8 days post op arm lift. Is it normal to have my skin black by the stitches? (Photo)

It is imperative that you follow up with your board-certified, plastic surgeons immediately! These results are NOT typical.Every plastic surgeon's postoperative instructions are different.  It is very important that you follow your plastic surgeon's instructions implicitly.  If you were my patient, I would recommend oral antibiotics, applying topical antibiotic cream, and minimal arm compression. I would suggest elevation of hands above your heart. I would not recommend showering. You may require local wound debridement in the office.I hope this answers your question regarding arm lift or brachioplasty wound treatment.Sincerely, Dr. Katzen

Those black areas could just be dried blood over the wounds but its very hard to tell from the photos. I would make a follow up appointment with your surgeon so he/she can examine you more closely.

Speak with your plastic surgeon to discuss your concerns and progress as they are in the best position to advise you about your individual recovery.  Its hard to determine from photographs alone but you may have poor blood circulation to the skin on the incision due to tension placed on the skin.  

A combination of things are happening at the incision site.  Some of the discoloration is superficial tissue changes that will improve with time. Sometimes the discoloration is from poor circulation to the skin at the incision. This could be secondary to the tension placed on the closure.  The best thing to do right now is just allow it to heal and keep the area clean.  Make sure your surgeon is evaluating the incision often to make sure that it does not get infected. Worst-case scenario you might be looking at a office procedure to revise  the scar down the road. 

I am sorry that you are going through this inconvenience with your surgery.Answering your question:the changes in your skin might be due to blood flow restriction that might be secondary to the tension of removing the excess skin.I notice that there might be some redness associated to the skin changes.Make sure to keep your surgeon informed of this changes so that he can guide you in the best way to prevent major complications.best wishes.

Your skin was closed tighter than ideal and some of the darker skin does not have enough circulation.  I'd put some burn cream like Silvadene on it until it heals or consult with your surgeon.