Travelling During a Heatwave: What to Pack and Risks to Prepare for

Heat does not just dehydrate you. It degrades your medications, blunts your body's cooling system, and overwhelms local emergency services. Here is how to prepare.

Heatwave travel: the medication risk nobody talks about

Most travellers prepare for heat by packing sunscreen and a reusable water bottle. Few check whether their daily medications interact with high temperatures. That gap is where heat-related illness becomes a medical emergency.

This guide covers what heatwaves do to your body and your drugs, what to pack, and what to do if things go wrong abroad.

Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Regulations, drug availability, and healthcare protocols change. Always consult your prescribing clinician or pharmacist before travelling, and verify current rules with the relevant national health authority.

Why heatwaves are more dangerous when you take regular medication

A 2020 study found that commonly prescribed drugs interfere with the body's ability to perceive and protect itself from heat, raising the risk of hospitalisation. The drugs on that list are not niche. They include diuretics, beta-blockers, antipsychotics, antihypertensives, anticholinergics, and stimulants such as methylphenidate.^[1]

The mechanisms vary by drug class. Diuretics such as furosemide and hydrochlorothiazide increase urination, which can lead to dehydration and electrolyte imbalance when fluid losses from sweating are already high. Beta-blockers such as metoprolol and propranolol decrease blood flow to the skin, which impairs sweating. Anticholinergics and older antihistamines block sweat gland function directly.^[2]

The highest risk comes from combinations. The US CDC identifies ACE inhibitors or ARBs taken alongside diuretics as carrying additive risk of dehydration, dizziness, and kidney injury in heat. If you take this combination, discuss heat precautions with your prescriber before you leave.^[3]

Heat also degrades the medications themselves

The physical stability of a medication is a separate problem from its pharmacological interaction with heat. Insulin, biologics, and epinephrine auto-injectors are the most vulnerable. Emergency auto-injectors like EpiPens can be compromised by high temperatures, with the device potentially delivering an incomplete dose. Keep them in an insulated pouch, away from direct ice contact.^[4]

Solid oral medications degrade too. Tablets can discolour, crack, or fuse together. A strange odour from a blister pack is a sign the active compound has broken down. When in doubt, do not use a medication that has been left in a hot car or a sun-facing bag, and seek a replacement.

If you rely on any cold-chain medication, plan your cold storage for every leg of the journey, including airport transfers, bus rides, and beach days. A purpose-built medical cooling wallet with a phase-change insert maintains 2-8°C for 12 to 48 hours, depending on ambient temperature.

What to pack before a heatwave destination

A medication review appointment. Book this two to four weeks before travel. Ask your prescriber specifically whether any of your medications affect sweat production, fluid balance, or body temperature regulation.

Oral rehydration sachets. Sports drinks replace some electrolytes, but clinical oral rehydration salts (ORS) are more effective at replacing sodium and potassium lost through sweat. Pack at least five sachets per person per week in heatwave conditions.

You can read more about how oral rehydration salts differ from standard sports drinks in terms of electrolyte composition and clinical use.

A digital thermometer. You need to distinguish heat exhaustion from heatstroke in the field. A core temperature above 40°C (104°F) with confusion signals heatstroke, which is a medical emergency requiring immediate cooling and emergency services.

A cooling towel or spray bottle. Applying cool water to exposed skin accelerates the body's surface cooling. In the absence of ice or air conditioning, this is your first-line physical intervention.

Your complete medication list in your International Patient Summary. Local emergency clinicians abroad need to know exactly what you take before they treat you for heat illness. Drug interactions, contraindicated cooling agents, and IV fluid choices all depend on your medication history.

Sufficient supply with buffer stock. Heatwaves strain local pharmacies. Greece experienced mandatory work-cessation orders during its 2025 heatwave, and pharmacies in Italy, Turkey, and Cyprus also faced disruption from the same heat event. Carry extra days of supply for every prescription medication.

Recognising the difference between heat exhaustion and heatstroke

Heat exhaustion and heatstroke are not the same thing, and treating one as the other wastes critical time. Heat exhaustion does not usually need emergency medical help if you can cool down within 30 minutes. Heatstroke does. It requires emergency services immediately.^[5]

Heat exhaustion presents with heavy sweating, headache, dizziness, nausea, fast heart rate, and muscle cramps. The person is conscious and oriented.

Heatstroke adds confusion, slurred speech, or loss of consciousness, with a body temperature typically above 40°C. This is a life-threatening emergency and you must seek emergency assistance without delay. Do not try to manage it yourself.^[6]

What to do if you get sick abroad during a heatwave

For heat exhaustion: move the person to a cool place immediately. Remove unnecessary clothing. Give plenty of water or an isotonic sports drink to replace salt lost through sweating. Fan the skin or apply a cool, wet cloth. If symptoms do not improve within 30 minutes, escalate to emergency services.^[7]

For heatstroke: call the local emergency number immediately. In Greece and Italy, that is 112. In Thailand, it is 1669. In Australia, it is 000. While waiting for help, cool the person actively: wrap them in a cool, wet sheet and fan them.

Local emergency departments in heatwave-affected destinations fill up rapidly. In Greece during the July 2025 heatwave, authorities issued mandatory outdoor work bans, and hospitals in Athens reported elevated admissions. If the nearest emergency department has a long queue and symptoms are worsening, ask emergency dispatch for advice on the nearest available unit.

Behaviour changes that matter more than any gadget

The UK's National Travel Health Network and Centre (NaTHNaC) advises travellers to stay out of the sun at its hottest, typically between 11 am and 3 pm. This is the single most effective behavioural change for reducing heat illness risk in heatwave conditions.^[8]

Schedule strenuous activity for before 9 am or after 6 pm. Plan museum visits, transport connections, and pharmacy runs for midday. Avoid alcohol in the afternoon, as it acts as a diuretic and compounds fluid loss.

Thirst is a lagging indicator. By the time you feel thirsty, you are already mildly dehydrated. Drink at least 500 ml of water per hour during outdoor activity in temperatures above 35°C, more if you take diuretics or anticholinergic medications.

Your medical records could save your life in a foreign emergency room

Heat illness can cause confusion quickly. An unconscious traveller cannot explain their medication list to a treating clinician. A doctor who does not know a patient is on lithium or an ACE inhibitor and a diuretic will not anticipate the specific electrolyte and kidney risks in that person's presentation.

Nomedic stores your International Patient Summary (IPS), including your full medication list, allergies, and conditions, in a format that emergency clinicians anywhere can read. A QR code on your phone or a printed card gives an A&E team immediate access without you needing to say a word.

Build your IPS before you leave, not after something goes wrong. Include every medication, the dose, and the prescribing clinician's contact. It takes ten minutes and removes a significant risk from your trip.

Frequently asked questions

Can my regular medication make me more likely to get heatstroke?

Yes. Diuretics, beta-blockers, anticholinergics, antipsychotics, and some antidepressants all interfere with the body's ability to sweat, regulate fluid balance, or sense thirst. If you take any of these, discuss heat precautions with your prescriber before travelling to a hot destination. Do not adjust doses yourself without clinical guidance.

Is heat exhaustion dangerous enough to go to hospital abroad?

Mild heat exhaustion can be managed without hospital care if the person cools down and recovers within 30 minutes of rest, cooling, and rehydration. If symptoms persist beyond 30 minutes, or if confusion, slurred speech, or loss of consciousness develops, these are signs of heatstroke and require immediate emergency care.

What is the emergency number for heat illness in Greece, Italy, and Thailand?

Greece and Italy both use 112 as the universal emergency number. In Thailand, call 1669 for emergency medical services. Always confirm the local emergency number before you arrive at your destination, as some countries use separate ambulance numbers.

How do I keep insulin cool during a heatwave trip when there is no fridge?

A phase-change medical cooling wallet maintains 2-8°C for 12 to 48 hours without a power source. Avoid direct ice contact with insulin vials or pens, as freezing destroys the medication. Do not leave insulin in a car, a beach bag in the sun, or near air-conditioning vents that switch off overnight.

Do heatwaves affect medication availability at pharmacies abroad?

Yes. During severe heatwaves, pharmacies and hospitals in affected destinations see surges in demand and can face supply shortages. Greece, Italy, and Turkey all experienced healthcare pressure during the summer 2025 heatwave. Carry a full supply of your prescription medications with several days of buffer stock.

Can I drink alcohol to cool down during a heatwave?

No. Alcohol acts as a diuretic and increases fluid loss, which compounds dehydration in hot weather. It also impairs your ability to recognise heat illness symptoms in yourself or others. Stick to water and electrolyte solutions during heatwave conditions.