How heatwaves affect your blood pressure

The British Heart Foundation (BHF) says that around 3 in 10 people in the UK have high blood pressure (hypertension). It happens when the pressure on the walls of your blood vessels - caused by the blood within them - is higher than normal. Because they’re under more strain, your heart has to work harder, increasing the chance of heart disease, stroke, and other serious conditions.

So as temperatures rise, should you be concerned? Let’s take a look.

How heat can affect high blood pressure

While your body’s usually good at lowering blood pressure as a way to keep it safe when you overheat, there can be issues if it goes too far. Again, the additional strain on your heart as it beats faster to maintain blood flow into your organs means blood pressure can spike temporarily.

This happens when:

• Blood vessels widen - your body widens the blood vessels near your skin to cool you down. This is called vasodilation and allows blood to flow more freely.

• You sweat - this reduces blood volume, and your body might increase your heart rate as a response.

• Your body releases stress hormones - if you get too hot, parts of your nervous system release adrenaline, which shrinks your blood vessels and increases your heart rate.

• There’s an electrolyte imbalance - excessive sweating can reduce important minerals such as sodium, potassium, and magnesium, affecting your heart function.

• Medications have side effects - heat can increase the side effects of some medications. For example, some selective serotonin reuptake inhibitors and tricyclic antidepressants can affect your ability to sweat.

While sweating cools us down, it also means we lose water and electrolytes. Losing any type of fluid from your body reduces blood volume, which means blood pressure can drop, sometimes suddenly.

The most effective ways to stay safe are to keep hydrated and cool. You should also stay indoors between 11 am and 3 pm when the sun is at its most intense, wear light clothing, and limit strenuous activity.

Be more aware if you’re an older person, have a long‑term condition, or are taking blood‑pressure medication. Whether or not you belong to an at-risk group, there are some symptoms to watch out for that might mean you need some assistance.

Warning signs that your blood pressure may be affected include:

• Being light-headed or dizzy.

• Fainting or feeling faint.

• Rapid heartbeat.

• Nausea or headache.

• Muscle cramps.

• Excessive sweating or no sweating at all.

If you have any of these symptoms, act straight away to cool down and stay hydrated by getting out of direct sunlight and into somewhere cooler, cooling yourself down with cold - but not icy - water, and drinking plenty of non-alcoholic fluids.

If symptoms don’t go away, get help from a medical professional. Call an ambulance immediately if you or someone else becomes confused, stops sweating, loses consciousness, or collapses.