Hypoallergenic hair dye labels, and PPD vs PTD

The short version

Hair dye labels carry three kinds of wording: legally required cautions, ingredient lists, and marketing claims such as “hypoallergenic”, “PPD-free”, “ammonia-free” and “natural”. The sources we read give the first kind some force, let you decode the second, and say little that helps with the third. This page covers that gap and does not repeat the PPD material in What is PPD in hair dye?, which holds the dermatology sources, the studies and the FDA warning text. We work from documents, have not tested any product, and this is not medical advice.

What “hypoallergenic” on a dye box means

The FDA’s page on “Hypoallergenic” cosmetics (retrieved 2026-11-14) says hypoallergenic cosmetics are “products that manufacturers claim produce fewer allergic reactions than other cosmetic products.” It then says: “There are no Federal standards or definitions that govern the use of the term ‘hypoallergenic.’ The term means whatever a particular company wants it to mean.” It adds that makers are not required to submit substantiation of the claim to the FDA, and that dermatologists say the term has very little meaning. A fuller version of this point is in what “hypoallergenic” means.

For hair dye the claim sits on top of an unusual regulatory position. The FDA’s Hair Dyes page (retrieved 2026-11-14) says most hair dyes are “coal-tar” hair dyes, covering permanent, semi-permanent and temporary dyes, and that unlike color additives in general they do not need FDA approval. It says the agency’s ability to act against coal-tar hair dyes tied to safety concerns “is limited by law”, so consumers should follow the label directions.

“PPD-free”, “ammonia-free” and “natural”

We did not find a readable regulator or standards-body definition of any of these three claims for hair dye. The FDA’s Cosmetics Labeling Claims page (retrieved 2026-11-14) is general: it says the FDA has no list of approved or accepted claims for cosmetics, that labelling claims must be truthful and not misleading, and that FDA regulates labelling claims while the Federal Trade Commission regulates advertising claims. It does not mention hair dye or these phrases, so we read it as context only.

What the sources do say bears on “PPD-free”. A 2025 abstract in Cutis (PMID 41524634) says toluene-2,5-diamine sulfate “is widely used as an alternative to para-phenylenediamine (PPD) in hair dyes but is itself a potent and likely underreported contact allergen”, with common cross-reactivity with PPD. A 2026 abstract in Dermatitis (PMID 41649178) reports co-sensitisation between PPD and related compounds, including 4-aminophenol and 3-aminophenol, among patients at one clinic. So a PPD-free front label tells you one ingredient is absent, and tells you nothing about its replacement. We found no source on whether such dyes cause fewer reactions, and we make no claim either way.

We found nothing on “ammonia-free” or “natural” beyond the EU glossary, which lists AMMONIA (entry 1709). That confirms a name, not any property of the claim.

PPD vs PTD, and the other names to look for

PTD is a common short name for toluene-2,5-diamine, and PPD for p-phenylenediamine. The EU glossary of common ingredient names, Commission Decision (EU) 2019/701 (retrieved 2026-11-14), contains these entries, each found by searching its text:

Ingredient (EU glossary name)	Entry number
P-PHENYLENEDIAMINE (PPD)	20428
P-PHENYLENEDIAMINE SULFATE	20430
TOLUENE-2,5-DIAMINE (PTD)	25116
TOLUENE-2,5-DIAMINE SULFATE	25117
RESORCINOL	21173
2-METHYLRESORCINOL	289
P-AMINOPHENOL	16528
M-AMINOPHENOL	13888
AMMONIA	1709
ETHANOLAMINE	8658
HYDROGEN PEROXIDE	10788
HENNA	10281

An exact entry for “LAWSONIA INERMIS” was not found in the glossary text. The glossary confirms that these names exist for EU labelling. It does not say what any ingredient does in a dye, how much a product contains, or whether it is an allergen, and we read nothing that does for resorcinol, the aminophenols, ammonia or ethanolamine. Only PPD, toluene-2,5-diamine and 4- and 3-aminophenol appear in the dermatology abstracts above, and only as described there. The sources we read say nothing about wording on US labels, so we state no US names.

The patch test on the box

Two sources describe it. The FDA says it cannot act against a coal-tar hair dye on the ground that it is or contains a harmful ingredient as long as the label carries a specific cautionary statement and the product comes with adequate directions for a skin test before dyeing. The wording of that statement is in our PPD guide. DermNet says hair colour preparations containing PPD or its derivatives carry a warning recommending a self patch test, and that a negative result before use does not rule out a reaction, because “the patch test itself could cause sensitisation” and a rash could follow at the next dyeing.

We read the FDA text as a condition for how the product is labelled, not as medical guidance on how to test your skin, and we read no instructions for performing the test. If you have reacted to dye before, or are unsure, a dermatologist is the person to ask, including about clinic patch testing, which is a different procedure from the box test.

Henna and “black henna”

The FDA page on henna and “black henna” tattoos could not be retrieved, so we cite no FDA position on henna, hair or skin. The EU glossary lists HENNA (entry 10281), which tells you the name to look for and nothing about purity.

What we did read is limited to PPD. DermNet says high concentrations of PPD in black temporary tattoos “may result in intense blistering reactions” at the tattoo site within 1 to 2 days, with a lichenoid eruption possible 1 to 2 weeks later. The PPD guide cites a 2010 abstract on tattoo sensitisation and later hair dye reactions. Nothing we read says which products sold as henna contain PPD, so the ingredient list is the only label evidence we can point to here, and for any past reaction, a dermatologist.

Why this site has no hair dye roundup

The roundups on this site list only products with a maker’s published ingredient list, or matching listings from two independent retailers, retrieved on a stated date. For hair dye, fewer than two products reached that bar, so a roundup would have rested on claims we could not check. We would rather say that than rank products on front-label wording the FDA says is undefined. This is our own editorial rule, not a regulation or a medical judgement. It also means we have named no dyes, good or bad.

Where to go next

For the dermatology sources, the PTD studies and the FDA warning text, read What is PPD in hair dye?. Other personal-care pages: hypoallergenic shampoo, hypoallergenic eyelash glue, hypoallergenic mascara, hypoallergenic makeup, hypoallergenic lotion, hypoallergenic products on a budget and hypoallergenic travel essentials. For metal allergy rather than dye allergy, see nickel allergy and jewelry.

If you have had a rash from hair dye, a reaction to a black temporary tattoo, or work with dye, ask a dermatologist. Diagnosis and patch testing are clinical matters.