Medication-Induced Taste Disorders

Taste disorders are relatively common and can significantly affect quality of life. There are many types of taste disorders, including:

• Dysgeusia – distortion of normal taste;
• Hypogeusia – reduced or diminished sense of taste;
• Ageusia – a complete loss of taste;
• Aliageusia – when a typically pleasant-tasting food or drink begins to taste unpleasant; and
• Phantogeusia – tasting something that is not actually there, also known as phantom taste perception.

While the exact prevalence is unknown, the literature reports rates ranging from 0.6% up to 20%. The prevalence may be much higher in some patient groups, with up to 76% of people receiving cancer treatment reporting some disorder of taste. These disorders are particularly common in cancer patients undergoing radiotherapy of the head and neck.

However, a wide range of other factors can contribute to taste disturbances. This includes xerostomia, heavy smoking, nutritional deficiencies, COVID-19, and various other medical conditions. As taste and smell are closely linked, patients may report a taste disorder when the primary dysfunction is actually olfactory.

It is important to consider the potential for medications to affect taste. One report found that medications were responsible for around a quarter of all cases of taste disturbance.

Implicated medications:

When thinking of medications that affect taste, anticholinergics may be the first that come to mind due to their propensity to cause dry mouth. The number of medications with anticholinergic properties is large, and their effects are additive. Many other medications can also cause taste disturbances via different mechanisms; in many cases, the precise mechanism for their effect on taste is not known.

A small sample of medications associated with taste disturbances is shown in Table 1.

Table 1. Medications associated with taste disturbances

Potential consequences of taste disturbances:

Taste disturbances may not seem like a particularly significant issue beyond reducing the enjoyment of food. However, there are some potentially serious consequences that should be considered.

Patients affected by this condition may end up reducing their food intake due to decreased enjoyment of eating. This may lead to nutritional deficiencies and unintended weight loss. Other patients may attempt to improve the flavour of their food by adding large amounts of salt or sugar or significantly increasing their fluid intake to mask unpleasant tastes or soothe a dry mouth. These coping strategies could result in increased urinary frequency (which could potentially contribute to urinary incontinence or increased falls risk) or exacerbate underlying conditions such as hypertension and diabetes. The onset of taste disturbances may also affect medication compliance, which can interfere with the management of chronic conditions.

The elderly are more likely to experience medication-induced taste disturbance due to higher rates of polypharmacy in this population. The potential consequences may also be more serious in this group due to higher rates of underlying frailty and comorbid conditions.

Taste disturbances and related disturbances of smell can also have more acute consequences. For example, taste disturbances may reduce the ability to detect if a food is spoiled, while smell disturbances may make it difficult to detect airborne dangers such as smoke and gas leaks.

Management of taste disturbances

Understanding the potential for medications to cause disorders of taste is important when considering a management strategy. Ceasing the drug responsible for the condition is likely to resolve the problem, but may not provide immediate relief. However, it is not always appropriate to cease a therapy. Changing to a different medication from the same class may be an option. For example, enalapril is less likely to affect taste than captopril.

If changes to the medication therapy are not possible, consideration of other options may be required. Unfortunately, there is not a lot of evidence to guide treatment in this area, but options that could be explored include improving oral hygiene, zinc supplementation, and saliva substitutes. There is trial data to support the use of the antioxidant, alpha lipoic acid. However, further studies have produced mixed results for this therapy.

For therapies that are highly associated with taste disturbances, such as cancer therapies, it is useful to provide patients with clear information about the risks and potential management strategies. The Cancer Council Australia provide patient information on how to manage taste and smell changes during cancer therapy. Early referral to a dietician may be required for patients at particular risk of nutritional deficiencies.