Can you get an allergic reaction to filler 5 months after treatment and how long will the filler last?

An allergic reaction would be unusual 5 months after, but not impossible. It sounds more like a delayed reaction/infection and the treatment seems appropriate. Follow up frequently with your injector for this to resolve appropriately. Good luck, Dr. ALDO 

Thank you for sharing your question and I am sorry to hear of your infection and swelling.  It would be very unusual for a filler to become infected or cause an allergy after such a long time but it appears that you received the appropriate treatment. I would continue to follow up with your injector until the swelling in your face completely resolves.

Thank you for your question. It is unusual to have an allergic reaction after 5 months but not impossible. From your description, it seems like you had delayed reaction (infection). I would continue following up with your treating physician as he/she may want to continue to dissolving the filler and treating your issues. Best of Luck!

You are likely having a delayed reaction to the filler. I would continue to follow up with your treating physician to continue to work on dissolving all the filler and treating the continuing issues.  Good luck with your recovery.

As you have already had the appropriate treatments to dissolve the filler etc. you should return to see your practitioner for further assessment and keep a 'diary' of your problem so that they have a clear understanding of what is actually occuring under your eyes.