Gluten free or gluten-free

[ChimChimeny]

I'm checking something for work and someone has written gluten-free, but I don't think you need the hyphen. Who's right?!
TIA

Schar call their products Gluten-free.
The NHS do a Gluten-free diet sheet.
www.nhsinform.scot/healthy-living/food-and-nutrition/special-diets/gluten-free-diet

I never noticed it was hyphenated before!

The GF products I have in my freezer do not have a hyphen but they are not from GF companies.

Weird, so could be either!

Who knew 😁

Thanks

Coeliac UK website doesn't use a hyphen.
Quick look at my free from products from various manufacturers don't use a hyphen.

Definitely hyphenated. Most organisations can't be bothered though. Or don't know.

I would choose to put a hyphen in gluten-free, if I were writing it, the same as I would for fat-free, down-sizing, and other examples which I can't think of at present.

It doesn't really matter and there are no hard and fixed rules. Some compounds even change, depending on what comes after them.
General rule of thumb though is that if it's a noun+adjective followed by another noun (as in gluten-free product) then you would use a hyphen. But nobody would be correct in saying you were wrong if you didn't. The hyphen is just a visible "tool" to guide the reader through a complex sentence.

It doesn't really matter

It actually did in this instance, something I was working on will be out in public & I wanted to make sure it is correct.

Depends whether it’s post-positive, I think the term, is, but it’s very much a style point. Eg:
The meal was gluten free.
It was a gluten-free meal

What @Teeshirt said. Same as eg “long-term relationship” and “the relationship was long term”.

Yes, that's the general "rule", though "rules" for compounds are very subjective and even published grammar and spelling books/dictionaries don't always agree. Corpus studies even less so.

But rule of thumb is that if you're forming a compound with a noun+ adjective that goes on to modify another noun, common practice is to hyphenate. Not hyphenating isn't wrong though.

It truly doesn't.
Common practice isn't a rule.

@PAFMO , what's a corpus study, please? (Hears English teacher saying, "Look it up, girl.")

I'd hyphenate it, because I would hyphenate fat-free.
If you offered someone a fat free meal it could be a large meal offered as a gift, not a meal containing no fat.

Yes, but if it was a meal that was fat free, that doesn’t have the same ambiguity, and that’s why whether or not a hyphen is used can vary, depending on the sentence construction. I am an editor and our policy would be “fat-free meal” and “the meal is fat free”. Other editorial policies will vary.

It needs a hyphen for clarity.

For example, imagine a restaurant with gluten free for all.

@Teeshirt , I'd hyphenate in 'a meal that is fat-free' to eliminate the possibility of confusion. I am an editor.

hyphen required!

They'd be welcome to all the free gluten.

I'd stick to the gluten free menu/choices. Or eat somewhere else...

Coeliac here and would normally just write gluten free without hyphen but not sure of the technicalities?! 😂