Drug firms told to alert patients.
The Medicines and Healthcare products Regulatory Agency (MHRA) said it was asking manufacturers of painkillers containing codeine and dihydrocodeine to voluntarily update labelling and patient information leaflets.
The updated information will tell patients that taking codeine regularly and for a long time could lead to addiction - causing them feelings of restlessness and irritability when they stop taking the medicines.
It will say that patients should see their doctor or pharmacist if they need to take their over-the-counter medication for more than three days at a time.
The information will also warn that taking the painkiller to ease headaches too often or for too long could actually make them worse.
The MHRA said these precautions could prevent a small number of people becoming addicted to their medication.
Dr June Raine, director of medicines post licensing at the MHRA, said: "Analgesics that contain codeine and dihydrocodeine play a very important part in the treatment of pain.
"Their benefits clearly outweigh any risks, but we still need to highlight those risks to ensure people take their medication safely and correctly.
"We are pleased that the manufacturers are beginning the process of updating their packaging and leaflets to reflect this."
Doctors and health workers have known of the potential for codeine misuse for decades, and most products already contain some warnings in their information