Blood pressure and heat

Summer, sun and sunshine put most people in a good mood. But not everyone enjoys very hot temperatures. When the thermometer rises above 25°C, it often puts strain on people with high blood pressure or with heart or lung disease.

Warm temperatures cause the blood vessels to widen and the blood pressure to drop. In some people this is so pronounced that the medication dose needs to be adjusted. Of course this should never be done on your own, but always in consultation with your treating doctor.

In the heat you also sweat more, which can upset the fluid balance. Mineralsespecially magnesium and potassium, which are important for proper heart functionas well as salt are washed out more in sweat. So not only does the bodys fluid volume decrease, the mineral balance can also be thrown off.

More important than ever for people with high blood pressure is the regular daily checking of blood pressure during the warm summer months. This lets you document whether and how much your blood pressure drops in the heat. And when the weather cools again, it gives you the information needed to know when its time to raise the medication dose back to the usual level. This is especially useful during prolonged heat periods.

Short-term large temperature swings of more than five degrees from one day to the next, on the other hand, increase the risk of a heart attack by about 60 percent for people with high blood pressure. Sudden heat also leads to more heart rhythm disturbances.

Medications and heat what should you watch for?

As mentioned at the start, the intake of certain medications may need to be adjusted for warm temperatures. This must always be discussed with your treating doctor.

People taking diuretics, for example, should watch themselves particularly closely. Because these drugs cause fluid loss, the additional sweating in summer heat can drain too much fluid from the body. Its advisable to talk with your doctor about a possible dose reduction.

ACE inhibitors and sartans (angiotensin receptor blockers) can sometimes reduce the feeling of thirst. This is not fully settled, but we mention it because its especially important to drink enough in warm weather.

The Robert Koch Institute (RKI) published a report in September 2023 that highlights, in addition to diuretics, other blood-pressure-lowering medications because they can cause problems in the heat. These include beta blockers, ACE inhibitors, sartans (angiotensin receptor blockers), calcium channel blockers, clonidine and moxonidine. Here too, its advisable to discuss with your treating doctor whether a change in how you take these drugs is recommended. Listed heat-related side effects include:

On the one hand, prevention of dilation of blood vessels (beta blockers) in the skin reduced heat loss by convection, increased threshold for sweat secretion (central antihypertensives); on the other hand, amplification of the blood-pressure-lowering effect through vasodilation drops in blood pressure

Even people who do not need medication for blood pressure can notice changes in their readings in hot weather. Normal or high-normal blood pressure can fall because of vessel widening and the reduced fluid volume from sweating. Dizziness, circulatory problems, lightheadedness, headaches and nausea are possible consequencessometimes it even leads to fainting.

The best way to counter this is to drink enough fluids. Mineral water or diluted fruit spritzers work well to help keep mineral levels balanced. If you are allowed to drink only a limited amount per day because of an illness, you should also discuss this with your doctor.

Very cold drinks actually cool you less effectively than lukewarm ones, because the body responds to sudden strong cooling with an increase in blood pressure and you may end up sweating more afterward. The same applies to showersbetter lukewarm than ice-cold.

On hot days, people with high blood pressure can have a little more salt than usual, because sweating causes the body to lose salt.

Take it easy on hot days. Wear airy clothing that lets your skin breathe. If possible, stay in cool rooms, but be cautious with air conditioning. If a room is cooled too much, the shock when you leave the room will be even greater.

Your workout should be moved to the morning when the air is still fresh and the heat isnt as strong yet.

You can take a cue from countries used to the heat. They take a midday siesta and life happens in the mornings and evenings.

A 2023 study provided interesting insights into how to tell whether the body is under heat stress or about to be. It was observed that the participants heart rate rose about 20 minutes before their bodies could no longer maintain a stable core temperatureeven though they were not physically exerted. Heart rate can therefore be an indicator that you are entering heat stress and may need to look for ways to cool down.

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This article comes from BloodPressureDB – the leading app since 2011 that helps hundreds of thousands monitor their blood pressure every day. Our content is based on carefully researched, evidence-based data and is continuously updated (as of 06/2024).

Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as in outpatient care, and has led BloodPressureDB's specialist editorial team since 2015. Thanks to her extensive additional qualifications as a paramedic, first responder and in various therapy and emergency areas, she provides solid, practical and reliably reviewed information.

Blood pressure and heat

Medications and heat what should you watch for?

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