The first answer for how you treat a lumbar herniated disc is that you don't. A number of people will have disc herniations and not have any symptoms from those herniations, so just because you see a disc herniation doesn't mean it's necessarily symptomatic. You have to put the MRI findings in the proper context and that context is in the presentation of the entire person.
The goal of treating a symptomatic lumbar herniated disc is to relieve the inflammation from the herniation and then to get the mechanics of the spine right to take the pressure off the disc herniation to allow it to reabsorb, to scar down, to stop being symptomatic.
This generally starts with exercise, physical therapy, stretching and strengthening the muscles in an appropriate way to help to unload the spine to allow the disc to, essentially, heal itself.
Along the way there are oral medications that may be helpful to address the symptoms that are going on, which will allow someone to continue with physical therapy and to make people feel better as they're going through the process of getting better.
There are also modalities within physical therapy itself that are more passive like traction, like TENS units and ultrasound, electrical stimulation, manual manipulation, passive modalities that are designed to help control the symptoms and also to help decompress the spine in order to take away some of the inflammation as well.
When the pain is persistent, when the symptoms are persistent - and they could be pain, numbness, sometimes weakness - when those symptoms are persistent they're not getting better with therapy, or if the symptoms are so great that they are interfering with a person's ability to function or ability to participate with physical therapy, then sometimes an injection, an epidural steroid injection around the symptomatic herniated disc can be very effective in helping to take away the inflammation and the swelling from around the nerve root and the disc in order to open up this "window of opportunity" during which the inflammation is gone. The disc may still be herniated, but the inflammation will -- you know ideally won't be there - and we can take that as a "window of opportunity" to stretch and to strengthen and to tweak the mechanics so that we're not sitting back there again having to do any more injections in the future because now the mechanics have been shifted.
When aggressive conservative treatments fail and the symptoms from the disc herniation are interfering with a person's quality of life, there are good surgical alternatives, including a simple discectomy to basically take out a piece of the disc in order to decompress the spine and take the pressure off the nerve. It's always good to have a full conversation of all the surgical alternatives with a spine surgeon if conservative care is not taking away the symptoms.