Quick answer

Let boiled water stand ten minutes (bath temperature for a child), fill to two-thirds and use a cover. Never sit, lie or lean on it, limit any one area to 20 minutes, then a few hours off, and take it out of bed before lights out. Never use one for babies, near numb skin or on a net-like mark. Cool a burn under running water for 20 minutes; call 999 if it is very large, deep or on the face, genitals or bottom, otherwise 111 if it blisters.

Table of contents

Three checks that settle every decision

The bottle: date wheel, rubber and stopper

Look for a small flower-shaped mark near the neck. CAPT, the Child Accident Prevention Trust, says: "The number in the middle is the year it was made, the flower segments represent the 12 months of the year and the dots inside those represent the number of weeks." MoneySavingExpert describes more than one way the dots are used and has seen "a few bottles with multiple dots in seemingly random places", so trust the year more than the month.

It shows when the bottle was made, not when it expires: RoSPA says the mark "indicates the month and year of manufacture", and NHS England South West says "Hot water bottle standards do not dictate an expiry date". On age, NHS National Services Scotland's burns network and the Children's Burns Trust say no more than two years by the date mark, NHS England South West says burns specialists recommend replacement every two years "from the time they are first used", and Heart of the South West Trading Standards says "two to three years after first use".

Our rule is the strictest you can check by looking: if this year minus the year in the middle is two or more, replace the bottle. If you cannot find or read the mark, replace it too.

A Swansea burns patient's bottle perished at "only around six months old", so check the rubber every time. RoSPA says: "Before each use, inspect your hot water bottle or warmer for cracks, splits or signs of wear. If in doubt, replace it." Each autumn, repeat CAPT's new-bottle test: fill it with cold water, put the stopper in, turn it upside down and squeeze gently to check for leaks.

The skin: a burn or a net-like mark

After each use, look at the skin that was under the bottle, in good light. For the lower back or the backs of the legs, use a mirror or phone photo, or ask someone. NHS Inform's back problems page says: "You should stop treating the area with ice or heat and seek advice from a medical professional if you notice an increase in redness, discolouration or blistering of the skin."

NHS Inform says burn symptoms may include red, peeling or swollen skin, pain, blisters, and white or charred skin, but do not wait for pain. A nurse quoted by Swansea Bay University Health Board slept with a bottle filled from boiling water, in a fur cover, woke with a large blister, "wasn't in pain", and needed a skin graft.

The Primary Care Dermatology Society describes toasted skin (erythema ab igne, or EAI) as net-like redness that at first fades when pressed and, with repeated heat, stays and darkens, often in the shape of the heat source. It comes from "a level of heat insufficient to cause a direct burn", so a bottle that never felt too hot can cause it.

None of the clinical descriptions we used covers brown or black skin, where early redness can be harder to see, so look for a lacy, net-shaped patch darker or lighter than the skin around it, and for swelling, peeling or blisters. Any net-like mark means stop using heat on that area (more below).

The person: can they feel the heat and move away?

Doctors at a UK burns unit wrote that in most contact burns the person has lost consciousness, most commonly by falling asleep, or has reduced feeling where the bottle lies. An Australian burns audit adds alcohol and "heavy sedated sleep", so after drinking, or after taking anything whose leaflet warns it can make you drowsy, our advice is not to fill a bottle or take one to bed.

NHS National Services Scotland's burns network says people with diabetes "may have altered or reduced sensation in their feet", and that people with spina bifida or cerebral palsy should be careful too. Diabetes UK, writing for people with neuropathy in their feet, says to fill with "hot water not boiling water", use a cover and "Always remove the hot water bottle from your bed before getting in"; South Tees Hospitals says "Do not use hot water bottles or toast your feet next to the fire or radiators." Diabetes Scotland's advice, quoted by NHS National Services Scotland's burns network, includes "remove the bottle from your bed before getting in, and don't rest your feet on them at any time".

We side with the stricter line, as our winter boots guide does: no hot water bottle near feet that have lost feeling, and if you have diabetes, none in bed with you and none on your feet at all. We apply the same rule to any part of the body with reduced feeling, and to anyone who cannot move a bottle off themselves. NHS Inform's back problems page goes further: "If you have any issues with circulation or sensation, you shouldn't use ice or heat as a treatment for back pain."

Burns units in England and Wales treated 968 hot water bottle cases in 2024, up from 501 in 2020, BSI reported in 2025. Children and adults over 65 saw the largest rises in hot water bottle burns between winter 2021 and winter 2022, a 2024 study in the journal Burns found. If you fill a bottle for a child or an older relative, these checks are yours to do.

Prep & Flow cycle-syncing meal prep cookbook Featured

15% OFF*Limited offer

One Sunday. A week of food, sorted.

23 high-protein recipes, cycle-synced for women who lift.

23 recipes · 60-page PDF · Instant download

£19.20 £16.32

See it on Etsy

*Seller's discount on Etsy - may end at any time.

Month by month, September to April

Treat the months below as prompts, not dates: a cold snap in September starts everything early.

September and October: out of the cupboard

CAPT says the rubber "can degrade if you freeze them", so a bottle frozen over the summer should not be used again in the colder months. Buying new, CAPT says to "Check for the British Standard mark starting with BS, look for a manufacturer's mark and check the daisy symbol."

November: the nightly habit

A bottle used most evenings for period or back pain sits on the same patch of skin. Keep to the 20-minute limit and break below, and check the skin after each use.

December: coming in from the cold

Do not press a hot bottle onto chilled hands or feet. The Royal College of Podiatry says rapid warming is thought to be one cause of chilblains: "if the skin is chilled and is then followed by too rapid warming next to a fire or through using a hot water bottle, chilblains may result." Our Christmas market guide covers warming up slowly.

January to April: the long run and storage

Toasted skin typically develops "over weeks to years" of repeated heat, says StatPearls, a US clinical reference, so an autumn habit may show now: the toasted skin section explains what to expect. When the cold nights end, empty and store the bottle as in the last filling step.

Filling and using it, in order

Check the bottle before you boil the kettle

Look at the date wheel, check the rubber and seams for splits or cracks, and make sure the stopper screws in straight and tight.

Boil the kettle, then let it stand

Never pour boiling water in, including from a boiling-water tap. NHS National Services Scotland's burns network says to let it cool for "a few minutes", the Children's Burns Trust "about 5 mins" and NHS England South West "at least 10 minutes"; we would wait the full ten. For a child, CAPT says to use "cooled boiled water that is around bath temperature", and kettle water stays far hotter than that for a long time, so mix in cold water rather than waiting longer: Heart of the South West Trading Standards says you can "add a mix of cold and hot water to the bottle". Check it feels no warmer than a bath before it goes near a child.

Hold it upright and fill it to two-thirds

The Children's Burns Trust says bottles "should only be filled by adults" and "held upright by the neck". Pour slowly, because Swansea's burns centre sees people who "miss the bottle and pour the hot water over their hand", and stop at two-thirds.

Let the air out and close it

Squeeze the air out gently, "holding the neck away from you as you do it", in the Children's Burns Trust's words, then screw the stopper in straight and tight and check the neck for drips.

Put it in a cover

NHS National Services Scotland's burns network says "Always use a cover to protect skin", and RoSPA says to use a fabric cover or wrap the bottle in a towel. A cover is not a guarantee: a Swansea plastic surgeon reports injuries "from prolonged contact with the bottle or part of the bottle cover whilst patients are asleep".

Never sit, lie or lean on it

That includes leaning back on one wedged behind you: RoSPA says "Pressure can cause the bottle to burst or leak." For period pain, the NHS suggests one "wrapped in a tea towel on your tummy". Rest it on top of you, on your tummy while you lie on your back or on your lower back while you lie on your front, never pinned under you or hugged tight. Swansea Bay University Health Board says "DO NOT allow direct contact with one area of the body for more than 20 minutes", and NHS Inform's shoulder problems page says to apply heat or ice "for no longer than 20 minutes at a time and leave a few hours between treatments". We would keep to both limits for any use, even with a cover: lift it off rather than sliding it along, and set a phone timer when it goes on.

Take it out before lights out

Warm the bed, then take the bottle out of bed before you turn the light off: a sleeping person cannot move away from the heat. If you might nod off on the sofa or in a chair, take it off first. Never leave a child to fall asleep with one. After drinking, or after taking anything whose leaflet warns it can make you drowsy (if unsure, ask a pharmacist), do not fill a bottle or take one to bed, and nor should anyone who cannot move it off themselves; keep it away from any part of the body with reduced feeling. Never put one in a bed a baby may sleep in, even to warm it first (see the FAQ below).

Empty it and store it dry

Once the water has cooled, empty it: Swansea Bay University Health Board says a bottle not in use "should be completely drained of water and the stopper removed" and stored "away from direct sources of heat or sunlight", which rules out the airing cupboard CAPT warns against.

When it goes wrong: scalds, burns and toasted skin

A scald or burn: NHS first aid

The NHS page for England covers burns and scalds, in full:

You should treat all burns and scalds straight away.

  • Hold the burn or scald under cool running water for 20 minutes. Do this as soon as possible, within 3 hours of it happening. If there's no running water available, you can use cool bottled water or a wet towel.
  • Remove any clothing or jewellery that's near the affected area - but do not remove anything that is stuck to the affected area.
  • When the burn or scald has cooled, lay cling film over it if you can. Do not wrap the cling film around it.

Immediate action required: Call 999 or go to A&E if:

You have a burn or scald that:

  • is very large or deep
  • is on your face, genitals or bottom
  • has been caused by an acid or chemical, or by electricity

Do not drive to A&E. Ask someone to drive you or call 999 and ask for an ambulance. Bring any medicines you take with you.

Urgent advice: Get help from NHS 111 if:

  • you or your child has a burn or scald and you're not sure what to do

You can call 111 or get help from 111 online. Call 111 if you need advice for a child under 5 years old.

If a bottle bursts over your thighs or tummy, a shower counts: the British Burn Association says to "cool the burn under running water or a shower for at least 20 minutes". NHS Inform, for Scotland, adds: "Keep yourself or the injured person warm. You can use a blanket or layers of clothing to do this. But, avoid putting these on the injured area."

The British Burn Association's advice, published by NHS England South West, says "Call or visit NHS 111 for any burn larger than a 50p piece or if there are any blisters", and the same page adds: "If the wound is not healed within two weeks, or there are signs of infection, seek further advice from your GP, NHS 111, a local Minor Injury Unit or Emergency department."

A burn from a bottle can be serious without hurting: the nurse above "wasn't in pain" and needed a skin graft, and NHS Inform lists "white or charred skin" among burn symptoms. Feet are among the commonest sites a UK burns unit recorded, and people with diabetes may not feel a burn happening. So our advice goes further than the NHS page: with a blister, white or charred skin, a burn on a hand or foot, or any burn in someone with diabetes or reduced feeling in that area, do not wait and see. Call 111 and say so, or if anything on the NHS 999 list above applies, call 999 or go to A&E and do not drive yourself.

While it heals, the NHS page for England says:

Do

  • take painkillers such as paracetamol or ibuprofen to help with pain
  • use an emollient ointment on the affected area if it becomes itchy and dry as it heals - you can ask a pharmacist for advice about what to use

Don't

  • do not put any creams, oils or butter on burns or scalds
  • do not use plasters or sticky dressings to cover a burn or scald
  • do not burst any blisters

NHS Inform also says "Cool the burn with cold running water for 20 minutes" and "Never use ice, iced water, creams or greasy substances like butter on a burn", and that while the skin heals, "don't apply any creams or greasy substances". So put no creams, oils or butter on a fresh burn, and ask a pharmacist before putting anything on a healing one.

A net-like mark: toasted skin

A net-like mark on its own is not an emergency: stop using heat on that area and get advice from a medical professional. The Primary Care Dermatology Society (PCDS), which writes for GPs, says: "If the skin changes are only mild they are likely to resolve over several months. If the skin changes are more severe they are likely to persist".

A mark is not a cancer diagnosis, but PCDS says there "appears to be a small long-term risk of squamous cell carcinoma or Merkel cell carcinoma developing in areas of EAI - the latent period may be 30 years or more" and tells GPs to refer "enlarging skin lesions or persisting areas of ulceration" in the mark urgently. See your GP, and mention the heat, if a sore in the mark will not heal or a lump or patch in it is growing, even years later.

Do not buy anything for the marks: treatments for them appear only in case reports and medical reviews. Ask your GP about the pain behind the heat instead, since the NHS lists back pain that "does not improve after treating it at home for a few weeks" and period pain "stopping you doing your usual daily activities" among its reasons to see one.

Frequently asked questions

How long do hot water bottle marks last?

First, stop using heat on the marked area and get advice from a medical professional. Marks on skin from repeated heat are likely to resolve over several months if mild and likely to persist if more severe, says the Primary Care Dermatology Society, and the NHS says a small burn or scald can take around two weeks to heal, though we would call 111 for any blister. If you mean the flower-shaped date mark, it shows when the bottle was made, not when it expires, and UK safety advice mostly says to replace a bottle at about two years, counted from different starting points.

Is it safe to fall asleep with a hot water bottle?

UK sources disagree. Age UK suggests bottles "under blankets or duvets to keep you warm while you're sleeping", but Swansea Bay University Health Board's 2019 advice was "Avoid taking the bottle to bed". Doctors at a UK burns unit wrote that in most contact burns the person has lost consciousness, most commonly by falling asleep, or has reduced feeling where the bottle lies, so our rule is to warm the bed, then take the bottle out of bed before you turn the light off.

Can a baby or child have a hot water bottle?

Not a baby. The NHS says "Babies should never sleep with a hot water bottle or electric blanket, next to a radiator, heater or fire, or in direct sunlight", and The Lullaby Trust says not to use them "in any baby sleep space (cot, crib, Moses basket or adult bed)", and in a 2023 post on X said not to use them "to heat a baby's sleep space (even if you remove it before they get in)". For children, the Children's Burns Trust urged families in 2024 "to avoid using hot water bottles for children"; if you do use one, CAPT says to use "cooled boiled water that is around bath temperature", a cover, and no sitting or lying on it.

Can I use a hot water bottle with an electric blanket?

No. Age UK says "Make sure to never use a hot water bottle with an electric blanket", Electrical Safety First says "Water and electricity don't mix", and nidirect advises against it "to prevent the risk of electrocution".

Is a wheat bag or electric heat pad safer for skin?

Not automatically. DermNet lists "Repeated application of hot water bottles or heat pads to treat chronic pain" among the heat sources behind toasted skin, and Dorset & Wiltshire Fire and Rescue Service says "Don't use wheat bags as bed warmers" because "they can continue to heat up and can set bedding alight".