The sale of energy drinks could be banned in England to anybody under 18, amid fears they are damaging children's health, the prime minister has said.
The government has launched a public consultation on its plans to make it illegal to sell the drinks to children.
Energy drinks contain high levels of sugar and caffeine and have been linked to obesity and other health issues.
The government is asking for views on what age the ban should apply to, but gave under 16 and under 18 as options.
Scotland, Northern Ireland and Wales have the power to implement their own bans.
UK youngsters are among the highest consumers of energy drinks in Europe, research has previously suggested.
The drinks contain high levels of caffeine and sugar, often much more than those of standard soft drinks.
Excessive consumption has been linked to a range of health issues in children, from obesity, tooth decay, headaches and sleep problems to stomach aches and hyperactivity.
Surveys from teachers unions have also suggested that they contribute to poor behaviour in classrooms, although claims they can alter behaviour have been contested.
The ban would apply to drinks containing 150mg of caffeine or more per litre.
Many shops already have their own voluntary bans in place for under-16s, but it is still possible for children to buy the drinks from some retailers and vending machines.
Public Health Minister Steve Brine said: "We all have a responsibility to protect children from products that are damaging to their health and education, and we know that drinks packed to the brim with caffeine, and often sugar, are becoming a common fixture of their diet.
"Our children already consume 50% more of these drinks than our European counterparts, and teachers have made worrying links between energy drinks and poor behaviour in the classroom."
Reality Check: Is caffeine bad for your health?
The two main ingredients of concern in energy drinks are sugar and caffeine.
We know having a diet too high in sugar risks weight-gain, which is in turn is linked to heart disease, some cancers and type 2 diabetes. But how much do we know about what caffeine does to young people's bodies in the short and longer-term?
In the short-term it can cause headaches on withdrawal, irritability, raised blood pressure and heart-rate.
But there isn't much good evidence that caffeine directly harms health, including that of children, in the longer term.
Although it raises blood pressure in the short-term, there is no association with hypertension (chronic high blood pressure).
However, the shorter-term symptoms caffeine causes may indirectly lead to other health issues.
For example, there's plenty of evidence linking disturbed sleep to a range of negative health consequences, including weight gain.
One study linked energy drinks to "poor quality or reduced sleep, headaches, risk-seeking behaviour and depressive symptoms".
The maximum recommended intake of caffeine for children is lower than for adults - no more than a daily serving of 2.5mg for every kg a child weighs - meaning it's easy for a young person to over-consume caffeine if they drink energy drinks.
Food labelling laws already state that any soft drink with more than 150mg of caffeine per litre must carry a warning about its high caffeine content and are not recommended for children or pregnant or breastfeeding women.
Prime Minister Theresa May said: "Childhood obesity is one of the greatest health challenges this country faces, and that's why we are taking significant action to reduce the amounts of sugar consumed by young people and to help families make healthier choices.
"With thousands of young people regularly consuming energy drinks, often because they are sold at cheaper prices than soft drinks, we will consult on banning the sale of energy drinks to children.
"It is vital that we do all we can to make sure children have the best start in life and I encourage everyone to put forward their views."
What is in energy drinks?
Energy drinks contain high levels of caffeine, usually about 80mg in a 250ml can.
In comparison, a 330ml can of classic Coca-Cola contains 32mg and a can of Diet Coke 42mg.
Energy drinks also contain lots of sugar as well as other ingredients including vitamins and minerals or herbal substances.
Some smaller "energy shot" products can contain as much as 160mg of caffeine in a 60ml bottle.
How much caffeine is too much?
- High levels of caffeine can lead to anxiety, panic attacks and increased blood pressure
- Pregnant and breast-feeding women are advised not to have more than 200mg of caffeine over the course of a day
- European advice says that most other adults are safe to drink up to 400mg a day
Source: NHS Choices
What are the health harms of too much sugar?
Too much sugar in our diets is linked to a range of health problems including:
- Tooth decay
- Type 2 diabetes
Duncan Selbie, chief executive of Public Health England, said: "Children do not need energy drinks to get through the day - they offer nothing more than unnecessary sugar.
"Restricting the sale of these drinks is another bold step needed to turn the tide on childhood obesity."
Prof Russell Viner, president of the Royal College of Paediatrics and Child Health, said: "There is no evidence that energy drinks have any nutritional value or place in the diet of children and young people.
"It's therefore worrying that so many young people are buying these drinks at low prices and consuming them on a regular basis."
Energy Drinks Europe, which represents drinks manufacturers, said a 250ml can of energy drink typically contained about the same amount of caffeine as a cup of coffee and as much sugar as that in juices and soft drinks.
A spokesman added: "For all ages, there are much greater contributors of caffeine and sugar in the diet than energy drinks.
"A sales ban on energy drinks is therefore arbitrary, discriminatory and not effective.
"A better approach is to work with governments to ensure a fact-based discussion rather than proposals based on conjecture. Effective measures would include portion control and serving size reductions."
The public consultation follows the June 2018 publication of the latest chapter of the government's Childhood Obesity Plan, which commits to halve childhood obesity by 2030.
It will last for 12 weeks.