Ask an MD: I Smoked Weed and My Heart is Pounding

"I smoked weed and my heart is pounding." It's a surprisingly common - albeit unexpected - occurrence. Cannabis provides a range of experiences. Some we love, like relief and relaxation, but other effects may not be so pleasant. 

After consuming cannabis, some people experience a racing heart, which can be troubling. We turned to Dr. Brian Kessler, NuggMD’s medical director, for answers. So why does smoking weed make your heart race? 

Why does smoking weed make my heart pound?

Researchers are still discovering new cannabinoids, which are the chemical substances in cannabis that bond with the cannabinoid receptors in the body and brain. THC (tetrahydrocannabinol) and CBD (cannabidiol) are only two of the over 100 available cannabinoids in the plant. 

When you smoke weed, and your heart is pounding, it’s normal that some individuals may become a bit paranoid and think that it may be related to heart disease. If you have existing heart issues, it is worth investigating. However, the next time your heart is racing after smoking weed, the cause may be right in your joint or bowl. 

Dr. Kessler said, “THC increases heart rate through interaction with the parasympathetic and sympathetic nervous systems.” These systems regulate two elementary body reactions. The parasympathetic nervous system controls the “rest and digest” functions. The sympathetic nervous system is responsible for the “fight or flight” reactions, which prepare the body for strenuous activities.

This sympathetic system stimulation can create a chain of events, including increased heart rate or changes in blood pressure or oxygenation.¹

Does weed increase heart rate? Why does weed make my heart race?

To determine if your heart rate increases with cannabis, you first need to know your average resting heart rate. Heart rate is measured in beats per minute (BPM). For most people, the average is between 60 and 100 BPM. 

The main reason why smoking weed can make your heart rate increase is that THC activation of the CB1 receptor leads to stimulation of the sympathetic nervous system while simultaneously inhibiting the parasympathetic nervous system.

Within minutes of using cannabis, the heart rate can become elevated, especially with concurrent use of other drugs or if you have any underlying conditions affecting the heart.

What is the average heart rate on THC? What does it mean if my BPM is higher or lower than the average?

Within minutes after using cannabis, your heart rate changes. “We know that cannabis use, particularly with high THC products, can increase the heartbeat from anywhere between 20 BPM and 50 BPM,” said Dr. Kessler. Shortly after using cannabis, your resting heart rate may rise to 120 BPM or more. 

Changes in the rate of heartbeats are normal. Our heart beats faster when we’re exercising or excited and slower when relaxed or sleeping. 

When your heart beats irregularly, it’s called a heart arrhythmia. The electrical signals that tell the heart when and how fast to beat don’t work properly.

If the heart beats abnormally fast, this is called tachycardia, which occurs when the heart beats over 100 times per minute. A slow heart rate, bradycardia, occurs when the beats per minute fall below 60. The most prevalent risk factor for bradycardia is aging; a slower heartbeat is common for those over 65. Any changes in heart rate accompanied by chest pain, shortness of breath, or fainting should be treated as a medical emergency. 

In general, using cannabis with THC will raise your heart rate. Using other drugs, in addition to cannabis, may intensify this effect. With continued use and tolerance, many people will experience this less frequently. Cannabis-induced tachycardia usually resolves itself in 5-10 minutes. 

What type of people or conditions are more susceptible to heart problems when using weed?

When screening a patient for safe cannabis use, doctors take into consideration age, overall health, and lifestyle factors. Older adults with pre-existing heart conditions, lung function impairment, or liver or kidney issues should be cautious in their approach to cannabis. Lifestyle factors, such as prescribed and over-the-counter medications, smoking, or sedentary activity levels, should be considered before using cannabis.² 

Other non-cannabis conditions can cause a racing heart, such as diabetes, thyroid function issues, too much caffeine or other stimulants, and even personal genetics.

Dr. Kessler recommends, “Older individuals and those with pre-existing heart conditions, obesity or high cholesterol should take additional precautions if choosing to use high THC cannabis products.”

What other factors can affect the heart rate when using weed?

The selection of cannabis strains and terpenes can alter the heart rate. The influence of THC on the body can increase the chances of a rapid heartbeat. Cultivars high in THC, like Godfather OG or Super Silver Haze, both typically containing more than 20% THC, may be challenging for those sensitive to increases in heart rate. Choosing a lower THC amount or a more balanced blend of THC and CBD may help.

Given its reputation for sleepiness, does indica make your heart beat fast?

THC appears to be responsible for most concerns about rapid heartbeat when using cannabis. How THC is consumed may change the onset of this condition. Topical cannabinoid creams, even those with THC, will not affect heart rate unless made with a skin-penetrating enhancer. However, the addition of lidocaine, a topical pain reliever, should be avoided in patients with heart problems.

THC in any form of edible or inhalable cannabis has the potential to cause an elevated heart rate, including tinctures and gummies. Nevertheless, physicians generally prefer these methods of consumption. Although these products often contain THC, the controlled dosing may lessen or delay the onset of a pounding heartbeat. 

If you are using any homegrown cannabis or homemade products, accurate THC level testing is likely not available. Use caution when dosing homemade edibles. Products purchased at a reputable dispensary will be labeled.    

Smoking, dabbing, or vaping cannabis, with its rapid onset and often higher THC levels, may contribute to heart palpitations. Dr. Kessler notes, “Smoking may lead to a higher resting heart rate than other consumption methods. If you have concerns or pre-existing heart conditions, it may be best to explore other methods.”³

Combining cannabis with other medications or supplements can also aggravate a rapid heart rate. Some prescriptions, such as medications for the heart, blood pressure, depression, anxiety, and thyroid, raise the resting heart rate. 

Other medications, like sildenafil (Viagra) for erectile dysfunction, relaxes blood vessels and improves blood flow. Cannabis inhibits the breakdown of Viagra, potentially increasing the amount of this medicine in the body, making it last longer and amplifying its effects.

Even supplements such as vitamin D and ginseng, especially at higher doses, can trigger a faster heart rate. Caffeine, the most commonly used stimulant, also raises cardiac output.

Although THC is responsible for the occurrence of heart palpitations, prescription, over-the-counter meds, supplements, and caffeinated stimulants should be consumed carefully if your heart rate is affected. 

Is sativa or indica worse for heart rate?

The labels of ‘sativa’ and ‘indica’ do not have any bearing on the potential effects cannabis may have on heart rate. Growers of many cultivars in the legal market aim for higher THC content in response to consumer demand. In general, many of the cultivars you see on shelves today have high levels of THC, with some reaching over 30%, regardless of the ‘sativa’ or ‘indica’ label.

Although THC is the lead cause of an increased heartbeat, terpenes may also play a role. Terpenes are the fragrant molecules found in many plants, including cannabis. Certain terpenes, such as linalool, pinene (dose-dependent), and limonene, show promise in reducing heart rate. Limonene proved effective in reducing arrhythmias in a study with rats.⁴ Other terpenes, such as citronellol, may increase heart rate.⁵ 

“Certain terpenes that are associated with specific strains may either increase or decrease heart rates,” said Dr. Kessler, “but the largest cause of increased heart rate seems to be high THC levels.”

More research is needed to pinpoint the exact cultivars, terpenes, and delivery systems to reduce fast heart rates after using cannabis.

What should I do if I feel my heart racing after using weed?

Once you have determined your heart is beating uncomfortably fast (either by observation or directly taking your pulse), you can take action to slow your rate.

Start with some measured breathing. Inhale four counts through your nose, then exhale six counts through your mouth. Dr. Kessler recommends, “Taking steps to reduce your heart rate can include reducing exposure to high heat, physician activity, and remaining seated or lying down.” The good news is this discomfort usually passes within a few minutes.

If these tips don’t work, try some quick tricks to lower the effects of THC. Sip on water, eat a healthy snack, and distract yourself with a funny movie or a conversation with an understanding friend. 

Continue to check your heart rate. Per Dr. Kessler, “A resting heartbeat should never be above 100 BPM; above this, it is recommended to seek medical attention.” If you have chest pain, shortness of breath, or fainting, get help immediately.

As the situation improves, you can take additional steps to prevent future incidents by clarifying your dosage, staying hydrated, and consuming in a relaxing setting. 

How can I minimize the risk of a higher BPM while using weed? Are there strains that don't make your heart race?

A racing heart is a normal reaction to using cannabis, but this feeling isn’t comfortable for many people. This experience is common with newer consumers and subsides as your tolerance grows. Ask for strains that won’t make your heart race at the dispensary, as the budtender may have some recommendations.

Mindful choices at the dispensary can guide you toward a better experience. Type I cannabis products have high levels of THC for specific potential benefits. These products are good to avoid if you are negatively affected by high THC. If this is the case for you, look to Type II cultivars, which have a more balanced ratio of THC to CBD, or high CBD cultivars, labeled as Type III products, that provide more CBD with small levels of THC.

A budtender will likely guide you toward strains with a lower THC profile and terpenes found beneficial by consumers for reducing anxiety, which may aid in preventing rapid heart rates. You may want to avoid terpinolene, frequently cited in user groups as an anxiety-increasing terpene. Soothing terpenes like linalool and myrcene are reported to create relaxing effects, which may help prevent the anxiety of a runaway heart.

When should I stop using weed or see a doctor?

Remember, it’s unlikely that the side effects of cannabis you experience will cause any harm. A human being is not physically capable of consuming enough cannabis to result in a deadly overdose. However, treat every new strain or product you purchase as a beginner would, going low and slow with your dose. Choose products with lower THC, and be hydrated and well-rested before use. 

If your heart does begin to race while using, stop consuming cannabis. Give your body time to adjust. The thumping heart feeling will likely subside within a few minutes. 

When you are feeling better, make a note of the cultivar you were using, along with details about the cannabinoid and terpene levels and your overall health at the time. You may want to keep a consumption journal to track what gives you the most effective relief.

Most cannabis side effects are manageable, like dry eyes, dizziness, and feeling hungry or sleepy. Some, like fainting or cyclical vomiting, may be signs you should consult your physician. 

If your heart rate remains high or you are experiencing chest pains or shortness of breath, seek medical help immediately. 

References

1. Page RL, Allen LA, Kloner RA, et al. Medical Marijuana, Recreational Cannabis, and Cardiovascular Health: A Scientific Statement From the American Heart Association. Circulation. 2020;142(10). doi:https://doi.org/10.1161/cir.0000000000000883 ↩︎
2. MacCallum CA, Lo LA, Boivin M. “Is medical cannabis safe for my patients?” A practical review of cannabis safety considerations. European Journal of Internal Medicine. 2021;89:10-18. doi:https://doi.org/10.1016/j.ejim.2021.05.002 ↩︎
3. Linneberg A, Jacobsen RK, Tea Skaaby, et al. Effect of Smoking on Blood Pressure and Resting Heart Rate. Circulation Cardiovascular genetics. 2015;8(6):832-841. doi:https://doi.org/10.1161/circgenetics.115.001225 ↩︎
4. Alves QL, Silva DF. D-Limonene: A Promising Molecule with Bradycardic and Antiarrhythmic Potential. Arq Bras Cardiol. 2019;113(5):933-934. doi:10.5935/abc.20190233 ↩︎
5. Santos MRV, Moreira FV, Fraga BP, Souza DP de, Bonjardim LR, Quintans-Junior LJ. Cardiovascular effects of monoterpenes: a review. Revista Brasileira de Farmacognosia. 2011;21(4):764-771. doi:https://doi.org/10.1590/s0102-695x2011005000119 ↩︎

The information in this article and any included images or charts are for educational purposes only. This information is neither a substitute for, nor does it replace, professional legal advice or medical advice, diagnosis, or treatment. If you have any concerns or questions about laws, regulations, or your health, you should always consult with an attorney, physician or other licensed professional.