Cannabis and Blood Pressure: What the Research Says

Cannabis is becoming more mainstream, from medical use to casual relaxation. But if you have high blood pressure, it’s not as simple as lighting up or sipping an infused tea. Cannabis can have real, measurable effects on your cardiovascular system - some beneficial, others potentially risky.

In this article, we’ll look at the latest research on cannabis and blood pressure, what it means for people with hypertension, and how to approach cannabis use with safety in mind.

How Cannabis Affects Blood Pressure

Cannabis can have complex effects on your cardiovascular system, and the impact depends on many factors, including the dose, the type of cannabinoid, and your body’s own sensitivity.

THC (tetrahydrocannabinol), the main psychoactive compound in cannabis, typically causes a temporary increase in heart rate and blood pressure right after use. This can be followed by a drop in blood pressure - sometimes called postural hypotension - which is why some people feel dizzy or lightheaded after consuming cannabis.

CBD (cannabidiol), on the other hand, has a different profile. Early studies suggest it may help lower blood pressure in certain settings, possibly due to its relaxing effects on blood vessels and the nervous system.

Researchers believe that THC’s increase in blood pressure and heart rate is due to its stimulation of the sympathetic nervous system - the part of your body responsible for “fight or flight” responses. This stimulation leads to a temporary narrowing of blood vessels and faster heartbeats.
Later, THC can cause a sudden drop in blood pressure (postural hypotension) likely due to vasodilation in certain blood vessels or direct effects on the vascular system.

CBD, in contrast, may support blood vessel relaxation by interacting with the endocannabinoid system and possibly with serotonin receptors. CBD’s mild anti-inflammatory effects could also contribute to slightly lower blood pressure in some settings.

Key Points:

• THC → brief increase in blood pressure and heart rate
• THC → may cause a sudden drop in blood pressure when standing up
• CBD → may lower blood pressure slightly in some cases

But these effects aren’t always predictable. That’s why understanding the research is essential - especially for those already managing high blood pressure.

The Latest Research: What Do Studies Say?

While cannabis and cannabinoids have been studied for decades, their effects on blood pressure are still being clarified by modern research.

A 2017 study published in the Journal of Clinical Investigation found that a single dose of CBD (600 mg) led to a reduction in resting blood pressure in healthy volunteers. 

Researchers suggested that CBD’s effects on the nervous system might help relax blood vessels.

However, THC shows different patterns. A 2021 review in the American Journal of Medicine highlighted that THC can cause transient increases in blood pressure and heart rate, especially in occasional users. This effect may be more pronounced in people with existing hypertension.

Other small studies suggest that cannabis may also contribute to postural hypotension - a sudden drop in blood pressure when standing up, which can lead to dizziness or even fainting.

Despite these findings, researchers caution that the long-term effects of cannabis use on blood pressure remain unclear. Current studies are often limited by small sample sizes and differences in cannabis products and dosing.

Summary:

• CBD: may reduce blood pressure slightly in healthy people
• THC: can cause brief increases in blood pressure, followed by possible drops
• More research is needed to confirm these effects in people with hypertension

Risks for People with Hypertension

For people with high blood pressure, cannabis use isn’t without its risks. Here’s what the research says - and why caution matters.

1. Sudden Increases in Blood Pressure

THC can cause a temporary increase in blood pressure and heart rate shortly after use. While this spike usually doesn’t last long, it can be risky for those with poorly controlled hypertension or a history of cardiovascular problems.

Even a brief increase can strain the heart and blood vessels, raising the chance of chest pain, heart attack, or stroke, especially in older adults or those with underlying heart disease.

2. Postural Hypotension

Cannabis, particularly THC, can also trigger postural (orthostatic) hypotension - a rapid drop in blood pressure when standing up. This can cause:

• Dizziness
• Lightheadedness
• Fainting
  These sudden drops in blood pressure can increase the risk of falls, which is particularly dangerous for seniors and people with balance issues.

3. Interactions with Blood Pressure Medications

Cannabis can interact with many antihypertensive drugs, including:

• Beta blockers (like metoprolol, propranolol)
• Calcium channel blockers (like amlodipine, verapamil)
• Diuretics (like hydrochlorothiazide)
• ACE inhibitors and ARBs (like lisinopril, losartan)

These interactions may:

• Change how the medications are broken down in the liver (via CYP450 enzymes)
• Reduce the effectiveness of blood pressure control
• Increase side effects like dizziness, fatigue, or abnormal heart rhythms

4. Long-Term Risks Still Unknown

Long-term studies on cannabis use and blood pressure are limited. We don’t fully understand how regular cannabis use over years might affect blood pressure stability or contribute to cardiovascular risks.

Why This Matters

For anyone with hypertension - or anyone taking medications for it - cannabis use needs to be approached with caution. It’s not about fear or prohibition; it’s about recognizing that cannabis, like any active substance, can have real impacts on heart health.

Talk to your doctor before trying cannabis if you have high blood pressure. They can help you weigh the potential benefits and risks, and figure out if cannabis is safe for you.

It’s important to note that medical cannabis use - often under a doctor’s supervision with controlled dosing - can be very different from recreational use, which may involve higher doses and less reliable sources. For people with high blood pressure, this difference matters.

Method of Consumption Matters

The way you use cannabis can have a big impact on how it affects your blood pressure.

• Smoking or Vaping: Rapid absorption of THC, leading to quick peaks in blood pressure and heart rate. This can make sudden dizziness or a racing heart more likely.
• Edibles or Drinks: Slower absorption through the digestive system, but the effects last longer. Edibles convert THC to 11-hydroxy-THC, which is stronger and may be more unpredictable. This can be riskier for people with hypertension.
• Topical Products: Typically do not enter the bloodstream in significant amounts and are unlikely to affect blood pressure.

Being aware of how you consume cannabis is just as important as how much you use - especially if you have high blood pressure.

Tips for Safer Use (If You Choose to Use Cannabis)

If you have high blood pressure and are considering using cannabis, taking a few careful steps can make a big difference in safety.

1. Start Low and Go Slow

The effects of cannabis - especially THC - can be unpredictable. Start with low doses and wait to see how your body reacts before using more.

2. Monitor Your Blood Pressure

Keep track of your blood pressure at home, especially in the hours after using cannabis. If you notice any concerning changes - like sudden spikes or dizziness - it’s a sign to stop and talk to your doctor.

3. Choose CBD-Rich Products if Possible

Early research suggests that CBD may help relax blood vessels and lower blood pressure slightly, without the temporary spikes that THC can cause. If you’re using cannabis for relaxation, consider CBD-dominant options.

4. Avoid Mixing with Alcohol or Other Substances

Combining cannabis with alcohol or certain prescription drugs can further destabilize blood pressure and increase the risk of dizziness or falls.

5. Always Consult Your Doctor

This isn’t just a precaution - it’s an essential part of using cannabis safely. Your doctor can help you understand the potential risks, check for drug interactions, and advise on whether cannabis is appropriate for your health situation.

What’s Next? The Need for More Research

While the studies we have so far offer important insights, there’s still a lot we don’t know about how cannabis affects blood pressure, especially in people with hypertension.

Why More Research Matters

• Many existing studies are small or based on short-term use.
• We need larger, longer studies to understand the long-term impact of regular cannabis use on blood pressure control and cardiovascular health.
• It’s also unclear how different doses and cannabis products (edibles, tinctures, vapes) might affect people differently.

Researchers are calling for:

• More clinical trials focused on patients with hypertension
• Deeper looks at how CBD vs. THC might play different roles
• Studies that include older adults and those with other health conditions

For now, caution is the best approach. Until we have clearer answers, people with high blood pressure should treat cannabis as a substance that can influence cardiovascular health - and not assume it’s harmless or “neutral.”

Chronic vs. Acute Use: What We Know

Most studies so far look at short-term (acute) effects of cannabis on blood pressure. But what about people who use it daily?

Long-term use of cannabis has shown mixed results in research:

• Some studies suggest it could increase the risk of hypertension and cardiovascular problems.
• Others have not found a clear link.

This area is still being investigated, and for people who use cannabis regularly, especially in large amounts, caution and regular monitoring of blood pressure are essential.

What to Do if You Feel Side Effects

If you experience dizziness, lightheadedness, or a racing heart after using cannabis:

• Sit or lie down immediately to reduce the risk of falling.
• Raise your legs if you feel faint - this helps blood flow back to your brain.
• Stay calm - anxiety can make symptoms feel worse.
• If symptoms persist or worsen, seek medical help right away.

Cannabis use is becoming more common, but for people with high blood pressure, it’s important to remember that cannabis isn’t risk-free. THC can cause temporary spikes in blood pressure and heart rate, while CBD might have a more calming effect - but research is still ongoing.

For people with hypertension, these effects matter. The potential for interactions with blood pressure medications, along with the chance of dizziness or sudden drops in blood pressure, means cannabis should be used cautiously.

Above all, remember: cannabis is not a treatment for high blood pressure. Before using it, especially if you have cardiovascular concerns, always talk to your doctor and make sure you’re making choices that support your overall health.