Is your teen getting too much caffeine - and how much is harmful?

Sep 3, 2025
3 min read

Updated: Jul 22

Caffeine is well known for increasing energy levels and it’s easily available, so many teens look to it for a boost when they’re flagging. It’s fast-acting, meaning most of us can feel the effects within half an hour, and for some in less than five minutes.

Caffeine affects us all in different ways. Initially the impact can be positive (feeling more awake and able to concentrate), but caffeine stays in the system for up to twelve hours and can have negative side-effects such as preventing sleep and causing restlessness and anxiety. Some people are more sensitive to it than others. On average, adults shouldn’t consume more than 400mg of caffeine a day, and adolescents should have much less. Like most things, in large doses caffeine can be harmful.

Different ways your teen can be getting too much caffeine

We all know there’s caffeine in coffee, but it’s also in tea, energy drinks and chocolate, so keep an eye on how much of these your child consumes. Energy shots and caffeine pouches are often very high in caffeine and a firm favourite with teens.

Drinks with high caffeine (more than 150mg per litre) have to show this on the label, although it isn't always clear, and it doesn’t apply to drinks bought in coffee shops. Lots of high-caffeine products are available in health food shops, which can give the impression they’re good for wellbeing, but that's not always the case if consumed in large quantities.

Energy shots and drinks

Energy shots are often very high in caffeine and a firm favourite with teens. They can be deceptive as they're tiny in quantity but packed with caffeine; for example, a 60ml shot can contain around 200mg. Likewise, many energy drinks don’t have a huge percentage of caffeine, but they're served in large volumes (half-litre bottles), so the amount your child is drinking is a lot (around 160mg in a can of Monster), whereas a small glass of the same product would be fine.

Most supermarkets and high street stores have banned sales of energy drinks to under-16s. This is currently voluntary, although the Government is planning to make it law in England.

Coffee

If your child regularly drinks one or two cups of coffee a day, it’s absolutely fine to continue, even during exam time, as their body will be used to it. What’s not good is introducing changes, so they shouldn’t start drinking coffee during revision periods to stay alert if it's not something they normally do. It’s more likely to make them jittery, hyper and unable to concentrate.

Food

Less obvious sources of caffeine are foods. Chocolate cake with chocolate frosting, or cupcakes with chocolate topping, are likely to be high in caffeine (as well as sugar), so they're not ideal as a dessert after dinner. Coffee-flavoured products can also contain lots of caffeine, so look out for ice creams, frozen yoghurts and milkshakes.

Isotonic gels

Teens often love isotonic gels, some of which contain as much as 75mg of caffeine per pack. These are fine in moderation, but watch out that your child isn’t having too many, or reaching for an energy rush when they're thirsty and should be drinking water.

Caffeine pouches

This trend is growing in America and, although not yet common in the UK, caffeine pouches are becoming more readily available here. Teens suck on small pouches, a bit like a teabag and about the size of a sugar stick, to get an instant caffeine hit into the bloodstream.

How much caffeine is harmful?

On average, adults shouldn’t consume more than 400mg of caffeine a day, and adolescents should have much less. Too much caffeine can result in loss of sleep, loss of energy, low mood and low concentration, the opposite of what’s needed to study and revise well.

Caffeine is also long-lasting, so drinking high-caffeine drinks in the afternoon can still affect your child’s ability to sleep that night. It’s an absolute no to drink coffee (or other caffeine-fuelled drinks) late in the evening to try to overcome tiredness and stay up later.

Managing your teen's caffeine intake

Keep an eye on their caffeine intake and, if possible, get them to avoid it completely from lunchtime as a year-round rule. When teens have caffeine-laden drinks first thing, it's often to boost energy because they haven't slept enough. Help your teen sleep better by creating a calming evening routine so they wind down before bed.