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Effects of THC (Marijuana)

THC interferes with the way the brain normally communicates, creating a variety of effects, notably elevating a person’s heart rate, reducing their inhibitions, and often giving them a sense of relaxed euphoria. THC, the psychoactive chemical in marijuana, can affect a person’s brain by acting on certain structures of the brain due to its similarities to the naturally occurring brain chemical anandamide.

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What Does It Mean to ‘Get High’?

Marijuana is often associated with the phrase “getting high,” although the term broadly applies to the use of most recreational drugs. To “get high” is to use a drug and then feel its effects. The term was originally applied to the euphoric effects of alcohol, although slang has evolved such that we don’t generally use the term in reference to alcohol use anymore. 

The main psychoactive ingredient in marijuana is THC. When a person smokes or vapes a substance containing THC, it passes from the lungs into the bloodstream. When smoked, a person generally gets high within a few minutes. If someone instead eats a product containing THC (edibles), the full effect of the drug will take longer to manifest, usually taking somewhere between 30 to 60 minutes to set in. 

Smoked marijuana, the most common way THC is absorbed, will create a noticeable effect on a person’s body and mind for about one to three hours, with edibles lasting much longer.

Duration of THC Effects

Researchers say THC can stay in the body for days or even weeks after you use it. However, most people who use marijuana don’t feel the impact of the drug for this long.

When you’ll notice changes and how long they last depend on the method of marijuana you choose:

  • If you inhale marijuana: You’ll feel the effects within seconds, and the changes can last up to 24 hours.
  • If you ingest marijuana: You’ll feel the effects within 30 to 120 minutes, and you can feel the changes for up to 24 hours.

THC’s Effects on the Body

As the body absorbs THC, a person may notice a number of changes occurring. Common effects of marijuana use include the following:

  • Drowsiness or sedation
  • Bloodshot eyes
  • Augmented heart rate
  • Increased blood pressure
  • Bigger appetite
  • Coughing due to lung irritation

Extended use can suppress a person’s immune system, increasing their risk of infection. 

A person can also grow dependent on marijuana, with their body undergoing withdrawal if they cease taking the drug. However, marijuana withdrawal is generally mild, with symptoms including the following:

  • Irritability
  • Insomnia
  • Decreased appetite

Smoking marijuana is an efficient way to deliver THC to brain cells, but it’s not safe. Researchers say marijuana smoke can include the same toxins found in cigarettes and other tobacco products. There’s some evidence that frequent marijuana smokers have a higher risk of testicular cancer too.

Pregnant people should not use marijuana, as it may affect the development of their child, increasing the risk of certain cognitive problems. Some evidence has also suggested THC can be excreted in breast milk.

THC’s Effects on Mental Health

THC works directly on brain cells. The impact people feel is directly related to the following factors:

  • The age people were when they started drug use
  • The dose taken
  • The duration of use
  • The potency of the drug
  • Genetic and biological differences

In the short term, THC can cause disorientation, unpleasant thoughts, and feelings of anxiety. Some people also develop temporary psychosis.

In the long term, marijuana has been associated with significant problems like schizophrenia, depression, social anxiety, and higher suicide risks.

Marijuana use has been linked to affecting brain development in young people. At least one study showed heavy marijuana use in a person’s teens, where significant brain development is still taking place, may reduce a person’s IQ by an average of 8 points. This change was not seen in people who began smoking weed as adults.

Researchers warn that modern marijuana products come with high THC content. These drugs might cause more significant mental health problems than their weaker counterparts.

Is Marijuana Dangerous?

Research about marijuana is complicated and always changing. Some studies haven’t found a link between marijuana use and an early death, while others found the opposite.

The Centers for Disease Control and Prevention suggests that marijuana can impact people in the following ways:

  • Cancer: Smoking marijuana can deliver cancer-causing chemicals into the lungs and cardiovascular system.
  • Heart: Marijuana can raise blood pressure and make the heart beat faster.
  • Lungs: Smoked marijuana can lead to coughing, mucus production, and bronchitis.
  • Mental health: Regular users are more likely to develop psychosis.
  • Brain: Marijuana can impact portions of the brain that deal with memory, learning, and decision-making.

Some chronic marijuana users also develop cannabinoid hyperemesis syndrome, which causes a person to experience cycles of severe nausea that sometimes require medical attention due to dehydration.

Does THC Have Legitimate Medical Uses?

The official stance of the DEA is that marijuana is a Schedule I substance, marking it as dangerous and with no accepted medical use. They have a less harsh stance on THC specifically, which has approved uses for products that can help with nausea and vomiting in cancer patients and to stimulate the appetite of AIDS patients. 

THC solutions can also help in the treatment of anorexia, working as an alternative antiemetic treatment. In addition, an oral solution containing a small amount of THC can be used to treat certain epilepsy conditions

Many people believe THC, and marijuana in general, has more legitimate medical uses that can be discovered through research. One of the most notable is its potential to help control chronic pain, for which several states sanction its use. 

Updated March 25, 2024
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