If you have dealt with cellulitis more than once, you already know that the standard advice — treat it fast, keep your skin clean, avoid cuts — only goes so far. For many people, the infection keeps returning despite doing everything right.

You noticed it as a red, tender cord along your leg — warm to the touch, sore when you press it, and stubborn enough to last for days or even weeks. Superficial thrombophlebitis is one of those conditions that gets dismissed as minor but rarely feels minor when you are living with it.