Tell me about pain medication like aspirin and codeine?

Dose dependent: Aspirin is good for mild pain, treats fever, and acts as an anti-inflammatory agent when used chronically. As the dose is increased, there is progressive issue with upset stomach and peptic ulceration. Codeine is good for moderate pain. As the dose is increased, it causes nausea and constipation. It is addicting. The drugs are combined to get a better total effect at lower doses.