With the exception of dry mouths and red eyes, most people with a medical marijuana card can use cannabis without any problems. However, “vasovagal syncope,” or fainting, is a rare and unpleasant side effect that only a small percentage of people will encounter.
Some researchers claim that THC causes the body’s blood pressure to drop, which is why these blackout periods happen. The body is unprepared for the abrupt drop in pressure, and in extremely rare instances, a person passes out.
Despite the rarity of the experience, it’s helpful to understand why people pass out from marijuana use and how to lessen or stop the incident before it happens. What the science says is as follows:
The Link Between Marijuana Use and Fainting
Some cannabis users experience fainting spells as a result of vasovagal syncope, a type of fainting. Other forms include situational syncope, which is brought on by coughing and urinating, and carotid syncope, which happens when your carotid artery is constricted.
There are several explanations for why marijuana use can result in vasovagal syncope. The reduction in blood pressure brought on by cannabis use is one such feature.
Among the primary cannabinoids in medical marijuana is THC, which dilates blood vessels and is therefore a vasodilator. This effect is one of the reasons people with hypertension, or high blood pressure, use medical marijuana; however, the drop in blood pressure can be fatal for people who already have low blood pressure. THC also generally elevates the heart rate, which lowers blood pressure and heightens the chance of fainting.
Understanding How Vasovagal Syncope Occurs
When the parts of the nervous system that control blood pressure and heart rate react to a trigger stimulus—such as seeing blood or experiencing another emotionally upsetting event—vasovagal syncope happens.
Abruptly, the heart rate drops, and the leg blood vessels widen. Blood leaves the brain and momentarily renders you unconscious as it travels directly down to your legs.
Above all, vasovagal syncope is a benign condition that doesn’t need to be treated. People can hurt themselves when they faint, for example, by falling and hitting their heads on a table (which is definitely not a good idea). Tests to rule out more serious causes of fainting, like heart disease or another underlying medical condition, may be advised by a doctor.
Factors That Can Increase the Risk of Fainting
Few studies have looked into the relationship between marijuana use and lightheadedness or fainting. It appears that the primary conclusions are that the individual and their surroundings play a major role in marijuana-related fainting.
For instance, six out of ten participants in a Duke University study reported feeling “moderate” to “severe” dizziness after smoking a joint. But their experience appeared to be influenced by factors related to their blood pressure and heart health. This suggests that people who smoke cannabis and already have low blood pressure may be more prone to dizziness.
Similar findings were observed in another study, where participants who reported feeling lightheaded after standing up displayed lower blood pressure and pulse rates than those who reported fewer symptoms.
The fact that cannabis can dramatically lower blood pressure, which can result in a lack of blood supply to the brain and cause users to pass out, makes these results not shocking. However, there are a number of additional biological mechanisms that may be involved in the fainting experience that cannabis may interact with, but we haven’t fully understood them without more research.
Lastly, how cannabis is smoked may also have an effect on a person’s risk of fainting. The rapid entry of cannabinoids into the body caused by smoking or vaporizing cannabis can also cause a shock to the system when someone consumes THC quickly. Edibles and oils are among the other consumption methods that may reduce the chance of fainting because they take longer to start working.
Warning Signs
Vasovagal syncope can cause any of the following warning symptoms, which a person may encounter prior to fainting:
- Paleness
- Tunnel or blurred vision
- Nausea
- Lightheadedness
- Warmth
- A cold sweat
The following are possible observations made by onlookers during a vasovagal syncope episode:
- Dilated pupils
- Jerky movements
- A slow or weak pulse
Within less than a minute following an episode of vasovagal syncope, people recover. But for the next 15 to 30 minutes, it’s best to remain seated, as getting up too soon after fainting can make it more likely that you will faint again.
How to Avoid Fainting When Using Cannabis
People who use cannabis occasionally, but not always, can prevent a vasovagal syncope episode if they sense symptoms approaching. If you think you might pass out, lie down and raise your legs so gravity can continue to pump blood to your brain. If it is not possible for you to lie down, sit with your head between your knees until the symptoms go away.
There are a few things you can try before using cannabis to prevent passing out:
- Try a new strain: One way to counteract the strain’s tendency to dilate blood vessels and cause hypotension is to switch to one with less THC. This way, the effects of the THC will be lessened, and your blood pressure won’t plummet too much.
- Sit or lie down: By lowering the distance your blood must travel compared to when you’re standing, using medical marijuana while sitting or lying down also lowers your chance of fainting.
- Open a window: If you feel dizzy, the fresh air or a breeze can also help you relax.
- Switch to edibles or oils: These methods allow your body to adjust to THC levels more gradually and with less effect.
For advice on how to modify your treatment plan, speak with your medical marijuana doctor if you frequently experience fainting episodes while using cannabis.
The Conclusion
While many patients find medical marijuana beneficial, most people won’t put up with fainting as a side effect. Fortunately, there are proactive and reactive methods one can take to avoid fainting spells when using cannabis, so one can continue to reap the health benefits of the plant without having to worry about experiencing a fainting episode.
In your home state, apply for a medical marijuana card. There are several online clinics now open and available to provide you with helpful advice while you proceed with the application process.
