Cannabis has been used for its medicinal properties for thousands of years. Over these years, it has been shown to aid in managing conditions like epilepsy and chronic pain.¹ Cannabis has also been used in the treatment of multiple sclerosis to help manage symptom exacerbations during relapses. 

A bit about multiple sclerosis

Multiple sclerosis, or MS, is a neurological autoimmune disease. MS causes the immune system to produce an inflammatory response to the myelin sheath, which is essentially a layer of fats and proteins responsible for insulating the nerves. Loss of myelin leads to the formation of plaque or lesions in the brain, which are areas of damage. This causes more inflammation and more damage, eventually resulting in neurodegeneration; the loss of neurons in the brain.² Multiple sclerosis presents as a set of symptoms that affect the whole body, but depend on where the damage has taken place in the brain.³ These include:⁴

• Fatigue 
• Muscle rigidity and spasms
• Weakness or numbness
• Lack of muscle coordination
• Chronic pain
• Problems with vision
• Sexual dysfunction
• Bladder and bowel dysfunction 
• Cognitive dysfunction 
• Depression

In the most common type of multiple sclerosis (relapsing-remitting MS), symptoms come and go. The disease onset consists of relapses (flare-ups or exacerbations) and remissions (periods of time with lesser or no symptoms). Relapses are associated with damage being done to the brain; hence, with every relapse, the disease can worsen.⁵ This means that, as multiple sclerosis progresses, relapses can increase in severity and become more and more difficult to manage. 

Currently, the management of relapse symptoms is the administration of corticosteroids or newer disease-altering therapies.⁶ Although these treatments have been shown to be successful, there is reason to seek alternative treatments. Firstly, corticosteroids are powerful medications, which are usually the last point of call in all fields of medicine, and are associated with severe side effects. Secondly, the wait for disease-altering therapies can take months. 

Cannabis and its components

Cannabis (also known as marijuana, weed or pot) is a plant which originates from Central Asia. It has a variety of structural and medicinal properties, which result in a variety of uses ranging from ropes and oils to recreational drugs. The chemicals that give cannabis its medicinally active properties are called cannabinoids. The two main types of cannabinoids are called tetrahydrocannabinol (THC) and cannabidiol (CBD). 

THC is the compound associated with the psychoactive effects of cannabis and is the compound responsible for getting its user “high”. CBD is not psychoactive. Both of these compounds have been shown to provide pain relief, be anti-inflammatory, prevent nausea/vomiting, control seizures and protect from neurodegeneration.⁷ This makes cannabis a good candidate in the management of multiple sclerosis relapses. 

Cannabis for symptom management of multiple sclerosis

The active compounds present in cannabis have a range of benefits, which can be helpful when addressing some symptoms of MS, particularly during relapses. Below is a summary of how cannabis can aid in the symptom management of multiple sclerosis. Please note that all outlined benefits and drawbacks should be taken with a pinch of salt as research on medical cannabis is limited (see ‘Considerations and risks’). 

Muscle spasticity

Multiple sclerosis causes loss and damage to neurons, which are responsible for the coordinated movement and activation of muscles. A hallmark symptom of MS is muscle spasticity, which refers to increased muscle tone caused by prolonged muscle contraction. The consequences of increased muscle spasticity are:⁸

• Muscle rigidity
• Involuntary spasms
• Loss of muscle coordination 
• Loss of mobility 
• Weakness or loss of muscle power

Cannabis has been historically shown to cause muscle relaxation and decrease bouts of muscle spasms.^9,10 Specifically in multiple sclerosis, there is evidence that medical cannabis is a promising agent in the management of muscle spasticity, with multiple groups of patients reporting an improvement in muscular symptoms following treatment with cannabinoids.^11,12 

Pain

Cannabis is also considered an analgesic (pain relief) drug. It has been used to relieve pain as far back as Ancient India and was introduced to Western medicine in the 19th century.^13,14 Medical cannabis has long been used in the treatment of chronic pain, even being used to replace opioids for pain management in some patients.¹⁵

Clinical trials have shown that cannabis can be effective in reducing the pain experienced by those suffering from multiple sclerosis.^16,17 

Sleep

Sleep quantity and quality are closely linked to all symptoms. For example, if an individual suffering from MS has extreme pain during a relapse, they will likely not be able to sleep well. Lack of sleep can then increase pain, making this a vicious cycle.¹⁸ 

Clinical trials have shown that cannabis products can improve sleep, decreasing sleep disturbances which arise from multiple sclerosis.^16,19,20 

Cognition

A lot of cannabis products are psychoactive, meaning that they change the way your brain works. Cognitive deficits are sometimes seen in patients with multiple sclerosis and are a result of brain damage. In users of cannabis without MS, cannabis has been shown to be detrimental to cognitive function. 

Researchers have found that cannabis also alters cognitive function negatively in those with multiple sclerosis in the long term.^21,22 However, other studies have shown that short-term cannabis use can even improve cognitive symptoms of MS in certain cases.²³ 

Cannabis use during multiple sclerosis relapses

Multiple sclerosis relapses are periods where the symptoms of the disease worsen. Cannabis can possibly be used to make these relapses more manageable, with symptom-specific relief. Furthermore, cannabis has also been shown to be anti-inflammatory in those with MS, meaning that it can potentially slow down the brain damage associated with relapses.²⁴ 

Research has also shown that cannabis can be neuroprotective. This means it can protect the brain from the loss of neurons.²⁵ This is significant in the study of multiple sclerosis, as MS is a neurodegenerative condition.  

Current research

Current clinical trials for the use of cannabis for the management of multiple sclerosis symptoms focus on either the two main cannabinoids (THC and CBD) or new chemicals derived from cannabis, which work on our cannabinoid receptors. This is done to maximise the beneficial effects of cannabis whilst keeping side effects as low as possible. Up-to-date clinical trials information can be accessed on clinicaltrials.gov. 

It should be noted that cannabis is not considered a treatment option, but may be helpful for some as an add-on to help manage symptoms during relapses. 

Considerations and risks

In the UK, medical cannabis is rarely prescribed by healthcare professionals. This is because of the limitations of previous research and the side effects of the drug. These are outlined below.  

Limitations of research 

Although cannabis has been shown to be beneficial in the symptom management of multiple sclerosis, research is very limited, as it remains illegal in many countries and research is restricted to small groups. This illegality means that researchers can study individuals who use illicit (illegal) cannabis, in which the chemical composition of the plant is unknown. 

The term cannabis refers to the genus of the plant. There are many species of the plant, with differing compositions of over 400 different chemicals.²⁶ This makes it impossible to generalise and standardise cannabis as one treatment. 

In addition to this, multiple sclerosis is a complex disorder of inflammation and neurodegeneration. A therapy that works for one individual may not work for another, and many treatments depend on many different variables, such as stage of disease, location of lesions or severity of symptoms.  

Side effects

The side effects associated with medical cannabis use are dependent on the chemical composition of the medication. These include:

• Decreased appetite 
• Diarrhoea
• Feelings nauseous or dizziness
• Feeling very tired or weak
• Change in mood or behaviour
• Hallucinations
• Suicidal thoughts 
• Psychosis 
• Dependence on the drug 

Summary 

Multiple sclerosis is a disease in which the body attacks parts of the nerves in the central nervous system. This leads to inflammation and neuron death. Multiple sclerosis presents itself differently for every individual suffering from it, but the most prominent symptoms include problems with muscle control or power, pain, fatigue or sleeping problems and cognitive impairments. In the most common form of multiple sclerosis, relapsing-remitting multiple sclerosis, these symptoms come in bouts called ‘relapses’. 

Cannabis can be used to help manage symptoms of multiple sclerosis, as it has been shown to provide pain relief, relax muscles and improve sleep. However, it is still unclear how cannabis affects the cognition of those with multiple sclerosis in the short and long term. Clinical trials currently are focusing on cannabis-derived chemicals, which can help improve multiple sclerosis relapse symptoms without the side effects observed with the use of medical or street-grade cannabis. In conclusion, cannabis can be useful in managing relapse symptoms of multiple sclerosis for some, but should not be treated as a cure or disease-altering treatment.