The common cold is a viral, highly contagious illness, which is more likely to affect people during the winter months. Responsible for a range of symptoms including dry or chesty cough, runny or congested nose, sore throat, fever, and fatigue, the common cold is not caused by just one virus. Instead, it is associated with as many as 200 different strains.
One type of virus particularly associated with the common cold is the rhinovirus with “rhino” meaning “nose”, this literally just means “nose-virus”! There are three main species of rhinovirus, and at least 99 different serotypes strains As well as rhinovirus, the common cold is also associated with various strains of coronavirus, adenovirus, enterovirus, and influenza virus. Most common colds are caused by different types of rhinovirus.
Cold viruses are passed from person to person by hand-to-hand and hand-to-surface contact, as well as airborne transmission of viral particles. Hence, it’s important to cover the mouth or nose while coughing or sneezing, and to wash hands regularly!
Once a cold virus has infected a human host, it gets to work – infiltrating the mucous membranes of the nose, mouth and throat, and reproducing rapidly. For the most part, cold viruses such as rhinovirus don’t cause any particular damage to the body – they simply cause an immune response as the body recognises unwanted invaders exploiting its resources. But for immunocompromised people, or individuals suffering from asthma or COPD, catching a cold can be seriously bad news.
Many rhinovirus serotypes bind to an immune protein known as intercellular adhesion molecule 1 (ICAM-1). This protein is present on the outer cell membrane of certain epithelial cells (which make up the upper layer of the mucous membranes); the rhinovirus essentially hijacks it to gain entry to the interior of the cell. Once the virus has gained entry to its first host cell, it can take control of the cell and hijack its reproductive system in order to reproduce itself!
Usually, ICAM-1 helps cells adhere (stick together), particularly after injury or stress. But when it gets hijacked by the rhinovirus, it sparks off a release of pro-inflammatory cytokines (cell signalling proteins), which leads to inflammation of the mucous membranes of the throat and nose. This inflammatory response is key to the congested and sore feeling associated with having a cold. For most people, that’s pretty much the worst of it – but it can lead to severe complications, including pneumonia, for certain individuals.
Relation between cannabinoids and ICAM-1
The endocannabinoid system is now well-known to be deeply involved with the immune system, and cannabinoids have been repeatedly demonstrated to cause complex immunological effects. But when it comes to ICAM-1, there is sparse research available, and apparently nothing on the direct relationship between cannabinoids, ICAM-1 and rhinovirus.
There is evidence that cannabinoids can have an effect on ICAM-1 expression levels in certain situations. One study reveals that CBD and THC can both cause increased expression of ICAM-1 on breast cancer cells, which leads to an increased rate of cell “lysis” (cell death via disintegration of the membrane).
This may be good news for cancer research, but increased expression of ICAM-1 is certainly not what one needs when trying to prevent a rhinovirus from taking hold. In fact, there is evidence that rhinovirus can increase the expression of ICAM-1 in order to provide itself more hijacking opportunities! However, perhaps more useful is the discovery that certain cannabinoids can reduce the expression of ICAM-1 in other situations.
For example, the synthetic cannabinoid R(+)WIN 55,212-2 may indirectly block the expression of ICAM-1 by blocking the activity of interleukin-1, another important immunological protein. This particular study investigated MS and how cannabinoids can help slow its progression – and intriguingly, there is a growing body of evidence suggesting that rhinovirus could be instrumental in the pathogenesis (development) of MS.
Clearly, there is still much to learn about the transmission and pathology of rhinovirus and other types of common cold virus – as well how all this relates to chronic autoimmune disorders like MS. But it’s clear that the endocannabinoid system is fundamentally involved, and there may be potential for certain cannabinoids to help prevent the transmission of rhinoviruses in certain situations, by reducing the expression of ICAM-1.
So How Can Cannabis used as a remedy to treat coughs and colds?
Despite all our best efforts, and no matter how healthy we are, it’s almost inevitable that sooner or later one of those 200 viruses is going to overcome the body’s defense systems and cause a cold or cough. When that happens, there’s not a whole lot that can be done to actually cure the illness – cold viruses are so numerous and so quick to mutate that developing effective antivirals and vaccines is all but impossible.
So when we catch cold, it is pretty much inevitable that we will have to let the virus run its course, and that we will feel significantly subpar for several days. But there are various ways in which we can ease the symptoms of colds and coughs – honey, salt-water gargles, saline drips, ibuprofen, or paracetamol may confer antiseptic, analgesic or anti-inflammatory benefits, for example.
So what about cannabis? There’s plenty of evidence that various compounds in cannabis have anti-inflammatory and analgesic effects. THC, CBD, CBC and CBG are all known to exert varying degrees of anti-inflammatory and analgesic action, and there are plenty of terpenes and terpenoids in cannabis with similar properties, such as linalool, limonene and eucalyptol.
As well as this, various cannabinoids and terpenoids are known for their relaxing, anti-anxiety or sedative effects. During times of illness, such properties may be very useful in increasing subjective feelings of wellbeing. Furthermore, common colds can also cause appetite loss in some people, and THC in particular has been repeatedly demonstrated to have appetite-stimulating properties.
How to use cannabis when you feel cold?
When we catch cold, we are likely to experience nasal congestion and sinus pain, sore throat, dry or chesty cough, and irritated eyes and none of these symptoms are improved by smoking of any substance. Even vaping or dabbing will probably exacerbate sore throats and coughs even if these methods are usually not as hot or as harsh as smoking itself.
For this reason, it’s best to stick to edibles, topicals, and anything else that doesn’t cause irritation to the throat and lungs. Hard candies infused with CBD or THC can help soothe throat inflammation and soreness. At least one US company, Jolly Meds, offers THC-CBD lozenges with added menthol and eucalyptus oils for added soothing and decongestant effects. Cough drops infused with cannabinoids and terpenoids may bring relief.
Another method that many people report to provide subjective relief is cannabis tea. Teas and herbal infusions can offer soothing, warming and comforting relief from cold and cough symptoms, and when cannabis extracts are added, they may provide extra help in the fight against inflammation and pain.
There are various ways to make cannabis tea, but the general idea is to ensure that at least some fat or oil is used, in order to allow the cannabinoids to dissolve and infuse through the mixture. Hot water alone will not dissolve cannabinoids. Therefore, making some cannabutter or cannabis-infused milk and adding that to a hot-water infusion will yield improved results. As well as cannabinoids themselves, various other plant compounds could provide benefits if infused into tea. For example, tea (particularly green tea) contains catechin flavonoids, which have been found to be beneficial against cold and flu viruses. Many people find that cannabis tea helps during a cold.
Echinacea, Endocannabinoids and Rhinovirus
Interestingly, valuable insight into the endocannabinoid system’s response to rhinovirus comes from research into a plant that isn’t even cannabis – echinacea, which contains compounds known as alkylamides that bind to both the CB1 and CB2 receptors. There is even some evidence that these natural “cannabimimetic” compounds exert a directly antiviral effect, reducing the duration of symptoms by up to four days. Echinacea has been demonstrated in clinical trials to significantly reduce the severity and duration of common cold symptoms. There are various compounds in the plant thought to have an effect, including cichoric acid (a natural antioxidant), various polysaccharides, and the aforementioned alkylamides.
Echinacea’s biological activity is complex and still not fully understood, and it has been shown that the active compounds within it work in ways that may be either CB receptor-dependent or independent. But what is certain is that the endocannabinoid system is fundamentally involved.
In one 2009 study, echinacea extracts high in alkylamides were shown to cause a reduction in the pro-inflammatory cytokine, tumor necrosis factor A (TNF-α), and an increase in the anti-inflammatory cytokine interleukin-10 – through activation of the CB2 receptors.
Furthermore, this study suggested that root and leaf extracts, which contained different alkylamide profiles, were more effective in combination than alone, suggesting that echinacea has an “entourage effect” of its own.
Therefore, use of both cannabis and echinacea extracts can benefit people suffering from coughs and colds, in various complex ways that are yet to be fully researched. Although the common cold is generally not a serious risk to health, it is nonetheless responsible for up to 40% of employee absences from work due to illness in the US, and throughout the world, billions of dollars are spent each year on remedies that may be of little to no effectiveness. We have a lot left to learn about how these complex biological mechanisms interact and exert their effects, but as time goes on, it’s increasingly clear that we need to completely rethink plant medicine and radically reassess its potential contribution to human health.