I have been on teriparatide injections for nearly a year now. Sometimes I get that pain in my back which lasts for about 15 mins and sometimes I don’t. The staff at the endocrine dept of a large teaching hospital which look after me told me that it is nothing to worry about and apart from the brief discomfort there doesn’t seem to be.
Sometimes a very small blood vessel can be caught by the needle as it is injected because they are difficult to see and avoid. There can be a tiny bit of bleeding and a bruise. I have done this several times but nothing to worry about. You will get used to having your injections and I hope that over the two years it helps with your bones.