Despite anecdotal evidence that the triamcinolone jab works wonders, there really is no proper evidence base that it is more effective than systemic antihistamine tablets with topical treatment where required.
Combine that with the potential nasty side-effects, most notably subdermal fat necrosis leaving dents in your appearance, and it is clear why they are abandoned as treatment for a 'benign' condition such as hayfever.
The situation in the UK is such that anyone who administers these jabs for this indication has no indemnity insurance.