What causes phlebitis with no history of trauma or inactivity. it started in my armpit and now is throughout my arm. i'm prescribed keflex?

Phlebitis: Several reasons for phlebitis. Most common being infection. In arm with no history of trauma or inactivity, it could come from shaving in under arms and infection from the skin of underarms can travel through the lymphatic drainage to the veins daring the arm.

Can be other things.: Other things can cause phlebitis, like bacterial infection which can explain why you are on keflex. Machanical trauma from an IV needle can do it, as can chemicals that cause irritations or burns. Medications, like antidepressants, alcohol, and drugs (opiates) can also do it. Finally, it can be genetic, and run in families. If in your leg, too much standing can do it. See your dr. Fast.