Blood Pressure and Heat

Summer, sun, and sunshine bring good mood to most people. However, not everyone is happy about high summer temperatures. When the thermometer rises above 25 degrees, it often burdens people suffering from high blood pressure or a heart or lung disease.

Due to the warm temperatures, blood vessels expand and blood pressure drops. For some, this is so pronounced that the medication dosage needs to be adjusted. Of course, this should never be done on one's own initiative but must always be discussed with the treating physician.

In the heat, one also sweats more, which can disrupt the fluid balance. Minerals - especially magnesium and potassium, which are important for proper heart function - as well as salt are increasingly washed out with sweat. Thus, not only does the fluid volume in the body decrease, but the mineral balance can also become unbalanced.

More important than ever for high blood pressure patients during the warm summer months is the regular daily measurement of blood pressure. This allows one to document whether and how much their blood pressure drops in the heat. But even when the weather becomes cooler again, this way one gets the necessary information about when it is time to increase the medication dosage back to normal levels. This is particularly interesting during longer heat periods.

Short-term strong temperature fluctuations of more than five degrees from one day to the next, on the other hand, increase the risk of heart attack for people with high blood pressure by about 60 percent. Due to the sudden heat, heart rhythm disturbances occur more frequently.

Medications and Heat - What Should Be Considered?

As mentioned at the beginning, the intake of certain medications should possibly be adjusted to the warm temperatures. This must always be done in consultation with the treating physician.

People who take diuretics to treat their high blood pressure should particularly monitor themselves. Since these medications have a diuretic effect, excessive sweating in the summer heat can lead to too much fluid being removed from the body. Here, a conversation with the treating physician about a possible dose reduction is advisable.

ACE inhibitors and sartans may reduce the feeling of thirst. This is not entirely clarified, but we would like to point it out, as it is important to drink enough, especially in warm temperatures.

The Robert Koch Institute (RKI) published a report in September 2023 that highlights not only diuretics but also other blood pressure-lowering medications, as these can cause problems due to heat. Mentioned are beta-blockers, ACE inhibitors, sartans, calcium antagonists, clonidine, and moxonidine. Here, too, it is advisable to discuss with the treating physician whether a change in intake is advisable. A side effect triggered by heat is indicated:

On the one hand, prevention of the expansion of blood vessels (beta-blockers) in the skin → heat dissipation through convection is reduced, increase of the sweat secretion threshold (central AHT); on the other hand, enhancement of the blood pressure-lowering effect through vasodilation → blood pressure drops

However, even people who do not require medication for blood pressure can feel the change in values at summer temperatures. Because even normal or high-normal blood pressure values can drop due to the expansion of blood vessels and the reduced fluid volume (due to sweating). Dizziness, circulatory problems, faintness, headaches, and nausea are possible consequences - sometimes even leading to a circulatory collapse.

This can best be counteracted by adequate fluid intake. Mineral water or diluted fruit juices are good to maintain a balanced mineral balance. Those who are only allowed to drink a certain amount per day due to a medical condition should also consult their doctor in this case.

Ice-cold drinks actually cool less effectively than lukewarm ones, as the body reacts to the sudden strong cooling with an increase in blood pressure, and one tends to sweat more afterwards. The same applies to showering - better lukewarm than ice-cold.

On hot days, it is also okay for high blood pressure patients to have a bit more salt than usual, as the body loses salt through sweating.

Take it easy on hot days. Wear loose clothing that allows air to circulate around the skin. If possible, stay in cool rooms, but be cautious with air-conditioned spaces. If it is cooled too much, the shock when leaving the room is even greater.

Your workout should be scheduled for the morning when the air is still fresh and the heat is not too intense.

One can take an example from heat-acclimatized countries. Here, a siesta is taken at noon, and life takes place in the morning and evening hours.

Interesting findings on how to recognize whether the body is stressed by heat or will soon be stressed were provided by a study published in 2023. It was observed that the heart rate of the subjects increased about 20 minutes before the body was no longer able to maintain its core temperature. This occurred without any physical exertion. The pulse rate can thus be an indicator of when one is entering heat stress and may need to seek cooling.

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By Sabine Croci. This article is medically reviewed. Last updated by Sabine Croci (06/2024).
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Blood Pressure and Heat

Medications and Heat - What Should Be Considered?

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