I've been using retinol from The Ordinary for a while now, but despite using their highest strength I've never had any sort of skin reaction to it - all the advice is to build up slowly so the skin can get used to it, but I've never had even mild redness or irritation. Hard to know if it's made a positive difference either. So I'm presuming I should move on to something stronger now - I think retinal is next, or should I move straight on to tret? And can anyone recommend one that won't break the bank?