The impact of heat on human health is often ignored when planning an overseas trip. Several recent global events provide good evidence of why this is foolish.

Temperatures soared at the Hajj in June this year. According to Human Rights Watch, more than 1,300 Muslim pilgrims were reported to have died due to heat-related illness. Multiple tourist deaths were also reported in an unusually early heatwave in Greece. The impact was notably on underprepared hikers, often elderly and possibly having pre-existing health issues.

Similar issues were reported in Asia, particularly South Korea and Japan. According to the Japanese, Fire and Disaster Management Agency, more than 37,000 people were treated for heatstroke during a record-breaking heatwave in July. In Tokyo, alone, more than 120 people died of heat-related illness.

What is heat-related illness?

Heat-related illnesses range from mild heat cramps to severe heat exhaustion or even life-threatening heat stroke. Educating yourself on the warning signs, staying hydrated and having a flexible itinerary could save your life while holidaying in hot climates. In other words, heat-related illnesses are very preventable.

Unfortunately, heat-related illnesses (HRI) are rarely discussed during pre-travel consultations where the focus is often on immunisations and medications. This often-overlooked hazard will become increasingly important as global temperatures increase. It must always be considered in any discussion on co-morbidities which might be impacted by heat.

What are the different types of HRI?

Extremely hot and humid weather can affect our body’s ability to cool itself. A significant rise in body temperature can lead to heat exhaustion, which can escalate to heat stroke, a medical emergency.

When the body experiences HRI, blood flow is redirected to the skin, resulting in cardiovascular stress. An increase in sweating can lead to dehydration. This can be life threatening if left untreated. It is important to be aware of the symptoms of HRI, how to manage and treat symptoms early, and what are the warning signs to seek urgent health advice, either at a local level or through your overseas health insurance.

Who is at most risk of HRI?

A study published in 2022 found the annual heat-related mortality of people over 65 years has increased by 68% over the last two decades. Exposure to high temperatures and high humidity, strenuous activities and insufficient hydration are some of the factors which increase the risk of HRI.

Travellers are very much at risk.

Those at the highest risk for serious HRI symptoms are:

• Those over the age of 65 years
• Young children and infants
• Pregnant women
• People with pre-existing medical conditions such as cardiovascular disease, high blood pressure, kidney disease, diabetes
• People taking medication for a mental health issue
• People taking other medications such as diuretics, beta blockers or central nervous system stimulants (ADHD)

Tips for staying safe in the heat

• Travel smart - follow health advisories, check the weather forecast and plan accordingly. Take regular breaks and have a flexible itinerary.
• Slowly acclimatise to heat - Give your body time to adjust to the heat gradually, especially if you are departing from a cooler climate. Gradually increase your exposure over several days.
• Avoid peak sun hours - Try to plan your activities around the heat and seek shade when the sun is at its highest.
• Stay hydrated - Aim for at least 2-3 litres of water each day. If you’re planning on outdoor activities or are sweating a lot, increase your fluid intake. Avoid excessive alcohol and caffeine, as they can lead to dehydration.
• Dress appropriately - Don’t forget to ‘slip, slop, slap’! Loose-fitting, light-coloured clothing is ideal. A hat, sunglasses and sunscreen of 30+ SPF or higher is recommended to avoid sunburn.
• Be mindful of vulnerable groups - Pay special attention to older people, children and those with chronic illnesses.

HRI Warning Signs

The Centre for Disease Control and Prevention (CDC) provides a list of HRI warning signs and recommended first aid steps. The advice covers the three main areas of concern, heat stroke, heat exhaustion and heat cramps.

Climate change must be considered in any discussion on future travel, as highlighted by the World Meteorological Organisation's report indicating that climate change indicators reached record levels in 2023.

Discover more about the impact of Extreme Weather on traveller health.