Understand Your Numbers

Does caffeine raise blood pressure? Coffee, tea and energy drinks, honestly

Caffeine does move the number. The useful questions are by how much, for how long, and whether it still matters if you drink it every day. The answer also changes one small thing about how you take your own readings.

NK Medically reviewed by Dr Nouman Kazmi, MBBS FCPS ·8 min read

Key Takeaways

Caffeine can temporarily increase blood pressure, the British Heart Foundation says, especially in people who don’t usually drink it.
Cleveland Clinic puts the rise within about 30 minutes of the drink, peaking after roughly an hour. A morning cup of coffee can move the reading by up to 10mmHg.
Habit changes it. In a 15-volunteer study described by Harvard Health, a triple espresso pushed systolic pressure up by 13mmHg in people who weren’t coffee drinkers, and didn’t move it at all in those who were.
A moderate amount every day isn’t linked to a raised risk of long-term high blood pressure, according to the BHF. Up to 400mg a day, around four to five cups of tea or coffee, is generally considered safe for most adults.
It matters most when you’re measuring. The BHF says to wait at least 30 to 60 minutes after any coffee or tea before having your blood pressure checked.

In This Article

The short answer, and the size of it
When it happens, and how long it lasts
The decaf result that complicates things
What happens if you drink it every day
How much caffeine is actually in your cup
What it means for your own readings
Frequently asked questions
The bottom line

The short answer, and the size of it

Yes. Caffeine raises blood pressure, briefly. Coffee gets a health headline about once a week, and has done for thirty years, in both directions. Which is a shame, because the short-term part of this is one of the few bits that’s genuinely settled.

The British Heart Foundation puts it plainly: caffeine can temporarily increase blood pressure, especially in people who do not usually drink it. Temporarily is doing a lot of work in that sentence, and we’ll come back to it.

The mechanism is physical. Cardiologist Dr Luke Laffin, writing for Cleveland Clinic, explains that caffeine narrows, or constricts, your blood vessels. Narrower vessels mean the heart has to work harder, and it takes more pressure to push blood around your body. The pipe gets a little tighter and the pump pushes a little harder. Nothing exotic is happening.

As for the size of it, Cleveland Clinic gives a figure worth remembering: a morning cup of coffee can raise your blood pressure by up to 10mmHg, and a second, third or fourth cup keeps those numbers climbing. In Dr Laffin’s words, caffeine can move your blood pressure from what’s considered “controlled” to “uncontrolled” pretty easily.

That is a real effect, and it’s also a temporary one. Those two facts sit together more comfortably than most coverage of coffee suggests.

mmHg is what Cleveland Clinic says a single morning coffee can add to a blood pressure reading. For comparison: the NHS calls it high from 140/90 at a surgery, and from 135/85 for a reading you take at home. Those two are 5mmHg apart.

When it happens, and how long it lasts

Cleveland Clinic sets out the shape of it. The increase in blood pressure typically takes place within 30 minutes of a caffeinated drink and peaks after about an hour. Then, as Dr Laffin says, it lingers for a bit before your blood pressure comes back down.

The caffeine itself hangs around rather longer than the pressure does. The BHF says your body absorbs caffeine in around 45 minutes, and that it has a half-life of about five hours, so a cup with 100mg in it at noon still leaves 50mg in your system by 5pm. Depending on your sex, whether you smoke and how your liver works, caffeine can stay in your system anywhere between two and ten hours.

So the window that matters for a reading is a narrow one, and it’s the hour after the cup rather than the whole day. An afternoon reading isn’t being distorted by the coffee you had at eight in the morning. The reading you take twenty minutes after that coffee is a different matter.

The decaf result that complicates things

Here’s where the neat version falls apart. It’s worth knowing about, because it explains why the research has been so inconsistent.

Harvard Health describes a study in which researchers from Switzerland and the United States monitored 15 volunteers. None had high blood pressure, none had hypertensive parents, all were healthy non-smokers, and only six were habitual coffee drinkers. Each person was measured under four conditions: a triple espresso, a decaffeinated triple espresso, 250mg of caffeine given by intravenous injection, and a saline placebo.

The triple espresso raised systolic pressure by an average of 13mmHg and diastolic pressure by 7mmHg in the volunteers who weren’t coffee drinkers. In the habitual coffee drinkers, it didn’t raise their pressure at all.

The straight caffeine injection should have been the stronger intervention, and on blood caffeine levels it matched the espresso. It moved systolic pressure by an average of just 6mmHg, and it moved it similarly in both groups.

Then the decaffeinated espresso, which raised blood caffeine levels not at all, pushed the non-drinkers’ systolic pressure up by 12mmHg. Almost as much as the real thing.

“Does caffeine raise blood pressure” and “does coffee raise blood pressure” aren’t quite the same question, then. A cup of coffee contains hundreds of compounds, and Harvard Health’s reading of this study is that the pressure-raising effects of coffee seem to depend on ingredients other than caffeine. Fifteen people is a small study, so hold it loosely. It does explain a lot of contradictory headlines.

What happens if you drink it every day

This is the question most people actually have, and the answer is more reassuring than the headlines.

The BHF says that having a moderate amount of caffeine every day is not linked to an increased risk of long-term high blood pressure. It goes further for people already diagnosed: if you have high blood pressure and already drink caffeine regularly, you will probably not need to cut your intake down, though the BHF asks you to check with your doctor rather than take that as settled for you personally.

Cleveland Clinic is a little more cautious on the same point. Its guidance is that most healthy adults can have up to 400mg of caffeine a day without adverse effects. If you have been diagnosed with high blood pressure, it recommends keeping below 400mg, and asking your healthcare provider what your own limit should be.

Dr Laffin adds one thing that’s easy to miss. Caffeine hits everyone differently, and not feeling the jolt doesn’t mean it isn’t doing anything. Caffeine does bump up blood pressure and heart rate whether or not you notice, and over time that extra load on your heart and vessels can add up.

The NHS keeps it to a single line on its high blood pressure pages: do not drink too much caffeine. The drinks it names as high in caffeine are coffee, tea and cola.

If your daily amount has been creeping up, the tiredness underneath it is worth a look. Dr Laffin’s suggestion is to check the obvious candidates: whether you’re sleeping enough, whether it’s stress, whether something medical is making you tired. Cutting down gets easier once you know which one it is.

How much caffeine is actually in your cup

400mg is around four to five cups of tea or coffee, according to the BHF, and the exact amount varies by brand and by how long the drink is brewed. These are the averages it publishes:

Filtered or instant coffee (200ml): 90mg
Espresso (60ml): 80mg
Standard energy drink (250ml): 80mg
Black tea (220ml): 50mg
Standard cola (355ml): 40mg
Green tea (220ml): 35mg
Dark chocolate (20g): 10mg
Decaffeinated coffee (200ml): 7mg

Two footnotes on that list. Caffeine supplements and powders often carry far more than any food or drink, so the BHF says to check the label before trying them. And in pregnancy, the BHF cites the NHS recommendation of 200mg a day or less, half the general figure.

A 250ml energy drink and a single espresso carry the same 80mg, which isn’t how either of them feels.

What it means for your own readings

If you take your blood pressure at home, this is the part that changes what you do.

The BHF’s instruction is specific: avoid having caffeine before you have your blood pressure checked, and wait at least 30 to 60 minutes if you’ve had any coffee or tea. That window lines up with Cleveland Clinic’s timing: the rise arrives within half an hour and peaks at about an hour.

The reason it matters is the thresholds you’re measuring against. The NHS considers blood pressure high at 140/90 or higher when a healthcare professional checks it, or 135/85 or higher when you check it at home. Those two figures are 5mmHg apart. A cup of coffee, on Cleveland Clinic’s numbers, can be worth twice that. A reading taken with a coffee still working through you isn’t wrong, exactly, but it isn’t measuring what you think it is.

If you’re over 80, the BHF puts the figures a little higher: your blood pressure should usually be below 150/90mmHg when a healthcare professional checks it, or below 145/85mmHg when you check it at home. Either way the same thing holds, and the BHF is clear that these are guidance ranges to discuss with your healthcare team rather than lines you cross or don’t.

So, in practice:

Take the reading before the first coffee of the day, or leave 30 to 60 minutes after it.
Same time, same arm, same chair, every time. We’ve set the method out in how to measure blood pressure correctly at home.
If you’ve had one anyway, write that down next to the number rather than skipping the reading. A noted reading beats a gap.
Keep going for six to eight weeks before you draw any conclusion from it.

That last one does most of the work. Blood pressure moves all day, for all sorts of ordinary reasons, and caffeine is only one of them. Why does blood pressure fluctuate covers the rest of the list. A single high reading after a strong coffee tells you about that coffee. Six weeks of readings taken the same way tells you about your blood pressure, and that’s the thing a GP can work with.

If a check has already suggested your blood pressure might be high, the NHS says you may be asked to use a monitor at home over the next few days, to come back for another check, or to wear a portable monitor that takes readings across 24 hours. Knowing to leave the coffee alone beforehand makes those few days worth more.

Matter BP Tracker

One coffee is noise. Six weeks is a trend.

The Matter BP Tracker holds the reading, the date and the note that goes with it. So the high morning after a strong coffee is still there in six weeks, labelled as what it was. What you hand your GP is a pattern rather than a memory. The next reading is tomorrow morning.

Open the BP Tracker → Readings and notes·Charted over weeks

Frequently asked questions

Does caffeine raise blood pressure?

Yes, temporarily. The British Heart Foundation says caffeine can temporarily increase blood pressure, especially in people who do not usually drink it. Cleveland Clinic puts the size of it at up to 10mmHg from a single morning cup of coffee, with the rise arriving within about 30 minutes and peaking after roughly an hour. The effect is short-lived, and it is smaller in people who drink caffeine regularly.

How long does caffeine affect blood pressure?

About an hour for the peak, then it fades. Cleveland Clinic describes the increase as taking place within 30 minutes of a caffeinated drink and peaking after about an hour, before lingering a little and coming back down. The caffeine itself outlasts the pressure effect: the BHF says caffeine has a half-life of around five hours, so a 100mg cup at noon leaves 50mg in your system by 5pm.

Should I avoid coffee before a blood pressure reading?

Yes. The BHF says to avoid caffeine before having your blood pressure checked, and to wait at least 30 to 60 minutes if you’ve had any coffee or tea. It matters because the thresholds are close together: the NHS considers blood pressure high at 140/90 or higher at a surgery, or 135/85 or higher when you check at home, and those two figures are only 5mmHg apart. If you’ve had a coffee anyway, take the reading and note it alongside the number.

Can I still drink coffee if I have high blood pressure?

Probably, but check with your own doctor. The BHF says that if you are diagnosed with high blood pressure and already regularly drink caffeine, you will probably not need to cut your intake down, while asking you to confirm that with your doctor. Cleveland Clinic recommends keeping below 400mg a day if you have been diagnosed, and suggests asking your healthcare provider what your own daily cap should be.

Does decaf coffee raise blood pressure?

It did in one study, which is why this is more complicated than it looks. Harvard Health describes research on 15 volunteers in which a decaffeinated triple espresso raised systolic pressure by an average of 12mmHg in people who were not habitual coffee drinkers, despite raising their blood caffeine levels not at all. A triple espresso with caffeine raised it by 13mmHg in the same group. Harvard’s reading is that the pressure-raising effects of coffee seem to depend on ingredients other than caffeine. It is a small study, so treat it as a reason to be curious rather than a settled finding.

How much caffeine is too much?

Up to 400mg a day, or around four to five cups of tea or coffee, is generally considered safe for most adults, according to the BHF. On its figures, a 200ml filtered or instant coffee carries about 90mg, an espresso about 80mg, a standard 250ml energy drink about 80mg and a cup of black tea about 50mg. The BHF notes that caffeine supplements and powders often contain much more than food or drink, so check the label, and that the NHS recommends 200mg a day or less in pregnancy.

The bottom line

Caffeine raises blood pressure for about an hour, by up to 10mmHg on a single cup, and considerably less than that if you drink it every day and your body has got used to it. A moderate daily habit isn’t linked to long-term high blood pressure, and the BHF’s view is that most people already diagnosed won’t need to give up their coffee, though that one is worth putting to your own doctor. What’s genuinely worth changing is the timing of your readings. Take them before the first coffee, or wait half an hour to an hour afterwards, keep the method the same, and judge the result over six to eight weeks rather than over one morning.

Continue Learning

References

British Heart Foundation. Is caffeine bad for you? How much is too much? Tracy Parker, Senior Dietitian. Page updated 9 June 2026. Available at: bhf.org.uk
NHS. High blood pressure (hypertension). Available at: nhs.uk
British Heart Foundation. High blood pressure (hypertension): causes and symptoms. Available at: bhf.org.uk
Cleveland Clinic Health Essentials. Is Caffeine Raising Your Blood Pressure? With Luke Laffin MD, 21 February 2025. Available at: health.clevelandclinic.org
Harvard Health Publishing. Coffee and your blood pressure. 19 January 2022. Available at: health.harvard.edu

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