But there is evidence that with each rise in prescription charges more and more patients are being forced to limit their medication. This April the cost of a prescription rose by 10p to £6.30 in England. This is the fifth year in a row that the rise has been 10 pence.

A recent report by the BMA stated that, "All GPs have anecdotal evidence of patients asking which of two or more items on a prescription form are the most important as they cannot afford to pay for more than one at a time."

Of course not everybody is forced to pay for their prescriptions. The system of exemptions has been reviewed several times and currently includes: people under 16 years of age, people under 19 years of age if they are still in full time education, people aged 60 or over, people receiving income support or family credit, and their dependants, people who qualify for exemption from NHS charges on low income grounds and their dependents and pregnant women or women who have a child under one. Patients are also entitled to a free prescription if they hold an exemption certificate issued by a health authority because they suffer from one of a number of specified medical conditions, such as diabetes and hypoparathyroidism.

This system of exemptions creates a number of problems and anomalies. For example, women are exempt for the duration of pregnancy and for a year afterwards. But exempting women for a year after birth is no longer necessary as very few women now suffer health problems in the year after giving birth.

Some of those requiring lifelong treatment, such as those with cystic fibrosis and Parkinson's Disease, are more deserving of free prescriptions than some of those currently entitled to them. The BMA has highlighted the anomalous position of the exemption applying to all prescribed items for patients in the "chronic sick" list. For example, the system allows a diabetic with chronic bronchitis to be exempt from all charges whilst a chronic bronchitic with heart failure must pay for all prescriptions.

A number of patients are not exempt from prescription charges even though they require regular medication, such as those suffering from Asthma. The National Asthma campaign says, "People with asthma are telling us that they cannot afford to pay for their prescriptions. They are limiting their asthma medication and putting their health at risk. Incorrect asthma treatment can increase the frequency of asthma attacks and lead to irreparable damage to the lungs."

The National Asthma Campaign argues for better promotion of the pre-payment scheme which currently exists, and the introduction of a spread payments scheme to make pre-payment more accessible. Prescription pre-payment certificates are available for those who do not qualify for charge remission but who need a lot of medication. Certificates went up in April this year from £32.40 to £32.90 for 4 months and from £89.00 to £90.40 for 12 months.

The government's aim to introduce e-prescribing by 2004, as set out in the NHS plan, may be the catalyst for changes in the charging system. Derek Wanless said in his report on the future of the NHS that investing in IT would "lay the basis for the delivery of cost savings over the next 20 years". These cost savings could lead to a fairer system of prescription charging. E-Prescribing could help combat prescription fraud which currently costs the NHS £100 million a year. With e-prescribing the government would have a method by which it could control the NHS formulary and, when there is an alternative drug, enforce the substitution of the cheaper generic version.

Of course prescription charges raise a significant amount of money for the NHS. In 2003-2004 prescription charges are expected to raise some £446 million. But although around four out of five prescriptions are exempt from charges it is those who just fail to meet the exemption criteria who are particularly badly hit.