Before using CBD to reduce anxiety or to lower blood pressure, speak with your doctor about possible CBD and drug interactions.

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CBD, or cannabidiol, is an active ingredient of marijuana, but it is not the same as THC. THC causes the marijuana “high,” which CBD does not do. You may find CBD advertised as a treatment for anxiety, insomnia, or as a pain reliever. According to the Natural Medicines Comprehensive Database, CBD is likely to be effective for certain types of epilepsy, but there is not enough evidence from human studies to know if CBD is effective for anything else. Some early research shows possible benefits for reducing anxiety and pain.

What Are the CBD Effects on Blood Pressure?

As far as blood pressure, “animal studies suggest CBD has anti-hypertensive effects.  However, human data is incredibly limited to a few studies, which show one-time administration of CBD was able to lower blood pressure temporarily in healthy individuals,” says Jeff Chen, MD, CEO and Cofounder of Radicle Science. These two studies have been done with CBD for lowering blood pressure:

• A small study in 2017 found that one dose of CBD given to healthy volunteers could lower blood pressure at rest and during stress, better than a placebo. Previous studies in animals suggest that CBD could reduce blood pressure. In this study, nine healthy men were given a placebo or CBD. The researchers concluded that the role of CBD in blood pressure needs more study to see if it has a role in lowering high blood pressure.
• A 2020 study done on human lung tissue (after lungs had been removed due to lung cancer) found that treating the lung arteries with CBT could cause the arteries to open (called dilation). The researchers conclude that this could be a way to treat high blood pressure, since dilated arteries lower blood pressure. More studies would need to be done in live humans with high blood pressure.

“The one study that did find CBD to be effective in lowering blood pressure used an oral form of purified CBD and a dose of 600mg. 600mg is more than 10-times higher than the average dose of a commercially sold, over-the-counter CBD product,” says Winston Peki, owner and editor of Herbonaut. Over-the-counter CBD products are typically no higher than 50mg, so the effective amount of CBD to lower blood pressure is quite high.

What About Safety and CBD Drug Interactions?

According to the Natural Medicines Comprehensive Database, CBD is possibly safe when taken as directed by mouth or sprayed under the tongue up to a dose of 300 milligrams per day over 6 months. Higher doses, up to 1500 mg per day have been taken safely for up to four weeks.

The most common side effects of CBD are drowsiness, dry mouth, dizziness, irritability, agitation, diarrhea, and loss of appetite. In rare cases, CBD may cause liver damage. CBD is not considered safe during pregnancy or breast feeding. If you have liver disease, ask your doctor if CBD is safe. Same thing if you have Parkinson’s disease, CBD may increase PD tremors.

Medications that are broken down (metabolized) in the liver may be affected by CBD. The enzyme in the liver that breaks down medications is called Cytochrome P450 (CYP450), and CBD may slow down the process.

“CBD is a known inhibitor of CYP450 enzymes. Researchers estimated that approximately 60 percent of clinically prescribed drugs are metabolized by CYP450 enzymes. This means that CBD can block or delay the metabolization of many prescription drugs,” says Peki.

Another common inhibitor of CYP450 is grapefruit juice. It can have the same effects as CBD, that’s why you get a grapefruit juice warning on many drugs. Here is a partial list of drugs that are broken down in the liver by CYP450. Any of these drugs could have stronger or longer effects and more side effects if taken along with CBD:

• Mental health drugs, including Elavil, Haldol, Seconal, Tofranil, Valium, and Xanax
• The antinausea drug Zofran
• Heart and blood pressure medications including Inderal, Calan, Cordarone, Losartan, Lopressor, and Procardia
• Antacid medications called proton pump inhibitors such as Prevacid, Prilosec, and Protonix
• The lung medication theophylline (Theo-Dur)
• Antiseizure medications, including Tegretol and Dilantin
• Nonsteroidal anti-inflammatory drugs like Motrin and Voltaren
• The muscle relaxer Soma
• The antibiotics erythromycin and Biaxin

“A good rule of thumb is any medication that has a grapefruit warning may also interact with CBD.” says Chen. “That’s because CBD and grapefruit exert similar effects on liver enzymes involved in drug metabolism.”

Statin Drugs and CBD

Many people take a statin drug to lower their cholesterol and their risk for heart attack or stroke. These drugs are also metabolized in the liver by CYP450 and they have the grapefruit warning. Ask your doctor about CBD if you are taking one of these statin drugs. Common brand names include Lipitor, Pravachol, Crestor, and Zocor.

Bottom Line on CBD and Blood Pressure

Although there are a few studies that suggest CBD can lower your blood pressure, the studies are small and preliminary. There would need to be larger studies in people diagnosed with high blood pressure before we can say that CBD lowers high blood pressure. If you want to use CBD for any reason, remember that it can interfere with many common medications, so talk to your doctor first.