Bio or non-bio detergent for cloth nappies in the UK?

What do the two UK schools actually disagree on?

The argument is not one hidden official rule. It is two published positions that talk past each other.

MayTally does not pick a winner. If the two sources clash, the manufacturer's care label is the one that can affect a warranty. The NHS line is the one that applies to skin irritation evidence, not to fabric wear.

What does the NHS say about bio detergent and a baby's skin?

On What you'll need for your baby the NHS writes that there is no evidence that washing powders with enzymes (bio powders) or fabric conditioners will irritate your baby's skin.

On How to change your baby's nappy the same enzyme line appears. That page adds a cloth-nappy rule that is about absorbency, not enzymes: do not use fabric conditioner on cloth nappies, because it makes them less absorbent and that can lead to nappy rash.

Official NHS wording is an evidence statement about irritation, not a personalised dermatology verdict. If skin is broken, bleeding or not settling, that is a clinical question for a GP, health visitor or NHS 111 — not a detergent brand debate.

Why does The Nappy Lady still default to non-bio?

The Nappy Lady's bio v non-bio note (2016, still published) is explicit: they do not default to bio as standard, even after the NHS skin wording changed. Their reasons are fabric and warranty, not a claim that enzymes irritate skin.

• Warranties. Some UK makers have, at times, specified non-bio powder. Using bio can put you outside that care label. The 2016 note named examples then current; check today's booklet, not a forum memory.
• Cellulase. That enzyme class is designed to snip tiny cellulose fuzz. Cotton, bamboo viscose and hemp are cellulose. The Nappy Lady's cited textile interview said cotton will not fall apart on wash one, but wear can show over time. Cloth nappies are washed far more often than a T-shirt.
• Mixed loads. A typical stash mixes microfibre (synthetic, not eaten by cellulase) with cotton or bamboo nights. Their advice is one simple non-bio routine rather than splitting the wash.
• Stains. They accept that bio often removes stains better. Their alternative for yellow breastfed marks is sun on a damp nappy, not a clinical claim.

If someone has to use bio (it is what the shop sells), The Nappy Lady's own workaround is: check the warranty, then look for a bio that lists enzymes and does not list cellulase. They do not publish a brand list because formulas change.

What does Clean Cloth Nappies say enzymes are for?

Clean Cloth Nappies (CCN) is the other widely cited school. Their detergent page, reviewed by chemists on their team, argues that ammonia from poorly washed wee is the destructive chemical, not mainstream surfactants, and that restrictive 'no enzymes / no oxygen bleach' maker lists are often leftover myth.

CCN quotes the NHS enzyme line and says most supermarket detergents can be used on cloth nappies. Their wash-performance levers are dose for a heavy or hard-water load, a warm main wash (they discuss 40–60°C), and enough time — not switching to a specialist 'baby' bottle. Fragrance is a separate issue: some people react to perfume in detergent; that is not the same as the enzyme debate.

How do I decide from the nappy in my hands?

Work from the product you own, not from a social-media team.

1. 1
   Photograph the care label and any warranty card Look for the words biological, non-biological, enzymes, bleach, or a named detergent type. If the label forbids bio or names non-bio only, that is the instruction that can affect a claim — whatever a Facebook group prefers.
2. 2
   Name the fabrics in the wash All-microfibre or all-synthetic inserts are the group The Nappy Lady says are not affected by cellulase. Cotton, hemp and bamboo viscose are the cellulose group their cited textile advice treats as more vulnerable over many washes.
3. 3
   Separate skin from cleaning If the question is 'will bio powders irritate skin more than non-bio?', the NHS evidence statement is the official line. If the question is 'will this void the warranty or wear the bamboo?', the maker and The Nappy Lady's fabric argument are the relevant school.
4. 4
   Skip fabric conditioner on cloth That is an NHS cloth-nappy rule about absorbency and nappy rash, independent of bio versus non-bio.

In shortIn short: NHS = no evidence enzymes irritate skin more than non-bio. CCN = enzymes help clean; dose and temperature matter more than the baby-aisle label. Nappy Lady = non-bio as the simple default because of warranties and cellulase on natural fibres. The care label is the tie-break for the nappy you already bought.

Is this the same question as smelly cloth nappies?

No. Smell, ammonia and leaks are a wash-performance problem: dose, temperature, how long nappies sit wet, and whether conditioner has coated the fabric. CCN's detergent page treats leftover wee that becomes ammonia as the thing that damages both fabric and skin comfort. Switching bio to non-bio, or the other way, without changing dose or temperature is a different slice.

This article stops at the labelled disagreement. It does not invent a league table of UK powders or a rash treatment plan.