There is little official guidance on using cannabis after surgery. Research on the effects of cannabis on surgery, anesthesia, and surgical recovery lags behind its use. For this reason, most surgeons recommend avoiding it before surgery and sometimes after.

After surgery, the risks of cannabis are unclear, but it may increase the risk of vomiting or nausea or require more medication for someone to manage their pain.

People who use cannabis may be reluctant to tell their healthcare professional about their use, particularly if the drug is illegal in their region. However, doctors are not police officers and can offer specific, personalized advice on the risks of cannabis when recovering from surgery.

If a person feels they cannot stop using cannabis, their qualified healthcare professional may offer additional medications or treatments to ease withdrawal and addiction.

This article examines what happens to the body if someone smokes after surgery and whether it is safe to do so.

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In almost all cases, a person has the right to make their own medical decisions. So, an individual who has had surgery can smoke weed as long as they are not staying in a hospital where safety rules prevent it.

However, little research has investigated the safety of smoking cannabis after surgery. As a result, a healthcare professional knows that it carries some risks, such as more pain and nausea. However, they do not know if there is a safe level or if these factors change for people with addictions or users of medical cannabis.

Moreover, most studies of cannabis use in people undergoing surgery have focused on using cannabis before surgery, not after. It is likely, though not certain, that the effects are similar. Without further research, it is not possible to make evidence-based recommendations.

For this reason, most qualified healthcare professionals recommend avoiding cannabis in the days surrounding surgery.

Learn more about cannabis.

The risks of smoking cannabis after surgery are not fully certain, given that very little research has investigated the subject.

A 2018 study found that the effects of cannabis peaked 1 hour after smoking and that in the time following smoking, it had links to a heightened risk of:

Before surgery, cannabis can increase airway difficulty and require anesthesiologists to use more anesthesia.

The study found contradictory results regarding its effect on blood clotting, with data suggesting that it could increase blood clots and decrease them. Both could be potentially dangerous, with the former increasing the risk of embolism and the latter increasing the risk of bleeding.

According to the American College of Surgeons, cannabis use has links with a greater need for pain medication and anti-nausea medication following surgery.

Research has not pointed to any specific benefits of smoking cannabis after surgery, but the potential medical benefits of cannabis may extend to post-surgical recovery. Cannabis could, for example:

  • improve sleep
  • reduce pain or anxiety
  • reduce complications of other medical conditions, such as cancer-related nausea

However, this is speculative, since recent research has not assessed the potential benefits.

For habitual users, using cannabis after surgery may reduce the risks of unpleasant withdrawal.

Learn more about the benefits of cannabis.

Some of the risks of smoking weed before surgery may be long term. Research, for example, shows that in surgery, the lung risks of smoking weed are similar to those of tobacco. Other risks may be lower shortly after abstaining from weed.

Drawing on data from a 2018 study, the American College of Surgeons recommends quitting weed at least 72 hours before surgery. People with a history of addiction or at a high risk of withdrawal may benefit from abstaining earlier so that they do not experience withdrawal while recovering from surgery.

According to a 2023 review, using cannabis correlates with a greater need for pain control after surgery. Other data supports this finding. The American Society of Anesthesiologists advises that using cannabis may increase pain and can make managing it more complicated. This is because qualified healthcare professionals may have to adjust pain medication dosage.

However, this association is complicated. Some healthcare professionals prescribe cannabis for pain, and some people use cannabis to self-medicate their pain. So, those who use cannabis may have higher pain to begin with or a higher risk of pain for reasons unrelated to cannabis.

Cannabis could also alter the body’s pain perception in other ways, increasing post-operative pain. In people with addictions, withdrawal could intensify pain perception.

Many different explanations exist, and each of these explanations may play a role. Because healthcare professionals do not yet know why there is an association between cannabis and pain, they usually advise avoiding the drug.

People experiencing pain need to tell their healthcare professionals who can help them find the right pain relief.

Learn more about pain and cannabis.

There is a lack of research on cannabis use and safety after surgery, particularly in people with addictions and those who use cannabis for medical reasons. This means a qualified healthcare professional cannot confidently advise on what level of cannabis is safe or when people can use it again.

Still, it can be difficult to quit using cannabis, especially if a person uses it to control anxiety or other medical symptoms. Withdrawal symptoms can also make surgical recovery more difficult. So, it is important to discuss the risks and benefits with a qualified healthcare professional and any harm mitigation strategies.

If a qualified healthcare professional cannot provide guidance, a person needs to consider getting a second opinion from another healthcare professional who is knowledgeable about cannabis. People with a medical cannabis prescription need to consult the qualified healthcare professional who authorized the recommendation.