Coffee and Blood Pressure: What you need to know

Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps blood through your body. Blood moves oxygen and nutrients around the body. To help it move, it needs some pressure.

Blood pressure is measured in millimetres of mercury (mmHg). It’s always given as 2 numbers, which looks like 120/80 mmHg.

The top number is Systolic Blood Pressure. This measures the pressure in your arteries when your heart beats and contracts to pump blood.

The bottom number is Diastolic Blood Pressure. This measures the pressure in your arteries when your heart is at rest between beats.

High blood pressure is often called the “silent killer” because it can damage your body without causing obvious symptoms.

When blood pressure stays high over time, it puts extra strain on your heart and blood vessels. This can damage the artery walls, making it easier for cholesterol and other fatty deposits to build up and narrow the arteries.

As blood flow becomes restricted, the risk of serious health problems such as heart attack, stroke, and kidney disease increases.

Caffeine stimulates the nervous system. This is the same system that kicks in when you’re stressed or alert. This can cause your heart to beat slightly faster, leading to tightening of your blood vessels and a temporary increase in blood pressure.¹

This may feel like you have increased energy. However, because caffeine is well-absorbed by the body, these effects are usually short-lived. Most people will experience some of these effects within 30 minutes of having coffee, but it depends on how sensitive you are to caffeine. For some people, the effects can last between 3 and 12 hours. If you’re not used to drinking a lot of coffee, the effects may feel stronger and last longer.

Australian guidelines recommend that healthy adults consume no more than 400mg of caffeine per day. This is about 2.5 cups of ground coffee or 5 cups of instant coffee.²

However, certain groups of people should be more mindful about drinking coffee. These include:

• Those who have already been diagnosed with high blood pressure.
• Caffeine-sensitive people who get headaches or palpitations after drinking coffee.
• Pregnant people. The current recommendation during pregnancy is 200mg of caffeine a day. Caffeine can increase the risk of miscarriage, difficult birth or a baby with low birth weight.³

Always get advice from your doctor about your blood pressure and the best way to manage it.

If you’re keen to reduce your caffeine intake, try:

• Drinking decaf in the afternoon. Most people can’t tell the difference after the first few sips. It’s an easy swap that protects sleep and blood pressure.
• Spread out your caffeine intake throughout the day and hydrate alongside water. Coffee is a mild diuretic, so pairing it with water helps reduce dehydration and lower blood pressure.
• Watch the size, not just the number. A large takeaway coffee can have multiple shots of coffee and equal 2 cups at home.
• Watch your soft drink and energy drink intake. A can of soft drink contains around 40mg of caffeine, and an energy drink can contain 80mg or more.

Your GP should check your blood pressure regularly. You can also get free blood pressure checks at your local pharmacy.

For the general population, a blood pressure below 120/80 mmHg is the ideal target and puts you in the best position for your heart and arteries.⁴

Speak to your doctor if you’re experiencing heart palpitations or dizziness, or if you have persistently high blood pressure readings.

The Heart Foundation offers information about blood pressure and how to manage it.

Health Direct provides the latest information and online resources on healthy blood pressure.