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Frequently Asked Question

how does the warmer work?

The yoomi bottle contains a unique warmer that is activated by pressing the orange button. This triggers the internal solution to warm the unit in just 60 seconds.

The cold feed is gently warmed as it flows through the specially designed channels on the outside of the warmer. By the time the feed reaches the teat, it is at natural breast milk temperature (32-34 deg C). The warmer has been carefully designed to stay warm for up to one hour.

are the contents of the warmer safe?

Yes, the contents of the warmer are safe. The warmer contains the same gel as used in commonly available hand warmer packs.

The gel is a non-toxic, concentrated salt solution (It is used as an additive in ice cream). Just to be extra safe, we have added a food grade colourant so that any leaks are visible, and Bitrex®, a safe but bitter substance that will ensure that even if there is a leak, baby will not swallow any of the solution.


can yoomi overheat my baby's feed?

No, it cannot.

Our engineers have designed the yoomi system so that it is impossible for baby's feed to be warmed above a safe, maximum temperature (when used as instructed). This means that there is no possibility of baby being exposed to unsafe temperatures from either the bottle or the warmer.

how does yoomi help prevent colic?

The teat design features built-in anti-colic vents which ensure that air does not bubble through the teat and into the feed when baby drinks.

Make sure that you do not overtighten the collar to ensure that the anti-colic vents work properly.


how does yoomi help prevent colic?

  • do yoomi products contain BPA (Bisphenol-A)? No , they do not. All yoomi products are 100% BPA free.
  • how do I know when my warmer is ready to use (fully recharged)? Your warmer is ready to use when: 1) it has been allowed to cool after recharge (75 minutes at room temperature or 20 minutes in cold water), 2) it rattles when you gently shake it (when warmer is cool) and 3) the button is orange.
  • how do I know that the warmer has begun to warm up after I have pressed the orange button? After pressing the orange button firmly, please WAIT 30 seconds for the orange button to start fading. A blue button indicates that the warmer is warming up. Also, after 2-3 seconds the warmer will no longer rattle when gently shaken.
  • my warmer won’t activate - the rattle is there and sounds like a ball in liquid If your warmer has charged correctly and you have a rattle that sounds like a ball in liquid, yet your warmer will not activate, the activator inside the button has become dislodged. You can reset your warmer easily with the following steps;

    1. Put your warmer in the deep freeze (under the peas etc!) for 90 minutes but no longer.

    2. After 90 minutes, take the warmer out of the freezer and shake it. The rattle should still be there although it may sound a bit fainter - as if the contents inside have frozen.

    3. Press the button - it will be much harder to physically press than a warmer that has not been frozen - please don't be afraid and press hard. It may take a few repeated prods with slightly more force.

    4. It should activate as normal - you'll know if it has activated as the rattle will disappear within 2-3 seconds.

    5. Although you can't use this warmer for a feed, it will completely reset it and so you won't ever have to freeze it again.
  • the base of my warmer looks dented. Is this normal? Yes this is perfectly normal.

    When you first take the warmer out of its packaging, it needs to be charged before you can use it for the first time. The base of the warmer will looked 'dented' or 'sucked in'. This is normal. The material is flexible to allow the contents to change from liquid and vice versa. When the warmer is ready to use, it will be liquid inside and will rattle when gently shaken.
  • how do I know when I need to recharge the warmer? Your warmer needs to be recharged if there is no rattle when you shake it. This is because it is still solid inside after its last use. To recharge it you need to 'melt' the contents to take it back to a liquid so that it's ready to go again.

    A new warmer will always need charging before its first use.

    Coming Soon! The yoomi Pod will allow your existing warmers to be charged, fully protected, in the microwave in less than 2 minutes.

    Available Summer 2012!
  • when should I replace my warmer? Replace the warmer at the first sign of damage or if blue dye is visible.

    Replace your warmer after 100 uses.

    Replace your warmer if the button no longer turns orange at all after being cooled to room temperature.
  • how do I know I have used the warmer 100 times? There is a tick box table within the instructions to help you keep track of your usage. However a more visible sign is that the orange of the button fades with use and so when you are approaching 100 uses, the orange colour of the button will be very faded all of the time.
  • how can I sterilise and recharge the yoomi warmer? The warmer should be sterilised and recharged before each use. The best way to sterilise and recharge the warmer is to place in a pan of continuously boiling water for 25 minutes. Alternatively the warmer can be sterilised and recharged for 25 minutes in most electronic steam sterilisers. To do this add four times as much water as you would for a normal cycle i.e if you normally use 40 ml, use 160 ml instead.
  • my warmer has activated on its own, why has this happened? It may not have been charged for a sufficient period of time, try recharging it for 30 minutes to be sure. Very occasionally it is possible that the warmer can be activated by being bumped hard. Please handle the warmer with care.
  • does yoomi fit in conventional sterilisers from other manufacturers and which do you recommend to charge the yoomi warmers? All yoomi parts fit in conventional sterilisers from other manufacturers. It is best to sterilise the yoomi bottle separately from the yoomi warmer as the warmer requires additional time in the steriliser. The following electric steam sterilisers are compatible with yoomi warmers:

    Avent electronic steam steriliser: use 160ml of water to charge the warmer.
    Boots electronic steam steriliser: use 320 ml of water to charge the warmer.
    Mothercare electronic steam steriliser: use 280 ml of water to charge the warmer.
  • how soon after recharge can I use it again? Please be careful when handling the warmer as it will be very hot immediately after the completion of the sterilisation cycle or after having been in a pan of boiling water. Please let the warmer cool for 75 minutes (at room temperature) or for 20 minutes (in a bowl of cold water).

    If you use water, the warmer will no longer be sterile (fine for babies over 1 year) . Try using a cold water sterilisation solution to speed up the cooling and also keep it sterile for longer.
  • how long does the warmer stay charged? In general the warmer will remain recharged almost indefinitely and will be ready for use when you press the orange button - so it's up to you how often you would like to use your warmer. Very occasionally, it is possible that the warmer can be inadvertently activated if it is bumped hard, so keep it protected and remember that it will need re-sterilising if left for long periods.
  • my warmer does not recharge or will not stay recharged You may not be recharging the warmer for a sufficient length of time. Try recharging in a pan of boiling water for at least 30 minutes. Also make sure that you give the warmer at least 75 minutes to cool down after recharging (to be sure, wait until the button turns orange).
  • I have pressed the button when the warmer was hot, is this a problem? Yes, pressing the button when the warmer is hot deactivates the warmer and prevents the warmer from working. Unfortunately, the warmer will need to be replaced if this occurs.
  • my warmer is charged, but no longer sterile - how can I sterilise it? Do I have to recharge it again? Once your warmer is charged, it stays charged indefinitely, however it will need re-sterilising if you don't use it straight away. You can either put it on a regular sterilisation cycle (not in a microwave) but remember you'll have to let it cool. The perfect way to re-sterilise your warmers is to use a cold-water sterilisation solution such as Milton. This way you can sterilise the warmers and use them straight away.
  • Is there a possibility of reducing the recharge time? Yes. Our clever engineers have been working on reducing the recharge time. We're about to launch the 'yoomi pod' which allows you to charge your existing warmers in the microwave in less than 3 minutes. We're expecting to launch this in Summer 2012. Join the yoomi family to keep updated with the launch.....
  • does the warmer adversely affect the nutrients of my baby's feed? No, it does not. The yoomi warmer has been specially designed to gently warm baby's feed to breast milk temperature. This gentle process ensures that baby receives the maximum nutrition from the feed unlike other heating methods such as a microwave which can damage nutrients.
  • what is Bitrex®? Bitrex® is the brand name of a safe but bitter substance that has been added to the warmer to ensure that baby will not swallow any of the solution in the warmer. To learn more about Bitrex®, please visit
  • what are the benefits of using yoomi vs. using a conventional bottle? Whether you choose to bottle feed your baby or combine breast and bottle feeding, your yoomi has been carefully designed to create a more natural bottle feeding experience that's comforting for baby and convenient for you. A yoomi bottle can be used on its own or with a yoomi warmer. Combined with a warmer, yoomi warms feed to the natural temperature of breast milk in 60 seconds. Using the yoomi warmer means that your baby can be fed perfect 'breast-milk' temperature feed in just 60 seconds anywhere, anytime - you don't have to carry around any extra equipment and you don't have to rely on anyone else to help you warm your feed. It's the most practical solution to feeding on-the-go.
  • how does yoomi make combination breast and bottle feeding easier? Yoomi's soft, silicone teat has been carefully designed to more closely resemble the contours of mum's breast. Baby will be comforted by the ability to latch on easily, making it simpler to combine breast and bottle feeding.

    yoomi also facilitates combination feeding by gently warming baby's feed to breast milk temperature (32 to 34°C), which is a few degrees cooler than body temperature. Feed heated using other methods, such as hot water or the microwave, tends to be over-heated (typically 40°C) and can lead to baby preferring the hotter bottle feed to the cooler breast milk.

    Unlike conventional bottles where the warm feed will cool down, feed with yoomi will remain at a constant temperature making for a less interrupted and natural feeding experience.
  • can I use the yoomi bottle without the warmer? Yes, the yoomi bottle can be used without the warmer.
  • my bottle leaks - what can I do? The yoomi teats feature 6 air vents around the base which help reduce colic. Sometimes these vents can get squashed if the bottle is tightened too much, or if the teat is not aligned correctly, which can cause leaks. We suggest taking the bottle and collar, teats and warmer (if using) apart, and reassembling following our tips shown in our demonstration video.
  • the teat appears to collapse completely when my baby drinks from the bottle, is this normal? No, this is not normal. The collar has been over-tightened preventing the anti-colic vents from working. Unscrew the collar by a quarter turn to ensure the vents are working.
  • can I microwave my yoomi bottles, teats and warmers? yoomi bottles and teats can be placed in the microwave.

    yoomi warmers CANNOT be placed in the microwave.
  • why can I not place my warmer in the microwave? Because the warmer is a sealed unit containing liquid, the microwave can cause the warmer to burst, just like an egg. Our engineers have developed a way in which you can charge your existing warmers in the microwave using a protective pod. This unit will be available in Summer 2012.

    Please Join the yoomi Family to receive our newsletter with the latest developments.
  • can I place my yoomi bottles, teats and warmers in the dishwasher? Yes, all yoomi parts can be placed in the dishwasher.
  • can I place my yoomi bottles, teats and warmers in the fridge? Yes, all yoomi parts can be placed in the fridge.
  • how do I prepare infant formula feed? If preparing and storing infant formula feeds, please follow the latest FSA and DOH guidelines.

    Powdered infant formula is not a sterile product, so correct preparation and handling is needed to reduce the risk of illness.
  • what is the best way to transport feeds? If it is not possible to make a fresh feed while out and about, feeds should be cooled in a fridge (below 5°C) for at least 1 hour and transported in a cool bag. The yoomi bottle and warmer is fridge friendly.
  • I go to work and cannot make up infant formula fresh feeds for each feed. How can I prepare and store feeds in advance safely? If ready to use formula feed is not practical, the FSA suggest you prepare feeds in separate bottles and store in the back of the fridge at below 5°C. Feeds should never be stored for longer than 24 hours. The feed can then be warmed gently and safely using the yoomi bottle and warmer.
  • how does yoomi fit within the current guidelines? The yoomi bottle (on its own) can be used to make up fresh feeds, just like any other feeding bottle. Simply follow the Guidelines.
  • The yoomi bottle and warmer can be used for: warming up expressed breast milk that has been stored in the fridge.

    warming up ready to use carton formula feeds

    warming up feeds that have been prepared and stored safely in advance.
  • why do we think yoomi is the best warming system on the market? Lots of reasons!

    Safe & Hygienic - Conventional bottle warmers will warm the entire bottle of feed and so any bacteria in the feed will start to multiple immediately upon warming. If baby takes an hour to drink its feed, the bacteria has had an hour to multiply. The yoomi warmer only warms the feed the baby drinks, leaving very little time for the bacteria to multiply. If baby takes an hour to feed, the feed will remain cool until baby starts to drink, thereby minimising bacterial growth.

    Quick - Conventional bottle warmers will take approx 6 minutes to warm fridge temperature milk. Yoomi takes just 60 seconds, just what you need for those 3am night feeds.

    Perfectly safe temperature - Unlike other warmers, there is no second guessing whether the temperature is correct, yoomi warms to perfect breast milk temperature every time.

    Portable - no plugs, no batteries and no more carrying around flasks of boiling water, yoomi is the most practical solution to feeding on the go.

    The Safer Option - the guidelines strongly recommend against using the microwave to warm feeds due to the feed developing hot spots. Some parents are no longer using the microwave to warm baby's feed due to yoomi being just as quick but a safer option.
  • I'm struggling to find a teat that my baby will latch onto We understand that not all babies like all teats but we're confident that yoomi may be able to help. The soft, naturally shaped teat is popular with babies and our built-in warmer creates a naturally warm teat that makes yoomi a gentle way to introduce a first bottle to breastfed babies. Check out "the yoomi promise" ... if your baby doesn't like the yoomi teat and you cannot use your yoomi products, let us know within 14 days of receipt and we'll refund your order (UK only, other T's and C's apply - contact
  • where is yoomi made? yoomi is designed and assembled in London, England
  • what yoomi products are currently in your range? Our range currently includes:

    - the bottle (140ml or 240ml)
    - slow, medium and fast flow teats
    - the warmer
    - starter packs (exclusive to
    - multi-packs (exclusive to
    - gift sets (exclusive to
  • can I use the same warmer in the 5oz and 8oz bottle? Yes, the warmer is interchangeable across the range
  • where can I buy yoomi products? Yoomi is available both in the UK and internationally.

    See our yoomi retailers page for full listings in the UK and abroad, or buy online at
  • what is your returns policy? We have a standard returns policy of 28 days from delivery date - as long as the product is unopened and unused.

    Should there be a fault with the product, it must be reported within 3 months of purchase, we try to assess each issue individually and replacement products are issued at our discretion.

    Please note that we are unable to refund delivery charges where applicable.
  • the discount code I have doesn't work online Check the expiry date of the code, it may have been a limited offer. Also check where you are ordering from as yoomi HQ only offers codes valid on the UK shop site.
  • how long does delivery take? We dispatch our orders 3 times a week - Mondays, Wednesdays and Fridays. Orders will be dispatched as soon as we are able and are sent by Royal Mail Recorded Delivery. Foreign orders may take a little longer depending on the specific country.

    If your order has not arrived in the expected time, please contact the team on with your order number and country information in the subject line, we'll look into this and get back to you within 24 hours. Please give 28 days before you contact customer services.
  • can I travel on a plane with yoomi? Yes, yoomi is perfect for travelling, especially for long journeys where you may have difficulties warming your baby's milk.

    We recommend that you take as many warmers as possible to cover your feeding requirements whilst on a plane as you won't be able to recharge them until after your flight.

    The level of liquid inside the warmer is just under 100ml and so fine to travel with. It may be an idea to take a copy of the yoomi instructions with you in case any customs officers want further information. However many yoomi customers, and the yoomi team regularly fly with yoomi warmers.
  • can I recycle my yoomi products? yoomi uses polypropylene plastic, which is 'Grade 5' - BPA free and recyclable. The only part you cannot yet recycle is the warmer as the contents and the plastic need to be disposed of separately to make them recyclable. Our team are working towards implementing a recycling scheme - join the yoomi family to keep up to date with news.