Long- and Short-Term Health Effects of Marijuana

Marijuana is one of the most commonly used addictive substances in the United States, trailing alcohol and tobacco.¹ There are many harmful short- and long-term effects marijuana may cause on the brain and body.

This article will explore the effects and dangers of using marijuana and provide information on treatment for marijuana addiction.

What Are the Short Term Effects of Marijuana (Weed)?

Some of the short-term effects of marijuana include:¹

• Altered sensory perception, such as seeing brighter colors.
• Altered sense of time passing.
• Increased heart rate.
• Mood changes.
• Impeded body movement.
• Difficulty thinking clearly or using problem-solving skills.
• Problems with memory recall.

When taken in excessively high doses, some of the short-term effects of marijuana use can include:¹

• Hallucinations.
• Delusions.
• Psychosis.

Long-Term Effects of Marijuana on the Brain

Marijuana use may also have negative long-term effects on someone’s brain, including impaired memory, and reduced cognitive development (when used during adolescence), and is associated with mental health problems like addiction, depression, and anxiety.¹

The following sections will explore the long-term effects of weed on the brain and mental health in more detail.

Does Marijuana Cause Memory Loss?

Marijuana use is proven to cause memory impairment in the short term, meaning it can cause memory loss within the 24-hour period when it is used.² However, there is also some evidence that using marijuana during childhood or adolescence may cause lasting memory loss and other problems.¹

Research suggests that marijuana use when someone’s brain is still developing may cause long-term alterations in brain functioning in domains like attention, memory, or learning.² It is unclear whether these changes are permanent or if these impairments will dissipate over time, as the long-term effects of marijuana on the brain are still being studied.³

Does Marijuana Cause Brain Damage?

Studies on animals have led researchers to believe that marijuana may damage the brain in several key areas of functioning over time, such as impulsivity and risk-taking behaviors.⁴ These studies show alterations in the functioning of the hippocampus, an area of the brain that controls executive function and memory.⁴

Assertions on the long-term effects of marijuana on the human brain are supported by some studies that found a decline in performance on IQ testing associated with long-term marijuana use in adolescents. However, other studies have not found marijuana use to cause a decline in IQ scores.³

How Does Weed Impact Mental Health?

Marijuana use can impact someone’s mental health over time, especially when used frequently or in large amounts.⁵

Marijuana use has been linked to increased symptoms and occurrences of:⁵

• Depression.
• Anxiety. 
• Suicidal ideation.

Depending on the dosage used and how often someone uses marijuana, they may also be at an increased risk of developing more severe mental health problems such as temporary psychosis or lasting schizophrenia.⁵

Marijuana is also addictive. Between 9% and 30% of all people who begin using marijuana develop a marijuana use disorder (the clinical term for marijuana addiction). The likelihood of developing marijuana addiction is higher among people who began using the drug before age 18.¹

Long-Term Effects of Marijuana on the Body

There are several ways that marijuana impacts the body over time. Marijuana use has a wide range of effects on the various systems of the body, as well as the potential to cause harm to a developing fetus when cannabis is used during pregnancy.¹

The following sections will discuss the long-term effects of marijuana use on the heart, lungs, and the potential harm caused by smoking pot during pregnancy.

Effects of Marijuana (Weed) on the Lungs

When marijuana is inhaled, such as by smoking through a pipe, a joint, or other methods, it can irritate the lungs.¹ Marijuana smoke contains many of the same toxins and irritants as tobacco smoke,⁶ and people who smoke marijuana regularly can develop the same respiratory problems as people who smoke tobacco.¹ The long-term effects of marijuana may include:^1,6

• Frequent cough.
• Increased phlegm or mucus production.
• More frequent respiratory illnesses like bronchitis.
• Increased risk of lung infections.

More research is needed on the effects of smoking marijuana and how it affects the respiratory system and chronic respiratory illnesses like lung cancer, emphysema, or chronic pulmonary obstructive disease (COPD).⁶ At this time, research does not indicate a higher risk of lung cancer among people who smoke marijuana.¹

Effects of Weed on the Heart

Researchers believe chronic, prolonged marijuana use can put someone at heightened risk of stroke, heart attack, and other vascular diseases due to the way marijuana use temporarily raises heart rate and blood pressure.⁷

Older people or people with pre-existing heart conditions may be at an increased risk of cardiovascular issues from marijuana use.¹ Research is still needed to understand the effects of the irritants found in marijuana smoke on the cardiovascular system and if they can increase the risk of death.⁷

Smoking Weed While Pregnant

One study reported by the National Institute on Drug Abuse found that 20% of pregnant women ages 24 and under tested positive for marijuana.¹ Criticism of the same study suggests that these numbers are underreported, meaning that marijuana use in pregnancy is likely more common than previously thought.¹

Marijuana use during pregnancy has been linked to lower birth weight and increased risk of unusual neurological development in newborns.^1,8 Research indicates that the chemicals in marijuana, including tetrahydrocannabinol (THC)—the psychoactive chemical in cannabis—can pass through a pregnant person’s system and impede the development of the fetus.⁸ In particular, studies suggest that marijuana exposure during pregnancy can lead to problems with attention, memory, problem-solving skills, and behavioral issues for the child as they grow up.⁸

After the baby is born, some of the chemicals in marijuana can be passed from parent to child through breastfeeding.⁸ Because THC is stored in body fat, there is a chance THC may be passed to the newborn through breastfeeding weeks after someone quits. However, more research is needed to prove or disprove this claim.⁸

How Do Different Forms of Weed Affect the Brain and Body?

Marijuana can be used in a variety of different ways, and marijuana potency and how fast it takes effect can vary depending on how it is prepared.⁹

Marijuana flowers are typically smoked, cooked into food, or brewed into tea.¹ When smoking marijuana, THC reaches the bloodstream and causes effects to be felt quickly. When marijuana is consumed orally, most people feel the effects within 30 to 60 minutes.¹  “Edibles” (marijuana products that are eaten rather than smoked) often take more time to have an effect and it can be difficult to judge how high they will make someone.¹ This raises the likelihood of experiencing immediate dangers and may increase the risk of developing a marijuana addiction.¹

Additionally, there are many new ways of processing or concentrating marijuana that can raise the potency of weed. These methods can make the cannabis produce a stronger feeling of intoxication.⁹

Common ways of processing or concentrating marijuana include:⁹

• Dry and dry ice processing.
• Water-based processing.
• Using a combination of pressure and heat.
• Using nonflammable solvents like carbon dioxide or flammable solvents like butane.

Solvent-based products tend to be more potent, measuring between 54-80% THC levels, compared to regular marijuana which tends to measure between 39% and 60% THC.⁹

High-potency forms of marijuana are more likely to cause negative health effects and risks because it is difficult to judge the dosage used when large amounts of THC are consumed in a single breath.⁹ Using high-concentration marijuana products also puts someone at a higher risk of developing a marijuana use disorder.⁹

It is also worth noting that residual amounts of contaminants like butane may be present in highly concentrated forms of marijuana.⁹ Research shows someone that who uses these products likely inhales at least trace amounts of contaminants, which can have harmful effects on the body as well.⁹

Can You Reverse Damage from Smoking Marijuana?

It is unclear at this time whether the damage caused by smoking marijuana is fully irreversible; however, several studies have yielded encouraging results.

One study of adolescents suggests that memory improved progressively with abstinence from marijuana. This finding is consistent with previous research as well.¹⁰ Unfortunately, the same study found that attention did not improve among the adolescents studied within the study period.¹⁰

A study measuring the physical health effects of abstinence from marijuana found improvements in lung function over time, demonstrated by a reduction in cough, sputum production, and wheezing.¹¹

Marijuana Addiction and Abuse Treatment

Fortunately, marijuana addiction is a treatable condition. Treatment for marijuana use disorder can include behavioral therapy, peer support, and other modalities.¹²

Our staff is available 24/7 at to help you begin the admissions process at our drug addiction treatment center in Las Vegas. Our helpful admissions navigators can also answer questions about using insurance to cover rehab expenses or help you find other ways to pay for rehab.

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