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What are the Physiological Effects of Marijuana?

Cannabis users know that smoking or ingesting marijuana makes you feel good. People wouldn’t use it if it didn’t provide a pleasurable sensation, and leave them feeling happier overall. But why does smoking a joint or eating a hash brownie make us feel like that? And what are the physiological effects of marijuana that you can’t see?

Originally posted 11th July 2016, Updated on 15th January 2019

Why does marijuana make you feel good?

Marijuana is full of a compound called Tetrahydrocannabinol, or THC. When THC reaches the brain cells, those cells release dopamine, the “feel good” chemical. This chemical makes everything seem better, from your mood to commonplace things such as eating. A study published in the Cold Spring Harbor Perspectives in Medicine journal backs up this theory.

The physiological effects

Other than just making you feel good, marijuana has a number of other physiological effects including:

    • Balance and coordination are thrown off. THC can interfere with the cerebellum and basal ganglia areas of the brain. These are responsible for things such as balance, coordination, and reaction time, which is why users might sometimes find they have difficulty with speaking, walking, and driving. A study done in 2016 found that marijuana caused significant cognitive motor deficits in those that used it.
    • While marijuana use can actually help reduce these feelings in many cases, those with certain genetics may be predisposed to feeling anxious after using marijuana, according to the National Institute on Drug Abuse.
    • Sleep deprevationSleep deprivation. THC has been proven to interfere with the most important REM stage of sleep. This of course can cause people to have a lack of focus and concentration, and extreme fatigue throughout the day after using marijuana. A study published in the Journal of Addictive Diseases found that frequent marijuana users (those that used it once a day or more) had higher scores on the Insomnia Severity Index.
    • Heart rate increases. According to the National Institute on Drug Abuse, a person’s heart rate can increase by 20 to 50 beats per minute after smoking marijuana. When other drugs are taken along with marijuana, the heart rate can even double. After about 20 minutes, the heart rate goes back to normal.
    • Blood vessels in the eye expand. Red eye is a tell-tale sign that someone has used marijuana, and this is the precise reason why, as found in this study published in Neuropharmacology.
    • Dry mouth. Excessive thirst or dry mouth is another side effect because cannabinoid receptors are located in our mouths, and they’re the same receptors responsible for saliva production. When these receptors are activated by cannabis, they can no longer create saliva, leaving that feeling of a mouthful of cotton balls. According to The Open Neurology Journal, dry mouth is one of the most frequent side effects of using marijuana.
    • The munchies. Not all cannabis users will experience the munchies and some Harold and Kumar get the munchieseven claim it is a stereotype. It is true however, that THC activates the hypothalamus portion of the brain over and over (think of a button being pushed) and this is the area of the brain that’s responsible for signalling things such as hunger. This was proven in a 2105 study done on mice, and published in the International Journal of Science, which can be found here.


It’s true that the “feel good” feeling is one of the first physiological effects you’ll feel after using marijuana. However, there are also a number of other physiological effects that explain why users might act and feel the way they do after smoking a joint.

MSNL Team / 15th January 2019

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