Why Do Heatwaves Make Your Sinuses Worse?
Updated: Aug 27
It's been hot. Maybe too hot here in the UK and it's doing a number on my sinuses, and I can imagine other sufferers are noticing the same increase in congestion, pressure and other symptoms. Unfortunately for us and planet Earth heatwaves are set to become a regular feature of UK Summers, this got me wondering whether there was any actual evidence linking hot weather and sinus problems and it turns out that there is.
A 2023 study found that exposure to extreme heat (defined as 35 degrees C) was associated with an increased risk of chronic rhinosinusitis symptoms. Interestingly, the research didn't identify a single cause but suggested that heat may trigger a cascade of environmental effect that can influence the nose and airways.
So, it's not just in our heads hot air really does contribute to symptoms and I know what you are thinking so, why does steam help? Well, we're not comparing like for like here. The reason steam helps is more to do with the added moisture rather than the hot air itself. While dry, hot outdoor air creates dehydration, increased allergens and environmental changes steam soothes and delivers moist air to the nasal passages, possibly improving the clearing mechanism by dampening down aggravating and inflaming debris, keeping the nasal lining hydrated and trapping any particles again, the research isn't clear but I think it makes sense.
Whilst on the topic of heat, I find personally, and this is my main tool when a big sinus headache strikes, that a hot compress really does soothe and dull the pain, although the line between pain relief and burnt forehead is a tricky line to tread! So, heat seems to be a blessing and curse for the sinus sufferer, especially outdoor heat which ties into more research into air pollution.
One explanation that I keep seeing is air quality and as an avid IQAir visitor (you can thank my environmental science degree for this) this caught my interest. The authors of a study, linked below, noted that higher temperatures may influence levels of fine particulate pollution known as PM2.5. Research has shown that PM2.5 can worsen allergic inflammation and damage the protective barrier lining the nose potentially making it more vulnerable to environmental irritants. However, once again, this hasn't been proven and using my personal experience I think allergens and other irritants aren't a trigger for all sinus sufferers in hot weather which leads me on to this interesting piece of research.
Another research paper which I have linked below looked into a nasal receptor called TRPM8. This receptor plays an important role in our perception of nasal openness. TRPM8 is activated when the lining of the nose cools slightly as air passes over the moist internal passage. The resulting signal tells the brain that air is flowing normally. This is how menthol products work, making us feel less congested despite air temperature, doing little to physically open the nasal passage. Menthol stimulates the same cooling receptors, basically tricking the brain into thinking more cool air is moving through the nose.
Could this have implications for hot weather?
It's possible. During a heatwave, the air entering the nose is warmer than usual. If the sensation of airflow depends partly on cooling, then warmer air may provide a weaker signal to TRPM8 receptors. In theory, this could contribute to a feeling of congestion even if the amount of airflow hasn't changed significantly.
At present this is only a hypothesis. I haven't found any studies directly testing whether heatwaves affect TRPM8 activity in sinus sufferers. However, it offers a compelling explanation for why some people report feeling more congested during periods of extreme heat it also raises the question that some sinus sufferers brains may interpret this sensation differently or more subtly or just in general may have damaged nasal receptors due to childhood injury or plate growth. I haven't found anything suggesting it but it makes you think!
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