Restylane Under Eyes: 3 Month Post Injections Sudden Onset Swelling and Burning Pain?

When other posters indicated that this is very, very rare, that is true.  Recurrent swelling can be associated with the menstrual cycle for some individuals although this is also rare.  However, when there is redness and pain in association with redness, this could represent a skin infection or cellulitis.  Antibiotic treatment is prudent under these circumstances.  In situations were there is a frank infection, removal of filler with enzyme may be indicated.  This situations while extraordinarily rare can still occur.  If you doctor can't figure it out, it is because they have never seen it before and does not know what to make of this.  If this issue persists, I would recommend removing the filler with enzyme.  This is unlikely to represent an allergy to product because one would not expect an allergy to resolve.

Anecdotally, early batches of Juvederm were associated with persistent swelling in about 30% of patients.  It was unclear exactly what caused this swelling but it would resolve after about 3 to 6 weeks.  The incidence of this type of reaction now seems much less common.

Follow up with your medical provider for a re-evaluation, he/she can possibly dissolve the product using an enzyme called hyaluronidase

It sounds like you need to re-visit your provider and ask for their help in dissolving the product with hyaluronidase (if it is product that's causing the discomfort/issue). It's very uncommon to have a specific allergy to the product and what you're describing doesn't sound like an issue with filler, especially this far post-treatment.