Why Does Marijuana Make Your Heart Race? [The Science Behind]

Humans have used cannabis as a medicine for thousands of years. However, it has only recently returned to popularity after being illegal for most of the last century. Now, the majority of states have medical marijuana programs in place, and people are using weed to treat a wide range of conditions. A number of states also have recreational laws in place.

One of the major advantages of cannabis as a medicine is its relative lack of side effects. Many patients find it easier to tolerate than conventional treatments, which often have long lists of possible reactions.

However, marijuana is not completely free of adverse effects. It can cause dry mouth and eyes, drowsiness, dizziness, and increased anxiety and paranoia in susceptible people. Cannabis can also cause your heart to race, a distressing side effect if it catches you by surprise. Furthermore, some people even claim that weed can increase your risk of heart attacks.

In this article, we explore whether there is any truth behind these claims and why marijuana makes your heart race.

How Marijuana Affects Your Heart

Cannabis exerts most of its effects on the body by interacting with the endocannabinoid system (ECS). This system is a series of cell receptors known as cannabinoid receptors and chemicals called endocannabinoids.

The cannabinoid receptors that we know the most about are called the CB1 and CB2 receptors. They are located throughout the body and play a role in many of our physiological functions. When cannabinoid receptors and endocannabinoids come into contact with one another, they trigger a series of different reactions.

The ECS is involved in mood, movement, and appetite, among other things. However, one of its most crucial roles is maintaining homeostasis. This is a state of constant internal balance in an ever-changing external environment.

Maintaining homeostasis requires continual monitoring and adjustment of factors like body temperature and blood pressure. Therefore, it is no surprise that scientists have discovered endocannabinoids in the tissues of the heart.

The ECS appears to play a vital role in controlling blood pressure, causing blood vessels to relax and widen (vasodilation). It also influences heart rate, and this is where cannabis comes into the picture.

The cannabis plant produces hundreds of different chemicals that impact your body in different ways. One of the most prominent is THC, the compound that gives marijuana its intoxicating effects. THC affects your body so dramatically because it has a similar chemical structure to your natural endocannabinoids.

Therefore, it can bind with cannabinoid receptors and trigger many of the same reactions. As well as the typical marijuana ‘high,’ THC is responsible for many of weed’s medical benefits. However, when you take it in excessive doses, it can also have some negative side effects.

Why Does Cannabis Make Your Heart Race?

When THC from cannabis binds with your cannabinoid receptors, it affects many of your biological systems, including your heart. It causes your heart to pump harder and faster, as well as making the blood vessels dilate. THC also acts independently of the ECS and affects a system called the transient receptor ankyrin type-1 (TRPA-1) channel. This causes further vasodilatory effects.


Under normal circumstances, a healthy person should have a resting heart rate of 60–100 beats per minute. However, after smoking weed, this can increase by 20–100%. Furthermore, these effects may last for as long as 2–3 hours.

It is unclear exactly why marijuana makes your heart race in this way. However, scientists believe that it could be a result of excessive vasodilation. During vasodilation, the blood vessels become wider and, therefore, blood pressure decreases. In response, the heart beats faster to compensate. This phenomenon is known as reflex tachycardia.

The fact that cannabis dilates blood vessels and reduces blood pressure also causes some people to feel dizzy or faint after smoking weed.

The good news for cannabis users is that these effects quickly wear off once you build up a tolerance. Research shows that people who smoke weed regularly (six or more times weekly) are less likely to experience these effects.

In fact, frequent users may have lower than average heart rates and increased blood volume. Also, their circulatory systems may be affected less by physical exercise. This is likely due to increased activity in the parasympathetic nervous system, which we associate with rest and relaxation.

Does Marijuana Increase Heart Attack Risk?

Some studies have suggested that marijuana could increase your risk of cardiovascular problems, including heart attacks. Data collected by the French Addictovigilance Network between 2006 and 2010 indicate that 1.8% of cannabis-related adverse effects involve the cardiovascular system. The issues mainly affected men (85.7%) with an average age of 34.3 years.

These events included 22 cardiac, 10 peripheral vascular, and 3 cerebrovascular complications. In 9 cases (25.6%), these complications were fatal.

There have been several other reports of heart attacks in otherwise healthy people after smoking cannabis. Some figures estimate that the risk of heart attack is increased 4.8 times within the first hour after smoking weed. The risk is higher with strenuous physical activity or the use of other substances such as ecstasy/MDMA.

Although the risk is still relatively low for people without pre-existing heart problems, it could be significant for those with cardiovascular disease. Therefore, if you have heart disease or other risk factors for heart attacks, you may be better off avoiding cannabis. Talk to your healthcare provider about what alternatives are available to you.

In addition to increasing the risk of heart attacks, marijuana may contribute to conditions like angina, strokes, and atrial fibrillation. People who suffer from cardiovascular diseases are more likely to experience chest pain after using cannabis and should exercise caution.

If you have smoked cannabis and suffer from severe chest pain, seek medical attention immediately. This is especially important if you also experience breathing difficulties, weakness, or pain in the jaw, shoulder, back, or arms.

Benefits of Cannabis for Heart Health

While marijuana has the potential to impact your cardiovascular system negatively, it could have some potential benefits, too. For example, CBD, another chemical in cannabis, has powerful anti-inflammatory properties. It interacts with CB2 receptors in the ECS to dampen the inflammatory response. Inflammation is often a contributing factor in heart disease and, therefore, reducing it could offer some protection.

Research has also shown that CBD might help with addictive behavior, including tobacco smoking. Since smoking cigarettes is one of the biggest risk factors for heart disease, stopping could have obvious benefits.

Finally, there is some evidence that regular cannabis users have lower rates of obesity and diabetes. These are two conditions that experts frequently link with chronic inflammation and heart disease.

So, it’s not all doom and gloom when it comes to cannabis and your heart. However, if you have a heart condition or other risk factors, it is advisable to exercise caution.

Why Does Marijuana Make Your Heart Race? Final Thoughts

Marijuana can influence many of your body’s systems through its interaction with the endocannabinoid system. This includes increasing heart rate and reducing blood pressure. However, these effects become less significant as you build a tolerance to THC.

There is no doubt that having a racing heart can be scary when you’re high. This is especially true when you are not expecting it and it hits you out of the blue. One thing to remember is that marijuana can also make you anxious if you take a high dose. Anxiety can contribute to symptoms such as a racing or pounding heart, and palpitations.

Therefore, you can reduce the likelihood of these side effects occurring by starting low and slow.  You can then increase your dose slowly over time until you find a level that suits you. It is also advisable to only use cannabis in a safe and familiar environment with people you trust. This will reduce the chance of anxiety attacks and their accompanying symptoms.

If you do experience a racing heart after smoking weed, try to stay calm. Sit down in a quiet place, take slow and steady breaths, and stay hydrated by sipping water. After a short time, these side effects should subside, allowing you to relax and enjoy your high.

However, if they do persist or if you experience chest pain alongside other symptoms, see a physician immediately. This will allow you to rule out more serious complications and should help to put your mind at ease.

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