It is thought that between a third and a half of all medicines prescribed for long‑term conditions are not taken as recommended. If the prescription is appropriate, then this may represent a loss to patients, the healthcare system and society. The costs are both personal and economic.
Adherence presumes an agreement between prescriber and patient about the prescriber's recommendations. Adherence to medicines is defined as the extent to which the patient's action matches the agreed recommendations. Non‑adherence may limit the benefits of medicines, resulting in lack of improvement, or deterioration, in health. The economic costs are not limited to wasted medicines but also include the knock‑on costs arising from increased demands for healthcare if health deteriorates.
Non‑adherence should not be seen as the patient's problem. It represents a fundamental limitation in the delivery of healthcare, often because of a failure to fully agree the prescription in the first place or to identify and provide the support that patients need later on.
Addressing non‑adherence is not about getting patients to take more medicines per se. Rather, it starts with an exploration of patients' perspectives of medicines and the reasons why they may not want or are unable to use them. Healthcare professionals have a duty to help patients make informed decisions about treatment and use appropriately prescribed medicines to best effect.
There are many causes of non˗adherence but they fall into two overlapping categories: intentional and unintentional. Unintentional non˗adherence occurs when the patient wants to follow the agreed treatment but is prevented from doing so by barriers that are beyond their control. Examples include poor recall or difficulties in understanding the instructions, problems with using the treatment, inability to pay for the treatment, or simply forgetting to take it. Intentional non˗adherence occurs when the patient decides not to follow the treatment recommendations. This is best understood in terms of the beliefs and preferences that influence the person's perceptions of the treatment and their motivation to start and continue with it. It follows that to understand adherence to treatment we need to consider the perceptual factors (for example, beliefs and preferences) that influence motivation to start and continue with treatment, as well as the practical factors that influence patients' ability to adhere to the agreed treatment.
Applying this approach in practice requires:
a frank and open approach which recognises that non˗adherence may be the norm (or is at least very common) and takes a no˗blame approach, encouraging patients to discuss non˗adherence and any doubts or concerns they have about treatment
a patient˗centred approach that encourages informed adherence
identification of specific perceptual and practical barriers to adherence for each individual, both at the time of prescribing and during regular review, because perceptions, practical problems and adherence may change over time.
This guideline makes recommendations about how healthcare professionals can help patients to make informed decisions by facilitating the involvement of patients in the decision to prescribe, and how they can support patients to adhere to the prescribed medicine. We have not made separate recommendations for carers and families. The principal relationship is between patient and healthcare professional, and the patient has a right to decide who should be involved in their care. With the patient's consent, carers should have access to appropriate levels of information and support.
An increasing number of healthcare professionals are now involved in the prescribing, dispensing and reviewing of medicines. It is not within the remit of a guideline to recommend which healthcare professional carries out these roles. All healthcare professionals should be aware of and work within legal and professional codes. Information and tools are available to support healthcare professionals.
 In this guideline 'medicines' is used as a general term to refer to prescribed medicines that are self-administered and includes tablets, syrups, ointments, eyedrops and suppositories.