How do I get the ammonia smell out of cloth nappies after washing?

What does an ammonia smell after washing actually mean?

If nappies come off a finished cycle smelling like a hamster cage, a stale toilet or hair dye, parents usually call that ammonia. Wee contains urea. When urea stays in bamboo, hemp or cotton, bacteria that ride in on wee and poo turn it into ammonia. The nappy can look clean and still hold that residue.

The NHS nappy-changing page does not give a home chemistry test. It does say cloth nappies can be machine-washed at 60°C, that they do not have to be soaked first, and that fabric conditioner should be left out because it makes them less absorbent and can add to nappy rash. That temperature-and-no-softener pair is the official UK starting point.

A dry nappy that only smells when you add a splash of water is still holding wee products. Smell after the wash is a wash-gap clue, not proof the brand is faulty.

How do I tell ammonia from farmyard, musty or leftover detergent?

UK Facebook groups mash several smells into one 'strip wash' post. Sorting the smell first stops you from treating musty-from-damp storage as if it were under-washed wee.

A nappy that only smells the moment baby wees, after coming off the line 'clean', is the sister symptom: leftover urea waking up when it gets wet again. That has its own page: why cloth nappies smell as soon as baby wees.

How do I run a detergent strip without vinegar or bleach?

The Nappy Alliance (the UK reusable-nappy trade body used by councils) describes a one-off deeper wash when nappies smell despite a normal cycle, or when a second-hand stash arrives. They call it a strip. The method is detergent and water, then rinse until the bubbles are gone.

1. 1
   Check the care label Which? says following the maker's temperature and detergent notes comes first — a 90°C idea can damage PUL, and mixed brands in one drum may need the gentlest label in the pile.
2. 2
   Wet the nappies in clean water Alliance wording: a rinse or cool quick wash with no spin and no detergent, so the next wash is not fighting a dry, packed drum.
3. 3
   Long 60°C wash, full detergent dose Use a full-length cotton-style cycle and a full dose of ordinary washing powder (the pack's heavily soiled / hard-water amount, matched to drum size). The UK Nappy Network uses the same 60°C full-dose idea, then rinse until all bubbles have gone.
4. 4
   Wash again with no detergent if bubbles remain Alliance: a further 60°C or 40°C wash with no detergent, and extra rinses while you can still see suds. Leftover foam is leftover product, and that can smell too.
5. 5
   Skip the internet additives Alliance: do not use chlorine bleach, vinegar, washing-up liquid or any cleanser not made for clothes. Which? separately says bleach and harsh stain removers can damage fabric and elastic and may void a warranty. Sunshine on the line is their stain route, not a bottle.

UK nappy shops warn that washing-up liquid, dishwasher tablets, vinegar soaks and household bleach are the Facebook recipes that void warranties. This page does not publish those recipes. A detergent strip is the published UK-body method.

What everyday wash stops the ammonia coming back?

A strip only clears what is already in the fibre. The smell returns if the next week of washes is still a short eco cycle with a splash of liquid and a stuffed drum. Which? sets a simple UK consumer routine: dry-pail (no soak), do not leave dirty nappies more than two to three days, warm pre-rinse, then a long hot wash, preferably 60°C.

• Fill, do not cram. North London Waste Authority says fill the machine to about three-quarters, run a quick cold rinse with no detergent, then a long Cottons-style wash at 40°C, or 60°C for babies under three months.
• Time and water. The UK Nappy Network asks for a cotton cycle of at least two and a half hours, extra water where the machine has it, and not the eco / quick setting.
• Detergent you can see working. Network guidance is a full dose of preferably non-bio powder, then adjust until you see suds in the main wash and none in the final rinse. NHS wording on skin is different: there is no evidence enzyme (bio) powders irritate a baby's skin. If you have bamboo, read the maker's label — some UK libraries avoid bio because of fibre wear, not because the NHS bans it.
• No fabric conditioner. NHS, Which? and NLWA all say the same: conditioner coats fibres and cuts absorbency.
• Poo off first; wash often. Which? says flush solids, dry-pail, and wash at least every two days so soiling does not sit. NHS says wash nappies dirty with poo separately from the rest of the laundry.

If the everyday wash is already a long 60°C with a sensible dose and the smell is still there, clean the machine drawer and door seal (Which? lists a dirty seal as a source of laundry smells) and run the strip once more in a drum that does not already smell.

If the nappies smell, should I treat this as nappy rash?

Ammonia in fabric and a sore bottom can show up together, but this page is not a diagnosis. The NHS nappy rash page lists wee and poo left on the skin, infrequent changes, detergent allergy, fragranced wipes and thrush among the usual causes. Their home steps are frequent changes, clean dry skin, nappy-off time, and no soaps, talc or tight nappies.

Which? also notes that some barrier creams coat cloth fibres. A liner keeps cream off the insert while you follow the NHS skin steps. If a rash is broken, spreading or not settling, that is a clinical question for your GP or health visitor — not a reason to add bleach to the drum.

In shortIn short: treat a hamster-cage smell after the wash as wee left in the fibre. Strip once with a full-dose 60°C detergent wash and extra rinses. Keep the weekly wash long, not eco, at the NHS 60°C where the label allows, and leave conditioner out. Vinegar and household bleach are not the UK-body method.