Attitudes towards cannabis are changing – and not just among the public. A growing number of countries are gradually loosening restrictions on cannabis-based products for both medicinal and recreational purposes. But with access to cannabis on the rise, it’s important to understand the true implications of its use, particularly among those with existing health conditions such as asthma. So, let’s take a closer look at what we know about the relationship between cannabis and asthma.
What is asthma?
Asthma is a common lung condition that can cause breathing difficulties and other symptoms. It is caused by inflammation in the tubes that carry air to and from the lungs, causing them to temporarily narrow and become more sensitive. Generally, the condition is treated with inhalers which deliver medication directly to the lungs. These can be preventer inhalers which are used every day to prevent symptoms or reliever inhalers which are used to relieve symptoms.
The exact cause of asthma can vary, with some people having specific triggers and others experiencing symptoms randomly. Common triggers may include allergies, exercise, infections (e.g., cold and flu), smoke and pollution. Identifying and avoiding these triggers can be vital for keeping symptoms under control and preventing the condition from worsening.
Cannabis allergies and asthma
We don’t often hear about cannabis allergies in the same sphere as hay fever or peanut allergies; however, that isn’t to say they don’t exist – in fact, cannabis allergies are likely much more common than you think.
While the exact prevalence of cannabis allergies is unknown, a 2019 survey of 107 patients in a Toronto allergy clinic found that 24 (52.2%) active users, 15 (24.6%) previous users, and 3 (4.2%) non-users of cannabis attributed symptoms to cannabis exposure, including respiratory, ocular, dermatologic, and gastrointestinal symptoms. These findings indicate that hypersensitivity to cannabis may be relatively common in patients with other allergies; however, validated testing is required to confirm these results.
Nonetheless, it is acknowledged that exposure to cannabis can trigger familiar responses in people who are allergic to the plant, including sneezing, itching, watery eyes and, of course, breathing problems. Cannabis allergies can trigger asthma attacks in the same way as any other allergen, causing symptoms to flare up suddenly. In more severe cases, exposure to cannabis could even trigger anaphylaxis.
Cannabis smoke and asthma
Cannabis is a versatile plant that can be consumed in many different ways; however, despite its health implications, smoking is by far the most popular method of consumption. A recent survey found that this was also true among individuals with asthma. In 2021, The Allergy & Asthma Network teamed up with the Canna Research Foundation to identify cannabis attitudes and patterns of use among those with asthma. They found that, of 489 respondents, 18% currently used cannabis, with over half of those (53.4%) smoking the drug. A further 35.2% of users reported vaping cannabis.
It’s a widely accepted fact that inhaling smoke of any kind can expose our bodies to harmful compounds, including toxins and carcinogens. While some studies have shown that cannabis use doesn’t carry the same risks as tobacco use, its smoke can cause irritation to the respiratory system even in healthy individuals. Furthermore, numerous studies, including a 2007 systematic review, have implied a link between long-term cannabis use and increased respiratory symptoms, including cough, phlegm, and wheezing. Current evidence also suggests an association between cannabis use and bronchial asthma, though further studies are needed to clarify this link. However, some studies have also identified an association between short-term cannabis administration and bronchodilation…
Could there be any benefits?
A number of the cannabinoids found in cannabis have known anti-inflammatory properties, leading some to wonder whether the plant could actually relieve some asthma symptoms. The previously mentioned study is not the only one to assess cannabis’ potential as a bronchodilator – that is, a substance that can relax the muscles in the lungs and widen the airways, making breathing easier. Other types of bronchodilators such as beta-2 agonists, anticholinergics, and theophylline are actually used as asthma medications administered with inhalers.
Another review, published in 2020, aimed to review the known effects of medical cannabis in asthmatic patients. The authors concluded that cannabis has a bronchodilator effect on the airways and might have anti-inflammatory effect on asthmatic patients. However, they also note that smoking cannabis was linked to harmful effects on the lungs, including airway irritation and the development of chronic bronchitis.
While the current evidence demonstrates that THC and potentially other cannabinoids may have a positive effect in soothing inflammation in the lungs and airways, many clinicians agree that it is unlikely to be of therapeutic value in asthma treatment, “since its bronchodilator action was mild and inconsistent.”
Can medical cannabis be prescribed to patients with asthma?
Current evidence is something of a mixed bag when it comes to cannabis and asthma. Having said that, it is pretty clear that smoking cannabis – and any other substance, for that matter – can aggravate asthma and potentially lead to a worsening of symptoms and the occurrence of asthma attacks. So, with all this considered, can medical cannabis be prescribed to patients with asthma?
Medical cannabis can come in a variety of forms. While this does include cannabis flower – which is recommended to be administered using a vaporiser as opposed to smoking – other alternative methods such as oral sprays, capsules, and oils are also common. Due to the potential bronchodilator effects of cannabis, it could be theorised that such products may be useful in the treatment of asthma; however, the decision to prescribe cannabis-based medicines for any condition in the UK must be taken by a specialist clinician with knowledge in this area, and there are many patients being prescribed cannabis who have some form of asthma. It is always recommended that you speak with your doctor if you are considering using cannabis as a treatment for any condition or symptom.
For more information on accessing a medical cannabis prescription in the UK, read the leafie guide.