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Quick answer
Lemon water is simply water with lemon juice. Its main benefit is that it makes water more appealing, which helps some people drink more. It provides a little vitamin C, and the citrate in lemon juice may help some people prone to certain kidney stones.
The popular claims that lemon water detoxifies the body, burns fat, boosts metabolism or alkalises the body are not supported by evidence. And because lemon juice is very acidic, drinking it regularly, especially by sipping slowly through the morning, can erode tooth enamel. This is the risk most articles leave out.
The claims, checked
"It detoxifies your body"
Your liver and kidneys remove waste products continuously. There is no evidence that lemon water helps them work better. Drinking enough water does support the kidneys, but plain water does that just as well.
"It helps you lose weight"
There is no good evidence that lemon water burns fat or meaningfully boosts metabolism. Drinking water before meals may help some people eat slightly less, and replacing sugary drinks with lemon water cuts calories. Those are real benefits, but they come from the water and the drinks you are not having, not the lemon.
"It alkalises your body"
Lemon juice is acidic. Some argue it has an "alkalising effect" after digestion. Whatever happens in your urine, your blood pH is kept within a very narrow range by your lungs and kidneys, and food does not change it in healthy people.
"It boosts immunity"
The juice of half a lemon contains about 10 to 15 mg of vitamin C, a modest amount compared with the daily need of around 75 to 90 mg for adults. It contributes, but it won't protect you from colds on its own.
What might genuinely help
- Hydration: if lemon makes you drink more water, that is good, especially in hot climates.
- Kidney stones: citrate in lemon juice can help prevent calcium kidney stones in some people by binding calcium in the urine. Some kidney specialists suggest lemon juice in water as part of prevention, though medicines (potassium citrate) have stronger evidence. Discuss this with your doctor if you have had kidney stones.
- Less sugar: using lemon to flavour water instead of drinking juice or soft drinks.
How lemon water affects your teeth
Lemon juice has a pH of around 2 to 3, similar to many soft drinks. Acid softens the outer surface of tooth enamel, and repeated exposure gradually wears it away. This is called dental erosion, and lost enamel does not grow back. Signs include:
- Sensitivity to hot, cold or sweet foods
- Teeth looking more yellow (as the darker layer underneath shows through)
- Edges of the front teeth looking thin or translucent
- Fillings that seem to stand out
The biggest risk comes from sipping slowly over a long time, such as nursing a bottle of lemon water through the morning, because your teeth are exposed to acid repeatedly.
How to drink lemon water more safely
- Dilute it well. Use the juice of a quarter to half a lemon in a large glass (250 to 300 ml) of water.
- Drink it in one go or with a meal, rather than sipping for hours.
- Use a straw to reduce contact with your teeth.
- Rinse your mouth with plain water afterwards.
- Don't brush straight away. Brushing softened enamel can wear it further. Wait at least 30 to 60 minutes.
- Use fluoride toothpaste twice a day, which helps strengthen enamel.
- Avoid sucking lemon slices or eating lemons whole.
- Avoid drinking it right before bed, when saliva flow drops and acid stays in contact with teeth for longer.
Other side effects
- Heartburn: acidic drinks can trigger reflux symptoms in some people.
- Mouth ulcers: citrus can sting existing ulcers.
- Skin reactions: lemon juice on the skin followed by sun exposure can cause a burn-like reaction called phytophotodermatitis. Wash your hands after squeezing lemons outdoors.
Who should be careful
- People with sensitive teeth, enamel erosion or many fillings
- People with acid reflux or stomach ulcers
- People with mouth ulcers
- Children, whose enamel is thinner, should have lemon drinks only occasionally and with meals
When to see a doctor or dentist
- See your dentist if you notice tooth sensitivity, changes in colour or shape, or rough or thin edges on your teeth.
- See a doctor if you have persistent heartburn, difficulty swallowing, or signs of a kidney stone: severe pain in the side or back that comes in waves, blood in the urine, fever or vomiting.
- If you feel constantly thirsty despite drinking plenty, or pass large amounts of urine, see a doctor to check for diabetes.
Frequently asked questions
Is warm or cold lemon water better?
There is no evidence that the temperature changes any health effect. Choose whichever you prefer.
Can lemon water replace my morning coffee?
It won't give you caffeine, but some people find it a refreshing start to the day. If you drink both, have them with breakfast rather than sipping over hours to protect your teeth.
Is bottled lemon juice as good as fresh?
It works the same way for flavour and citrate, though it may contain preservatives and slightly less vitamin C.
How much water should I drink?
Needs vary with climate, activity and health. In hot weather, drink enough that your urine is pale yellow. People with heart or kidney conditions should follow their doctor's advice on fluid.
References
- Zero DT, Lussi A. Erosion: chemical and biological factors of importance to the dental practitioner. International Dental Journal, 2005.
- Penniston KL, et al. Quantitative assessment of citric acid in lemon juice, lime juice, and commercially-available fruit juice products. Journal of Endourology, 2008.
- NIH Office of Dietary Supplements. Vitamin C: fact sheet for health professionals. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
- NHS. Kidney stones: prevention. https://www.nhs.uk/conditions/kidney-stones/