Thermal shock is a bit like asking your body to go from summer to winter in a fraction of a second. Do you step out of a sunbath and dive into ice-cold water? Do you leave a hot steam room and enter an air-conditioned room? These sudden transitions aren't just a simple “cool down”: they shake up your body, sometimes violently. Dizziness, chills, discomfort... your body doesn't like to be caught off guard. So how can you recognize heat shock, and more importantly, how can you avoid it? We explain everything.
Heat shock: definition and mechanisms
Heat shock refers to a sudden reaction by your body to a sudden change in temperature—often from a hot environment to cold water, or vice versa. The most common example? Swimming after eating or diving into ice-cold water in summer. The body undergoes significant stress, which can cause syncope, hydrocution, or even hypothermia if exposure is prolonged.
Terminology related to thermal shock
- Hydrocution: sudden discomfort in cold water, often after a meal or exposure to the sun.
- Hypothermia: a drop in body temperature below 35°C, common in very cold water.
- Hyperthermia or heat stroke: the opposite of hypothermia, this is when your body overheats.
Why is thermal shock dangerous?
In the event of thermal shock in water—for example, at the pool after eating or a heavy meal followed by a dip—your cardiovascular system is under stress. Your circulation is disrupted, your heart can race, and you can sometimes lose consciousness. It can also be the start of hypothermia if you stay in cold water for too long, or cause you to feel very unwell.
Symptoms to watch out for: heat shock or hypothermia?
Quickly identify the signs:
- Symptoms of heat shock: dizziness, feeling unwell, loss of consciousness immediately or within seconds.
- Symptoms of hypothermia: shivering, cold skin, numbness, confusion, slow breathing.
- Symptoms of hyperthermia: hot, dry skin, headache, nausea, rapid heartbeat, disorientation, high fever.
Beware of water shock after a meal
Jumping into the water right after eating can cause water shock. The body is already working to digest food (this is known as digestive heat) and cannot cope with the shock of cold water. The result: discomfort or worse. So take your time and allow your body temperature to return to normal.
How can you avoid thermal shock?
Warm up before diving in
Avoid sudden changes. Between hot and cold, make gradual transitions and allow your body to adapt
Have you just been sunbathing, running, or out of a sauna? Your body is in “boiling hot” mode. Plunging it straight into cool water risks thermal shock — or even hydrocution. To avoid this, bring your temperature down gradually:
- Stay in the shade or at room temperature for a few minutes before entering the water.
- Pour cool water over your arms, legs, and the back of your neck (yes, this old reflex is really useful).
- Enter the water gradually, especially if it is cold.
This adjustment period prevents your body from panicking and allows you to enjoy your swim safely.
Don't jump into the water after eating
Jumping into the water right after eating is a bad idea. Your body is in the middle of digesting: it is mobilizing energy to assimilate the meal. If you dive into cold water at this point, you risk immediate hydrocution. Wait at least 30 to 45 minutes after eating before swimming. This is a simple but essential reflex to avoid hydrocution after eating.
Hydrate and regulate your temperature
Drink before and after. A well-hydrated body reacts better to changes.
Wear the right clothes
Before and after going in the water, don't stay uncovered. Your body needs help regulating its temperature, especially if you've just been swimming or are exposed to the sun. Put on arm sleeves, a cooling T-shirt or even a cooling towel to avoid heat stroke and maintain a stable temperature. And don't forget your head: it's an area that's extremely sensitive to heat build-up. Wearing a lightweight hat, UV-protective cap or technical sun hat helps limit the risk of overheating, especially on the scalp, neck and face. The right accessory can often be the difference between a relaxing session and feeling unwell in 35°C heat!
What to do in case of heat shock or hypothermia?
- Get out of the water or away from the source of cold immediately.
- Lie down in a sheltered, warm, and quiet place.
- Warm up gently: put on dry clothes, wrap yourself in a blanket or warm towel, and drink a warm (not hot) beverage.
- Avoid any exertion and rest until the symptoms disappear.
- If you feel your condition worsening (confusion, dizziness, uncontrollable shivering), call for help or get someone to accompany you quickly.
G‑Heat: your ally against heat shock
Want to dive in, sweat it out, or cool off without risking heat shock? G-Heat is here to help. Our cooling range helps you maintain a stable body temperature during the summer heat. And when the cold returns, our heated clothing takes over to protect you from cold spells and the shock of low temperatures.
Whether you're facing a heatwave or an icy wind, G-Heat helps you stay in control of your temperature without compromising on comfort or style. Don't suffer from thermal shock anymore: anticipate, protect yourself, and enjoy every season to the fullest with G-Heat!
