Smoking cannabis can affect the body in many ways. It can provide pain relief and a feeling of calm, but also increase lung irritation, impair memory and judgment, and cause eye redness.

Many effects of smoking cannabis are short term, meaning that they last for only a short period. Other effects are long-term and may not show up immediately.

There is not much research into the effects of secondhand cannabis smoke. It is possible that secondhand smoke exposure may be enough to cause some of the temporary effects, as well as some of the long-term effects, in some people. More research is necessary to examine the effects of secondhand cannabis smoke.

The following article discusses some of the potential benefits and side effects that smoking cannabis has on the body.

Often, a person will smoke cannabis to feel its effects. However, a person could also:

  • vape it
  • cook it into food
  • use it as part of an oil
  • brew it with teas
  • use other topical or oral cannabis products

Many of the negative effects of smoking cannabis are related to the method of use rather than the drug itself. Using another delivery method, such as edible formats, to use cannabis may help to reduce the potential risks associated with smoking cannabis.

Cannabis use can have a wide range of effects on the body. These effects can also vary depending on the way a person uses cannabis. For example, many side effects can occur as a result of smoking, and not necessarily from using cannabis itself.

Some of the most common effects on physical health from smoking cannabis use include:

  • a higher likelihood of developing bronchitis, when a person smokes it
  • more phlegm, when a person smokes it
  • lung irritation from irritants including some carcinogens, such as accidentally burning the mouth or throat when smoking
  • a weakened immune system due to the effects of tetrahydrocannabinol, which is the main psychoactive chemical in cannabis
  • pain relief
  • reduction in vomiting and nausea
  • faster heart rate
  • red eyes from the increase in blood flow
  • relief from the symptoms of glaucoma, for short periods
  • aggravation of existing lung conditions, such as asthma, when a person smokes it
  • potential interference with tumor growth
  • interference with fetal development during pregnancy
  • interference with brain development among teenagers

When people use it medically, cannabis is often useful for the following:

  • reducing pain associated with certain medical conditions, such as multiple sclerosis
  • reducing inflammation
  • helping with glaucoma
  • reducing nausea in people undergoing chemotherapy
  • epilepsy in children
  • cancer-related anorexia
  • lessening tremors in certain conditions, such as Parkinson’s disease
  • post traumatic stress disorder (PTSD)

Some of the most common effects a person may experience include:

  • increased appetite and thirst
  • increased or decreased depression symptoms, depending on the user
  • increased or decreased anxiety symptoms, depending on the user
  • impaired judgment, making it harder for people to think clearly
  • problems with short-term memory
  • the release of dopamine, which causes the feeling of being high
  • symptoms of withdrawal after long-term use
  • delayed reactions to stimuli
  • temporary paranoia and hallucinations
  • addiction, in some cases

Cannabis has many potential psychological effects, and it is worth noting that this is not a comprehensive list.

Cannabis is only potentially safe for use by adults.

Children and teenagers are susceptible to potential ill effects. When a pregnant person uses cannabis, the baby may develop memory and concentration issues as they grow.

Breastfeeding mothers who also use cannabis may be exposing their baby to its potentially harmful effects. Women should avoid using cannabis while pregnant and breastfeeding.

Cannabis may affect the brain development of older children and teenagers. This can lead to memory loss, concentration issues, and impaired problem-solving skills.

Research strongly suggests that for those under 25 years of age, cannabis use can impair memory and learning ability.

Long-term effects depend on several factors, including:

  • how a person uses cannabis
  • how often they use it
  • the age of the person using it
  • how much a person uses at any given time

Some of the potential long-term effects include the following:

  • short-term memory loss
  • concentration and memory issues from exposure while in the womb
  • lung irritation
  • possibly lung cancer, although research does not fully support this
  • development of cannabinoid hyperemesis syndrome, which causes nausea and vomiting

However, it is important to note that more research is still necessary to understand the potential long-term effects of cannabis. Much of the research is retrospective and took place prior to cannabis legalization, meaning products may contain unknown chemicals.

Additionally, it is important to distinguish the potential long-term effects that occur due to smoking cannabis, and not necessarily from cannabis itself. For example, possible lung problems and complications that affect a fetus occur as a result of smoking, and not from using cannabis.

Smoking cannabis has many potential short- and long-term effects on the body. Although many proponents believe that cannabis is a modern-day cure-all, others believe that the negative effects of smoking cannabis outweigh its potential medicinal benefits.

While cannabis could have many potential benefits, smoking cannabis may result in a variety of health complications. More research is still necessary to explore the effects on the body and the most effective ways to administer cannabis.

People have used cannabis recreationally for many years. As of 2025, 40 states in the United States have some form of legal cannabis. A few states have also legalized its recreational use.

In states where recreational use is still not legal, people should consider other approaches and consult their healthcare provider about what is best for them.