Introduction

Multiple sclerosis (MS) is an autoimmune disease, in which the immune system mistakenly attacks the body’s own tissues. In MS, a structure called myelin that functions to protect neurons (brain cells) is targeted and damaged. Myelin forms a sheath around neurons, acting as an insulating layer that helps neurons send signals to one another.

When the myelin is lost, this is known as demyelination. This causes a whole host of conditions, ranging from vision loss, fatigue, pain, muscle spasms and stiffness (spasticity), and a lack of balance and coordination (ataxia).¹ These symptoms can occur in bouts, or flare-ups, with variable amounts of time between them. For some, with each flare-up, symptoms can become worse (which is known as progressive MS).²

Around 2.9 million people are estimated to suffer from MS globally, with about 150,000 in the United Kingdom.³ A combination of genetic and environmental factors has been proposed to increase one’s risk of developing MS.

Since there is no cure for MS, treatment for this condition focuses on alleviating symptoms. For example, corticosteroids reduce inflammation, analgesics (painkillers) target pain, and muscle relaxants prevent muscle spasms. Frequently, these treatments are not effective enough and can be accompanied by unpleasant side effects and an increased risk of other health issues.

This is why, perhaps controversially, many people living with MS have opted to use cannabis-based medications to alleviate their symptoms. Since it is a Class B drug, using cannabis recreationally is illegal in the UK. However, there is evidence suggesting that certain compounds in cannabis have therapeutic effects, and some medicines for MS and epilepsy containing them have been approved by the government, as long as certain criteria are met. Somewhat contrastingly, some studies have reported no benefit from cannabinoid-containing treatments for MS symptoms.⁴

This article aims to delve into why and how cannabis is being used to alleviate symptoms of MS. 

How does cannabis work?

Cannabis sativa is a plant containing hundreds of compounds that confer special properties, the most notable of which are called cannabinoids. Specifically, the compounds tetrahydrocannabinol (THC) and cannabidiol (CBD) are the most well-known.

THC is a psychoactive compound, which means it changes the way the brain functions. This is the compound responsible for making users high. CBD, on the other hand, is not psychoactive but does have therapeutic properties, like pain-relieving and anti-inflammatory effects.⁵ Hence, medicinal cannabis tends to have a higher amount of CBD than THC to minimise its psychoactive effects.⁶ These compounds interact with the body's endocannabinoid system (ECS). The ECS comprises cannabinoids that are naturally present in the body, their receptors, and proteins involved in making and destroying them.⁷

What are the benefits of cannabis oils for MS symptoms?

CBD and THC can be extracted from the cannabis plant and to a carrier oil, such as coconut oil. CBD oil mostly contains CBD but can have a very small amount of THC. On its own, it is not an approved medicine for MS.⁸

Muscle spasms

Muscle spasticity is primarily treated with physiotherapy and antispasmodic drugs.⁹

Sativex, an oral spray containing an equal mix of THC and CBD, is approved in the UK for muscle spasticity associated with MS. Although not in everyone, Sativex can reduce muscle spasticity by up to 30%, and some users report that it can alleviate sleep issues and bladder control problems. It is only available for those with moderate to severe spasticity and when other medicines have not helped. Importantly, Sativex can worsen other MS symptoms, like fatigue.¹⁰

There is conflicting evidence suggesting that cannabinoids can alleviate muscle spasticity. For example, one study reported that MS patients taking an extract containing THC and CBD experienced almost twice as much relief from muscle stiffness as those taking a placebo.¹¹ Contrastingly, the Cannabinoids in Multiple Sclerosis (CAMS) study, which investigated whether various THC- and CBD-containing treatments could alleviate muscle spasticity, suggested that a positive effect of these substances was only seen in MS patients experiencing both spasticity and pain.

Pain relief

Around two-thirds of people living with MS experience neuropathic pain, which is a result of nerve damage, but individuals with this condition can also experience musculoskeletal pain, which is associated with the muscles, bones, and joints.

Usually, neuropathic pain is treated with various medicines, including antidepressants, anaesthetics, and antiepileptic drugs. Unfortunately, these drugs are often fairly ineffective and come with unwanted side effects, such as fatigue, nausea, and diarrhoea.¹²

THC and CBD are believed to exert their painkilling effect through interacting with specific receptors,⁴ and there have been several studies in the USA that have suggested a pain-relieving effect of cannabis in people with MS.¹³ However, generally, evidence supporting the use of cannabis for pain relief is lacking and the long-term effects of cannabis for this purpose are uncertain. This is why no cannabis-based products are approved for treatment of chronic pain in the UK.¹⁴

Improved sleep

Around half of all people living with MS experience sleep disturbances, which can be due to a variety of reasons.¹⁵ For example, pain, muscle spasms, and involuntary limb movements can make it hard to fall and stay asleep. Also, having to urinate frequently in the night and certain medications can contribute to disturbed sleep.

In terms of cannabis’ effect on sleep, this may be through ECS receptors, which have been found to be involved in sleep induction and the control of the sleep–wake cycle. However, there are very few studies looking into this.

The size of the cannabinoid dose has been reported to influence its effect on sleep. For example, low doses of THC can promote sleep, whereas large doses can have the opposite effect. Additionally, short-term THC use appears to be better than long-term use for this purpose. Withdrawal from THC has also been found to cause sleep disturbances that can start as early as 24 hours after stopping use and can last for up to 7 weeks. It is unclear what specific effect CBD has on sleep; however, it has been suggested that it counteracts the sleep-inducing effects of THC.¹⁶

Some studies, including the CAMS study, have shown that short-term medicinal cannabis use improved muscle spasticity and pain as well as sleep.^{16, 17} However, the isolated effect of cannabinoids on sleep in people with MS is unclear.¹⁸

What are the side effects and considerations of using cannabis for MS symptoms?

As mentioned previously, THC is a psychoactive compound present in cannabis that causes its associated ‘high’. For many, this is an unwanted side effect of using cannabis oil for MS symptom relief.¹¹ Fatigue is a very common symptom of MS, and the fact that cannabis oil can worsen this can be seen as a big disadvantage of its use. Also, impaired thinking and coordination can get in the way of a person living their day-to-day life. Hence, cannabis oil might not be the best option for some.

Cannabis interacting with other medications is another concern. Certain drugs could change the way that cannabis is metabolised in the body, which, in turn, could alter its effects. Also, the specific way in which different cannabis oil formulations (i.e., with different CBD/THC ratios) react with different drugs is uncertain.¹⁸

Other unwanted effects of cannabis oil include a dry mouth, headaches, and urinary tract infections. It should be noted that these effects have been reported as mild to moderate in some studies.^11,4

Finally, since cannabis is not legal in many locations, this makes research on its therapeutic effects challenging. It was only recently, in 2018, that doctors were given permission to prescribe cannabis-based medicines in the UK, and this is legal for certain conditions only. It is still rare for such treatments to be prescribed, which leads many patients to turn to obtaining cannabis illegally.

Summary

• MS is an autoimmune condition in which the myelin surrounding nerves is damaged, which can lead to symptoms of pain, muscle spasms, fatigue, and disturbed sleep, among others
• The usual treatments tend to not be effective enough at alleviating symptoms and are accompanied by unwanted and serious side effects. This is why many individuals with MS turn to cannabis, the recreational use of which is illegal in the UK
• Cannabis contains THC (psychoactive) and CBD (not psychoactive), which give this plant its therapeutic properties, including pain relief and antispasmodic effects
• Sativex is a treatment available in the UK for people with MS experiencing moderate to severe muscle spasticity. It is reported to be effective in many, but not all, for this purpose
• There is conflicting evidence regarding cannabis oil’s effectiveness in alleviating MS symptoms; however, research is limited in this area due to the varying legality of cannabis around the world