Most people take Actemra for up to 1 year to treat Giant cell arteritis (GCA), although the exact length of time you will take it for depends on how well you tolerate any side effects of Actemra, if it works for you, and how long it continues to work for. Actemra will work within 3 to 6 months, if it is going to work at all, although some people may experience some symptom relief as early as 2 weeks after starting treatment. Actemra is given by subcutaneous injection once every 1 to 2 weeks.