While the toxicity of cannabis is very low, and that no one has ever died as a direct and immediate consequence of recreational or medical use of cannabis, it is still wrong to say it is an entirely harmless substance.
Smoking any drug is unhealthy, and cannabis is no exception. Cannabis smoke actually contains higher concentrations of carcinogenic polycyclic aromatic hydrocarbons (PAHs) than tobacco smoke. Cannabis smokers generally inhale more smoke for longer, depositing more than 4 times as much tar in their lungs as those who smoke cigarettes. To balance this, they smoke fewer joints and smoke less often.
Combining cannabis and tobacco is even worse. If you are a heavy smoker of cannabis and tobacco joints (more than 10 a day), you are significantly increasing your risk of developing lung disease. Recent studies show that the greatest pre-cancerous abnormalities appear in those who smoke the two drugs together.
Another important factor is that most cannabis smokers stop when they reach their 30s. Long term surveys of cigarette smokers showed that those who stop before the age of 35 had only a very slightly increased risk of lung cancer. The same may apply to cannabis.
Other Lung Problems for Pot Smokers
A pot smoker also has other lung issues they need to worry about when they inhale this substance. The person will have similar health problems to someone who uses tobacco exclusively, such as chronic coughing and an increased level of phlegm production. Regular marijuana use also increases the risk of chest illnesses and lung infections. These respiratory issues may mean that a pot smoker is more likely than someone who smokes tobacco to take time off from work.
Heart Issues and Marijuana Use
Lighting up a joint of Mary Jane and taking a toke has an immediate effect on the user's heart. Using the drug causes the individual's heart rate to increase between 20 and 100 percent. The elevated heart rate may last for as long as three hours.
The higher heart rate creates a strain on the weed smoker's heart. As the heart beats more rapidly, the individual may experience cardiac arrhythmia (an abnormal heart rhythm). The risk of heart attack increases in the first hour after using marijuana. People who are older or who have a heart condition are especially at risk for a myocardial infarction.
It may be tempting to think of the risk of heart attack as something that only applies to middle-aged people who are overweight or who otherwise don't take good care of themselves, but this is not necessarily the case. A heart attack can happen to people who don't have a known history of cardiac issues, and the fact that using pot can increase the risk of this outcome is nothing to discount.
Challenges in Daily Living
With regular, heavy use, some pot smokers may experience an impairment in their cognitive abilities. The ability to understand what they have read is affected, along with the marijuana user's verbal and mathematical skills. Students who get high before going to class are not going to be able to retain the lessons they are being taught.
Tasks that require a high degree of concentration are challenging for someone who has been using Mary Jane. Coordination is affected, and driving or operating machinery becomes more difficult.
With regular use, the person becomes unmotivated. They may also be more likely to be late for or absent from school or work. Consequences of being absent on the job may lead to disciplinary action, up to and including dismissal.
A higher than usual turnover rate for employment is not the only consequence of using weed that individuals need be concerned about; marijuana users are more likely be involved in accidents and to make a claim for Workers' Compensation benefits.
A common side-effect, usually for first time or early users, is anxiety, panic, paranoia and feelings of impending doom. However, these effects disappear within hours. Reassurance and a supportive environment also help.
There are also anecdotal reports of long-term users 'turning a corner' in their cannabis use, where they can no longer enjoy the experience as cannabis triggers paranoia and anxiety attacks.
In a recent study, between 10%-15% of people who smoked cannabis reported "paranoid" or "confused" feelings as a disadvantage of smoking cannabis. And over 27% reported "anxiety" as a regular or occasional effect. Around 30% gave "negative experiences" as their reason for permanently quitting cannabis.
There is general agreement that heavy cannabis use can precipitate schizophrenic episodes in those with the disorder, but there is no evidence that it can cause the underlying psychotic disorder. Heavy cannabis users can exhibit long-lasting toxic psychosis involving delusions and hallucinations that can be incorrectly - and dangerously - diagnosed as a schizophrenic illness.
In some cases, a person with mental health issues will turn to marijuana as a way to self-medicate. Rather than providing effective treatment for the underlying issue, the pot use only serves to mask the symptoms. Even if the individual consulted with a healthcare professional to get treatment, the drug use makes it more challenging to do so effectively.
If you have mental health problems, taking a drug - any drug - excessively is going to make your problems worse. Help is available for people who want to stop using marijuana and have been unable to quit on their own. They can go for marijuana detox first, then check into a marijuana rehab, which are staffed by trained professionals with the expertise to understand the issue and offer solutions that will work for you.