The Downsides Of Caffeine Intake

The average American adult consumes about 300 mg of caffeine per day.[1] That’s equivalent to the caffeine content of nearly three cups of coffee (we have previously covered how much caffeine is safe to consume.

With so much caffeine being consumed by so many people, it’s worth taking a look at potential downsides. We recently added some side effect data to our caffeine page, and here’s a quick summary of what we found:

Blood pressure

It’s pretty clear that caffeine increases blood pressure in the short term, and this spike seems to be stronger in people prone to hypertension. This acute response is also much more pronounced in people who don’t normally ingest caffeine. But these acute effects wear off after around 4 hours.

What’s less clear is caffeine’s long-term effects on blood pressure.[2] The overall long-term effects are inconclusive,[3] with the big picture being obscured in part to different responses seen with pure caffeine ingestion and studies involving caffeinated beverages such as coffee. One meta-analysis of studies with a median length of 42 days found that pure caffeine bumps up blood pressure by about 4/2 mmHg, whereas coffee intake bumped systolic blood pressure by about 1 mmHg with no significant effect on the diastolic number.[4]