For many people, hot weather means finding a cool place, drinking more water and staying out of the sun. For people with heart problems, however, summer can require a little more care.

Sweating, fluid loss and an increased heart rate are normal responses to heat, but they can create problems for people with coronary artery disease, high blood pressure, heart failure or rhythm disorders.

Enes Çelik, a cardiologist at Bilecik Şeyh Edebali University, said the effects of hot weather can vary depending on a patient's condition.

"Heat brings different mechanisms to the forefront depending on whether a person has coronary artery disease, hypertension, heart failure or an arrhythmia,” Çelik said.

When temperatures rise, blood vessels near the skin widen and sweating increases. Losing too much fluid can reduce blood volume and cause electrolyte changes.

For people with coronary artery disease, this can put additional strain on the heart. A faster heart rate increases the heart's need for oxygen, while dehydration and low blood pressure can reduce blood flow to the heart muscle.

People who have recently had a heart attack need to be particularly careful with exercise during very hot weather.

"A patient may feel well, but that does not mean they should immediately return to their previous level of exercise,” Çelik said.

He recommends exercising during cooler hours and gradually increasing activity, especially during the first few weeks after a heart attack.

"Chest pain, pressure, new shortness of breath, excessive sweating, marked fatigue, palpitations or a feeling of faintness should not be ignored,” he said.

Blood thinners, cholesterol medication and other prescribed drugs should also not be stopped when the weather is hot.

Heat affects blood pressure

Hot weather can cause blood pressure to fall, especially in people taking several medicines for hypertension.

Heavy sweating and not drinking enough water can cause dizziness or weakness. In some cases, reduced blood flow to the kidneys can also become a problem.

But a lower blood pressure reading does not mean patients should reduce their medication on their own.

"‘Summer has arrived, my blood pressure has dropped, so I’ll reduce my medication by half’ is not the right approach,” Çelik said.

If a person develops dizziness, weakness or blurred vision during a heat wave, he recommends checking blood pressure at home in the morning and evening and keeping a record. Kidney function and sodium and potassium levels may also need to be checked before a medication dose is changed.

For people with heart failure, the balance can be even more difficult.

These patients can lose a lot of fluid through sweating, while diuretics, commonly known as water pills, can increase fluid loss. This may lead to low blood pressure, kidney problems and electrolyte changes.

But stopping or reducing a diuretic without medical advice can cause fluid to build up again, leading to swelling, shortness of breath and, in some cases, hospitalization.

This is why the common advice to "drink plenty of water” does not apply to every heart failure patient.

"Fluid intake should not be the same for everyone,” Çelik said. "It should be decided according to the patient's condition, including fluid buildup, kidney function and sodium levels.”

During very hot periods, patients with heart failure may also need to keep a closer eye on their weight, blood pressure, pulse, swelling, breathing and urine output.

Heat can affect young people too

Older people and those with heart or kidney problems are among the groups most at risk in extreme heat. But young and otherwise healthy people can also run into trouble.

Long periods in the sun, heavy exercise or hard physical work can lead to severe dehydration, fainting or heatstroke. High humidity, alcohol and energy drinks can add to the problem.

"Risk increases with age, but it is not limited to older people,” Çelik said.

Healthy people can continue exercising during the summer, but the time and intensity matter. Çelik recommends exercising in the early morning or evening rather than during the hottest hours.

"Dizziness, nausea, unusual tiredness, chest pain, shortness of breath or strong palpitations are signs that it is time to stop,” he said.

Energy drinks are another concern, particularly before exercise. Their high caffeine content and other stimulants can raise heart rate and blood pressure and may trigger palpitations or rhythm problems. Heat, dehydration and intense exercise can add to the strain.

People with hypertension or known rhythm problems should be particularly careful with energy drinks, Çelik said.

Alcohol can also affect the body's fluid balance.

"Drinking alcohol to cool down is not the right approach,” Çelik said.

He added that ordinary coffee should not automatically be treated in the same way as high amounts of caffeine from energy drinks. Water should remain the main source of hydration.

Heat or something more?

Some common ideas about summer and heart health can also be misleading. A drop in blood pressure does not automatically mean medication should be reduced, while someone with heart failure should not assume that drinking as much water as possible is always better.

The most important point, he added, is not to blame every unusual symptom on the weather.

"A faster heartbeat after walking in the heat may not be unusual. But fainting, repeated dizziness, severe shortness of breath, chest pain or prolonged palpitations are different,” he said.

"Chest pain, severe shortness of breath, fainting or prolonged palpitations should not be dismissed by saying, ‘It’s just the heat.’”