Many people forget to take a dose of their medication occasionally. Drug nonadherence, not taking medications as prescribed, is common, dangerous, and costly. In this Special Feature, we outline some reasons and possible solutions.

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According to some estimates, around 40–50% of people do not take medications to manage chronic conditions as prescribed.

Why is this figure so high? In this Special Feature, Medical News Today explores the complex reasons for drug nonadherence and the negative effects — on people and the healthcare system.

Good medication adherence involves taking prescribed medications according to the instructions of a healthcare professional. In many cases, this means taking at least 80% of prescribed doses.

More broadly, the World Health Organization (WHO) defines adherence as the “extent to which a person’s behavior — taking medication, following a diet, and/or executing lifestyle changes — corresponds with agreed recommendations from a healthcare provider.”

Medication nonadherence can be unintentional. In other cases, a person may decide not to follow treatment recommendations.

Unintentional nonadherence may involve forgetting a dose, accidentally taking the wrong dose, or taking a dose at the wrong time of day.

Also, it may involve not storing medications properly. Some, for example, need to be refrigerated or stored away from light.

Intentional nonadherence, on the other hand, usually results from a range of personal, medical, social, and economic factors.

A person may decide not to take their medications as prescribed due to a range of factors, including past experiences. Some more common reasons include:

  • Cognitive conditions: Conditions such as dementia and Alzheimer’s disease may cause a person to take their medication in a way other than their doctor has prescribed.
  • Concerns about competence: This might involve not trusting the doctor to make appropriate decisions, possibly because the doctor is unaware or dismissive of cultural factors or personal preferences or beliefs.
  • Concerns about side effects or dependency: A related issue may be feeling overwhelmed by the number of side effects listed on packaging or websites.
  • Denial: A person may not accept that they have a health issue that requires this treatment.
  • Depression: People experiencing depression are less likely to take medications exactly as prescribed, the American Medical Association report.
  • Drug or alcohol use: This can cause a person to take their medication in a way other than their doctor has prescribed.
  • Lack of symptoms: If symptoms are not present or resolve during treatment, a person may stop their treatment or alter their dosage — especially if the treatment is expensive, hard to take, or causes side effects.
  • Lack of motivation: This can lead to changes or gaps in a treatment plan.
  • Negative experiences: These might involve having side effects of similar treatments in the past. Or, not seeing results may cause a person to stop the treatment.
  • Physical impairment: A person with vision or hearing loss or trouble swallowing, for example, may find it very challenging to take their medication as prescribed.

The cost of medications is a key reason for nonadherence.

Many drugs are very expensive, even for people with good health insurance. High costs may lead many people to ration medications or never fill prescriptions.

A person may be unable to access treatment that their insurance plan does not cover. Also, some drugs may be unavailable regionally.

Many other factors that contribute to treatment nonadherence include:

  • a lack of communication from the doctor
  • an unsatisfying doctor-patient relationship
  • a lack of consistent medical care
  • limited access to medical care and facilities
  • low expectations of care
  • mistrust based on historical precedents
  • beliefs or experiences of friends or family members
  • a preference for traditional or alternative medicines
  • cultural, ethnic, or religious values and beliefs
  • feeling overwhelmed by the number of necessary medications
  • fear of stigmatization
  • concerns about factors that influence a doctor’s prescribing patterns, such as pharmaceutical advertising or financial incentives
  • difficulty or inconvenience
  • a reluctance to make accompanying dietary or lifestyle changes

Tracking the full effects of medication nonadherence is difficult. It is not typically listed as a cause of death, and doctors may never realize how well their patients are complying with instructions.

By some estimates, each year, drug nonadherence causes approximately 125,000 preventable deaths in the United States and $100 billion to $290 billion in avoidable costs. It may also cause up to approximately 10% of hospitalizations annually.

In addition, not taking medications as prescribed for many chronic conditions, such as bipolar disease and depression, can also cause relapses and worsening of symptoms.

An older review, from 2012, found that 20–30% of prescriptions are never filled and around 50% of medications for chronic conditions are not taken as prescribed in the U.S.

One 2016 study found that 35% of people who have kidney transplants do not take antirejection medications as prescribed. Another study, from 2015, reported that most people with asthma take fewer than half of their prescribed doses of controller medication.

Meanwhile, plenty of research shows that medication adherence is associated with a reduced risk of health complications and improved outcomes.

In a 2018 study, for example, medication adherence was associated with fewer symptoms of heart failure and a reduced risk of hospitalization and death.

A 2019 study linked good adherence with a 21% reduction in long-term mortality — and nonadherence with a 17% higher risk of hospitalization — in adults 50 and older.

Health authorities are well aware of the profound damage caused by nonadherence. In 2003, the WHO observed that “Increasing the effectiveness of adherence interventions may have a far greater impact on the health of the population than any improvement in specific medical treatments.”

Improving medication adherence is no easy task. It may involve asking a person to go against their cultural or ethnic practices and may even involve restoring trust in the medical community after years, and generations, of racism and other forms of discrimination.

Also, adherence might involve small changes, such as using an alarm or another medication reminder, but it might involve substantial changes to dietary or lifestyle habits.

Several factors, including education, support systems, medical monitoring, motivation, and evaluations of effectiveness, may be involved in improving adherence.

In one study, researchers found that the rate of hypertension control in a northern California healthcare system exceeded 80% due to a multifaceted approach to improving adherence.

The researchers concluded that the following contributed to the system’s success:

  • an electronic health record that identified people at risk of nonadherence, such as people who made few appointments or did not refill medications regularly
  • outreach to ensure that everyone with hypertension got their blood pressure checked at least once a year
  • staff outreach to people at risk of nonadherence
  • clinical pharmacists who provided advice about adjustments to medication as needed
  • disease-specific education classes
  • individual chronic condition case managers
  • classes and counseling to improve physician-patient collaboration and communication, in an effort to encourage joint decision making
  • well-used guidelines and algorithms for managing disease control — with an emphasis on the use of generic medications to lower cost barriers

Improving medication adherence rates will also likely involve educating the public about the wide-scale, costly, and sometimes deadly risks of nonadherence.

Doctors might also use basic motivational strategies with patients to help increase the odds of medication adherence. In addition, taking a compassionate approach may improve adherence rates. Patient education and empowerment are also critical.

There is a direct link between someone’s view of their need for medication, their sense of empowerment, and the likelihood of medication adherence. Research also shows that an equitable doctor-patient relationship helps improve adherence rates.

Ultimately, doctors and health insurance companies must tackle the problem of nonadherence if real change is to take place.

The good news is that, in nearly all cases, the negative consequences of nonadherence are entirely preventable.

And fixing the problem, in some cases, may be as simple as agreeing to follow a treatment plan as well as possible, as the benefits associated with drug adherence typically far outweigh potential harms.

But because different people have different reasons for not taking medication as prescribed, there is no one-size-fits-all approach to improving adherence rates.

Public health experts have emphasized that focusing on the doctor-patient relationship is crucial. One research paper — published in 2015 — notes that “This unique relationship encompasses four key elements: mutual knowledge, trust, loyalty, and regard.”

Its authors go on to explain:

“Knowledge refers to the doctor’s knowledge of the patient, as well as the patient’s knowledge of the doctor. Trust involves the patient’s faith in the doctor’s competence and caring, as well as the doctor’s trust in the patient and his or her beliefs and report of symptoms. Loyalty refers to the patient’s willingness to forgive a doctor for any inconvenience or mistake and the doctor’s commitment not to abandon a patient. Regard implies that the patients feel as though the doctor likes them as individuals and is ‘on their side’.”

So, each time a doctor prescribes a drug, it is imperative that the patient asks questions and that the doctor takes time to respond thoroughly and aims to understand any obstacles that the patient may face and take steps to address them.