PATIENTS who visited a North-East pharmacy during the last week are being urged to check their medicines after a higher strength version of a medicine was accidentally sold to patients over the counter.

Six boxes of co-codamol effervescent 30/500 tablets, which come in a maroon and white box with a Zanza Pharmaceutical logo were accidentally sold to patients from the Neville Pharmacy, on Neville Parade in Newton Aycliffe, County Durham between Wednesday 7 November and Tuesday 13 November 2012.

The six boxes are a higher strength version of the tablet which is normally available over the counter and may cause side effects, including constipation, nausea, vomiting, dizziness, light-headedness and drowsiness.

The affected boxes contain pills made up of 30mg of codeine with 500mg of paracetamol when the normal over the counter dose is 8mg of codeine with 500mg of paracetamol.

It means that each pill has more than three times the amount of codeine than the over-the-counter version.

Dr Ian Davidson, controlled drug accountable officer, at NHS County Durham and Darlington said: "We are working with the pharmacy to resolve this issue and would advise any patient who may have purchased these tablets to return them to Neville Pharmacy as soon as possible.

"Should anyone have any concerns about their health, they should contact their GP in the first instance, their local pharmacist or contact the NHS 111 urgent health care line, which is free to call from landlines and mobile phones."