Side Effects of Marijuana

Medically reviewed by Alexander Tabibi, MD
August 15, 2020
pot side effects
pot side effects

Is it a feature or a bug? When it comes to understanding the side effects of marijuana it all comes down to perspective.

Side Effects of Marijuana

Like most other medicinal substances, whether you call it weed, cannabis or medical marijuana – there are both positive side effects – which is why we use the treatment and negative side effects – which can be anything from an annoyance or a hindrance all the way to potentially significant dangers. Also one persons side effect may be what another person seeks. It’s always important to always remember that the effects of cannabis can be highly affected by the biology of the individual (not to mention what other drugs – legal or illegal are being used at the same time).

So let’s start with the relatively……

Minor Side Effects of Marijuana


How many people do you know that say. If it weren’t for the fact that I would with 1000 lbs I would smoke more. Well there’s a simple reason for that. One of the main and most well known side effects of cannabis is the munchies. THC is a potent activator of the brain in areas that drive the perception of hunger. This is a side effect many people rather not have but for cancer or AIDS patients amongst others this is the effect they are searching for to drive the hunger that the patients do not feel as a result of the disease, chemotherapy and even depression.


No matter the route of administration cannabis can also make you feel tired or lethargic and some people hate this feeling. It can also therefore add to the dangers of driving. Again on the other hand some people use weed specifically for this reason and some people therefore used cannabis – whether one with THC or CBD varieties to help in relaxation and sleep. Recreational users have been using marijuana to chill, or relax, so while it’s not necessarily a side effect, it’s definitely a standard expectation for most strains

Dry Mouth

Cotton mouth. Yuck. This one of the generalized side effects of cannabis. People used to blame the smoke when that was the major form of administration – but it occurs even with vaping or gummies. THC reduces the production of saliva in the mouth by the attachment of THC to cannabinoid receptors on the salivary glands. The higher the level of THC – the more likely one is to get dry mouth. Remedies include chewing gum, sipping water or a lollipop and other things that promote saliva production. 

Red Eyes

There’s a reason that eye drops are the best friend of many a weed consumer trying to hide their recent consumption. Many users suffer from the red and dry eyes marijuana causes. The reason is simply that the vessels in the eyes dilate to counteract the reduced blood pressure caused by the marijuana. So the eyes appear bloodshot.

Brain Effects

We are mostly self aware when we use marijuana that some of the side effects include difficulties with memory, reactivity, attention, response times and emotions. 


We’ve all at least known a friend – if not seen a movie where the person using the THC can have from mild to severe anxiety. and sometimes even panic attacks. Other people can have more disturbing levels of paranoia – again associated with often very high levels of THC.

Cough/Upper respiratory effects

Coughing is pretty frequent with smoking or even vaping weed. While the good news is that there seems to be no increase in lung cancer in cannabis smokers – even with heavier use – the coughing fits are a problem for many – in particular if they smoke more, use more potent strains and e.g hold their breath for longer. So yes, coughing is considered one of the side effects. 

As many as 25% of habitual smokers develop a chronic cough with wheezing and phlegm production.  (Note that shortness of breath is absent and if present could be indicative of another potentially major medical problem and medical advice should be sought). As long as not accompanied by tobacco use the respiratory effects described do dissipate with time and a reduction in the frequency of smoking and the potency of the cannabis.

Major Side Effects of Marijuana


The BIG worry. One thing that many people worry about is whether they will develop a dependence on marijuana. The data appears to suggest that the earlier you start to smoke – the higher the chances that you will develop a dependency on weed. This means that for those starting consumption of cannabis earlier than 18 years of age – about 16% become dependent whereas for those starting later that number decreases to about 10%.


Another BIG worry.

While we know that users can experience paranoia from cannabis associated with the THC – there is a more serious issue – that is a  psychotic break with reality which can occur with especially high potency strains. A European study indicates that up to 20 % of newly diagnosed cases across 11 hospitals across Europe were associated with cannabis consumption with the risk of being diagnosed as psychotic has a threefold increase in those who use weed on a daily basis. They warn in particular of the more potent marijuana varieties which are ever more present as increasingly potent varietals are created and/or enhanced by additional infusion of THC in some cases.

Brain development in young users

In addition to early age usage having a higher rate of dependency there is another significant danger in consumption of cannabis. Basically the younger the person is the more time they have that their brain is developing into an adult brain. So teens are very vulnerable and children are even more so. We even know that the cannabis consumed by pregnant mothers can lead to behavioral problems in their children as well as issues with attention, memory and analysis. This is one of the side effects you should pay particular attention to when considering using while pregnant or around children, or as one of the direct side effects that children and teens are especially vulnerable to.


Everyone reacts to medications and supplements differently, so it’s important to be open and honest with your healthcare professional to determine any risk or sensitivities to side effects that you should be aware of. THC content varies by strain and could contribute to reactions, as could your mood or underlying conditions. Take it slow and be alert. But understand that side effects of marijuana vary by person, and by what your goal is. One person’s negative side effect of marijuana is another person’s objective.