The answer to your question depends on what type of pain medication you are taking for your back problems
. There are two common classes of medications that cannot be purchased over the counter that can be taken for back pain. First is the narcotic class. These include medications such as oxycodone (Percocet), hydrocodone (Vicodin), and morphine. There are undesirable side effects of these, but they do not usually damage the liver in a person that starts off with a normal liver. In the short term they cause sedation and constipation. In the long term they cause addiction
and dependence and often require higher and higher doses over time. The second class of medications is the non-steroidal anti-inflammatory medications. Some of these (such as naproxen and ibuprofen) can be purchased over the counter, but the stronger ones require a prescription. Over time they can cause problems such as stomach and small intestine ulcers, and even kidney failure. They are not addictive. Therefore they should only be used for short stretches to control pain.
Since you have chronic pain, I suggest that you schedule an appointment with a pain medicine specialist. This is the type of doctor
most qualified to manage your pain over the long term with as few side effects as possible.