It is an illness which isn't work related. I would expect the first aider to make comprehensive notes but not record it as an accident.
Graham

Agree you don't have to record as they didn't injure themselves but could be classed as a "near miss incident"

At the place I work we record ill health as a separate category on out incident form as we have a fair few members of the public feeling unwell either due to previous medical conditions or from drug or alcohol intake. It means we can keep note of the offices where additional security measures may be required (as people attending also tend to be quite volatile and, given the nature of the work undertaken by our staff can become aggressive). I do record if it's a staff member and if they are off for >7 days look at whether they will require any assistance when they return to work e.g. adaptation to their working environment or tasks undertaken but that's more for an occupational health point of view.

If in doubt, record and that way if it does come back at a later date you have something in writing at your end.

Presumably because making such notes is something first aiders are advised to do during their training. The reason given for this is so they can justify what they did if there are any complaints afterwards.

What First Aid (FA)? There is no mention of FA!

I was stating a fact and not making an assumption!