What Does Weed Do to Your Body? Short- and Long-Term Effects, According to the CDC

What weed does to your body

Weed acts mainly through THC, which affects the parts of the brain that handle attention, coordination, decision-making, learning, memory and reaction time, while CBD doesn't get you high and is linked to many of the plant's therapeutic uses. In the short term that means the high, a faster heart rate and slower reflexes; with heavy, repeated use it can also affect memory, the lungs (if you smoke) and heart health. So is it harmful or therapeutic? That's the question every debate about cannabis keeps circling back to. 

Cannabis is one of the most widely used drugs in the world, alongside tobacco, alcohol and caffeine, and many countries have legalized it with its therapeutic potential in mind: it has anti-inflammatory properties, may ease chronic pain, works as a muscle relaxant and is often used by chemotherapy patients to ease the side effects of treatment.

The plant contains more than 100 compounds, and two stand out for their effects on the body: tetrahydrocannabinol (THC), the psychoactive one that alters normal brain function, and cannabidiol (CBD), which doesn't change how your mind works and is credited with many of the therapeutic benefits attributed to the plant. 

Still, it's not all sunshine and rainbows. Alongside the benefits most people recognize, there's no denying that repeated cannabis use comes with some downsides.

According to the CDC (the US Centers for Disease Control and Prevention), marijuana especially affects the parts of the brain responsible for attention, coordination, decision-making, learning, memory and reaction time. Some of these effects are short-term, kicking in right after you consume. Others can be long-term, the result of repeated use.

The negative effects of weed

A recent analysis covered by CNN pooled studies on more than 43,000 people and looked at how THC affects the brain's higher-level thinking. That matters because, on top of the functions above, the brain is also in charge of planning, organizing, solving problems and controlling emotions and behavior.

Along those lines, the researchers concluded that marijuana's impact on the brain could harm the cognitive development of young people, whose brains are still growing. In fact, according to the CDC, using before age 18 can affect how the brain builds the connections it needs for things like attention, memory and learning. 

Chronic marijuana use can also harm the lungs and heart. The respiratory system takes the biggest hit when you smoke, because cannabis smoke contains many of the same toxins, irritants and carcinogens as tobacco smoke.

The main risks of smoking weed are coughing, more phlegm and even bronchitis, although these symptoms usually improve once you quit. Smokers can also damage lung tissue and small blood vessels. That said, a lot more research is needed to pin down the specific effects of smoked marijuana.

Vaping might seem less harmful than smoking a joint, but it has its own respiratory costs: according to a 2021 study, people were almost twice as likely to report wheezing in the chest after vaping marijuana as after smoking cigarettes or using e-cigarettes.

As for the heart, marijuana use may raise the risk of heart disease and stroke. Right after smoking, your blood pressure and heart rate can also go up.

In short, heavy, repeated cannabis use has been linked to effects like these in some people: 

- Trouble concentrating.

- Reduced cognitive ability and mental performance.

- Loss of self-control and, in some cases, aggressive episodes.

- Drowsiness.

- Memory loss.

- Possible damage to brain cells (the evidence here is mixed).

- Psychotic episodes.

- Trouble adapting to social situations and relating to other people.

- Reduced psychomotor skills, which shows up as slow, clumsy movements.

- Low mood or depression.

- A faster heart rate.

- Anxiety.

Factors that shape how weed affects you 

The CDC notes that several personal factors influence how marijuana affects someone. These include how much and how often you use, and whether you mix it with other substances like alcohol or other drugs, which can raise the risk of harmful effects.

How you consume also matters a lot. The most common ways are smoking it in joints, blunts (rolled in cigar wraps) or bongs (water pipes), vaping it, or eating and drinking it in things like brownies or sodas. 

Two other factors come into play: your previous experience with cannabis or other drugs, and purely biological factors like genetics and sex. 

It may all sound negative, but medical cannabis is an essential tool for many patients dealing with a range of conditions. Our advice: see a doctor who specializes in cannabis or, if that's not an option, go slow and be careful when you start. 

We also strongly recommend steering clear of uncertified or sketchy cannabis oils and preparations sold on social media or the black market. It's very hard to know what's in them, and they can harm your health, since the one thing they often barely contain is actual cannabis. 

Do your homework and buy from trusted, safe sources. Responsible use is the way to go.

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