In the UK, the class B drug is illegal for recreational use, but medicinal cannabis became available on the NHS last year.
These findings come after another study, published yesterday, found daily cannabis use is "better at managing chronic pain than painkillers".