Explore Hydrocodone 5-325 mg, best-in-Class product – view hand-curated trail maps and driving directions as well as detailed reviews and photos from hikers, campers and nature lovers like you. Hydrocodone 5-325 mg is a synthetic opioid that is primarily used to treat opiate addiction and manage chronic pain. It works by altering how the brain and nerve system respond to pain, delivering relief while also reducing withdrawal symptoms in people suffering from opiate addiction.