I have a bulging vein in the middle of my forehead. What type of treatment should be used? (photo)

There are many good options for treatment of forehead veins but the one you show in your picture can be treated safely and effectively with sclerotherapy.Contact a vein specialist for guidance. 

There are several methods that can be used to treat facial veins, including sclerotherapy and lasers. It is best to get evaluated by a board-certified vein expert to determine which vein removal treatment is best for your situation.

Forehead veins can be safely treated.  The veins in the picture are large and can be treated either by sclerotherapy or removal through small incisions (microphlebectomy). Each method had pros and cons.  Discuss this with your treating physician.