Does Marijuana Help Treat Parkinson’s Disease Symptoms?

Parkinson’s disease affects almost every aspect of someone’s day-to-day life. But for many of the half a million people in the U.S. diagnosed with the condition, the available medications aren’t always enough to treat their symptoms.

So, it makes sense that people are exploring whether cannabis (also referred to as marijuana) can help treat their condition. So far, the research is mixed about the role of cannabis in Parkinson’s disease treatment.

Can cannabis help people with Parkinson’s disease?

It's not clear if cannabis can help people with Parkinson’s disease. 

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People have reported that cannabis helps reduce symptoms such as tremor, slow movement, and pain. And early research suggests that cannabis may help Parkinson’s disease. However, experts are waiting on large-scale clinical trials to better understand the potential benefit. 

Given the way cannabis works in the body, it makes sense that it has potential to help with Parkinson’s. Cannabis contains active ingredients called cannabinoids. Two of the main ones are:

• THC (tetrahydrocannabinol), which is responsible for the mind-altering and mood-enhancing effects of cannabis

• CBD (cannabidiol), which has anti-inflammatory properties that help relieve symptoms of pain and anxiety

Cannabinoids bind to receptors throughout the body, especially in the brain and nervous system. These receptors play an important role in things like mood, thinking, and movement. So it’s no surprise that people are using it for a variety of neurological disorders — from traumatic brain injury to multiple sclerosis. And it’s possible that the anti-inflammatory effect of certain cannabinoids could have a role in treating Parkinson’s disease. 

Parkinson’s is caused by the death of neurons in a specific part of the brain. This part of the brain also contains many of the receptors bound by cannabinoids. And some researchers think that cannabis’s effect on these receptors might help protect brain cells from damage. 

Some studies have found encouraging results. But the Parkinson’s Foundation doesn’t currently recommend people use cannabis to treat their symptoms or slow disease progression. Part of the reason for this recommendation is that there isn’t enough research to draw any firm conclusions yet.

EXPERT PICKS: WHAT TO READ NEXT

• The pros and cons of cannabis: Learn about the potential health benefits and safety risks of cannabis as a medical treatment.

• How does weed affect the brain? Long-term use of cannabis can have lasting effects on brain function and mood.

• Safe cannabis use: If you’re considering trying cannabis to treat a medical condition, it's important to know how to do so safely.

What research exists on the effects of cannabis for Parkinson’s?

When experts look at all the available research on the effects of cannabis on Parkinson’s disease, they all come to a similar conclusion — we need more information. Even though there are smaller studies that do report improved symptoms with cannabis use, researchers agree these studies don't meet high enough quality standards.

The main concerns with these studies are that they’re:

• Small: Only a few participants were in the study.

• Not controlled: This means there’s no comparison group that receives a placebo instead of cannabis. And cannabis isn’t compared to existing treatments for Parkinson’s.

• Open label: This means both the researchers and the participants know they’re receiving cannabis. So the results are highly prone to bias.

• Not standardized: The studies lacked any sort of standardized cannabis dosing or treatment protocol.

This doesn’t mean cannabis has no future role in Parkinson's treatment. It means researchers need to conduct more studies. 

As mentioned in the previous section, cannabis has positive effects on the brain that may impact Parkinson’s disease. And there are studies in lab and animal models that suggest cannabis may help with:

• Motor (movement) symptoms, like tremors and rigidity

• Non-motor symptoms, like mood and pain

• Movement side effects related to prescription medications that treat Parkinson’s

In small, non-controlled studies, people with Parkinson's do report improvement in their symptoms with cannabis use. These symptoms include: 

• Tremors

• Rigidity

• Slow movements

• Sleep

• Pain

A survey study found that about half of people with Parkinson's report symptom improvement with cannabis. Another survey study found that people with Parkinson's mainly used cannabis for anxiety, pain, and sleep. But about 1 in 4 users also stopped taking cannabis because their symptoms hadn’t improved.

So even the anecdotal reports are a bit mixed. But it’s likely these mixed results are also related to: 

• The variation in symptoms from person to person 

• Someone’s stage of Parkinson’s disease

• The dose, form, and frequency of cannabis use

Are there any risks with using cannabis for Parkinson’s?

Like any medication or treatment, it's important to be aware of the risks associated with cannabis use. These include: 

• Side effects

• Toxicity (possible overdose)

• Dependence (needing to continue using cannabis)

• Medication interactions

Below, we’ll go into each risk in more detail.

Side effects

Cannabis may cause unwanted side effects that include:

• Difficulty thinking 

• Short-term memory loss

• Dizziness

• Blurred vision

• Problems with balance and coordination

Long-term or frequent use of cannabis may also increase your risk of:

• Lung damage — from inhaled cannabis products —that can lead to conditions like COPD (chronic obstructive pulmonary disease)

• Heart disease and heart attacks

• Stroke 

• Cannabinoid hyperemesis syndrome, a condition that causes uncontrollable vomiting

• Anxiety and depression

Toxicity

It's possible to overdose on cannabis, although it’s not typically a life-threatening issue. An overdose is more likely with edible products. That’s because edibles’ effects can start and last in unpredictable ways. For example, it can take as long as 2 to 4 hours to notice the effects. And these effects can then last up to 6 to 8 hours. So it's easy for people to think they need a higher dose and end up taking too much. 

It's less common to overdose on cannabis when you smoke it, but it's still possible. This is especially the case with cannabis products that contain a high amount of THC compared to CBD. High doses of THC can lead to:

• Agitation, anxiety, or paranoia

• Hallucinations

• Psychosis

• Chest pain or rapid heart rate

• Nausea and vomiting

• Seizure

Dependence 

Repeated cannabis use can lead to dependence. This is when you need to continue using a substance in order to function. And sometimes, this dependence can lead to misuse. This is called cannabis use disorder. Research estimates that about a third of people who use cannabis experience dependence. 

Most (but not all) people who use cannabis heavily will experience withdrawal symptoms when they cut back. These symptoms include:

• Sleep problems or insomnia

• Loss of appetite

• Anxiety

• Strong cravings

Medication interactions

Cannabis is processed in the liver. This process uses similar enzymes that the body uses to break down other medications. This means that when cannabis and other medications are in the body at the same time, the liver may have a hard time processing them both. This can lead to:

• Increased risk of unwanted side effects from cannabis

• Toxic levels of medications 

• Decreased effectiveness of other medications

If you take any medications that interact with grapefruit, there’s a chance they may interact with cannabis too. This is why it's important to discuss cannabis use with your primary care provider. They can help you figure out if it's affecting your other medications and how to adjust your medications to make it safer for you.

What’s the best way to use cannabis for Parkinson’s?

Medical cannabis is legal in 38 states, the District of Columbia, and three U.S. territories. Of these, 17 states consider Parkinson’s disease a qualifying condition for medical cannabis use. Most states also include severe muscle spasms and chronic pain as qualifying conditions, which are often symptoms associated with Parkinson’s.

If you’re thinking about using cannabis to treat your Parkinson’s symptoms, talk to your healthcare team first. They can help you weigh the benefits and risks unique to your condition and current treatment plan. You should also only purchase cannabis products from a licensed dispensary to ensure their quality and safety is regulated. 

Since there’s no standard dose of cannabis for Parkinson’s, it’s best to err on the side of caution: 

• Begin with a low dose. If you need to, you can gradually increase it over several days or weeks. 

• Avoid cannabis products with high doses of THC. Since THC specifically can lead to issues with thinking and balance, high doses could potentially worsen symptoms of PD.

• For edibles, beverages, and tinctures, start with 1 mg to 2.5 mg of THC. 

• For smoked or vaporized cannabis, start with one puff, and wait 15 minutes before taking another one. Look for inhalable products with a few milligrams of THC or a low percentage of THC. 

It’s also helpful to look for high-CBD cannabis or products with a balanced ratio of CBD to THC. CBD can help reduce some of the unwanted side effects of THC and have benefits of its own.

Why trust our experts?

Written by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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