I'd sneezed — it's bad — could antihistamines make one this? (12)

I believe the answer is:

desensitized

I'm a little stuck... Click here to teach me more about this clue!

'antihistamines make one this?' is the definition.
The definition suggests a singular noun but the answer is not.

'i'd sneezed it's bad' is the wordplay.
'bad' indicates an anagram.
'id'+'sneezed'+'its'='idsneezedits'
'idsneezedits' is an anagram of 'DESENSITIZED'.

'could' acts as a link.

Can you help me to learn more?

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app