Dry mouth

The most common adverse effect of many medications is dry mouth (hyposalivation or xerostomia). The reasons for this vary from medication to medication but can range from dehydration (eg, with diuretics) to anticholinergic activity (eg, with some antidepressants).

Dry mouth has a number of consequences, including altered taste, increased risk of fungal infection, increased caries risk, and increased prevalence of traumatic ulceration due to lack of lubrication. Patients with severely impaired salivary flow also have difficulty with eating, swallowing, and speech. The former can result in decreased food intake and poor nutrition.

Numerous management options are available for decreased salivation, which are beyond the scope of this chapter. These range from the simple, such as increased hydration, to the complex, such as systemic procholinergic agents to increase salivary production.

Lichen planus

Many medications can produce mucosal reactions that are indistinguishable both clinically and microscopically from lichen planus. Although this is often the classic reticular form, it may also appear ulcerative or erosive. Biopsy is warranted to verify diagnosis. The association with medication is made primarily by history and temporal association between the lesions and starting the offending medication. In rare circumstances, the lichen planus can become extensive or painful enough to warrant changing the culprit medication. Common drugs that cause lichenoid reactions include ACE inhibitors, beta-blockers, NSAIDs, diuretics, hydroxychloroquine, and others.

Inhaled steroids

A frequent complication of inhaled steroids is candidiasis (sometimes called thrush). Patients experience overgrowth of Candida species in correlation with the dose and the frequency of the steroid use. This growth is due to inhibition of the patient's normal immune function, altering the normal equilibrium in favor of the yeast. Oral candidiasis is characterized by small, curdy-appearing whitish papules and plaques that can usually be wiped from the mucosa. The tissue beneath these plaques is often inflamed and may bleed. The infection is usually self-limiting, so steroid use can still continue. To prevent further exacerbations, adding a spacer to the inhaler, decreasing the frequency of steroid use, and rinsing the mouth after taking the steroids are recommended.

Gingival enlargement (hyperplasia)

Gingival enlargement (often referred to as hyperplasia even though it is not a true hyperplasia) may occur because of congenital abnormalities, hormone abnormalities, or certain medications. The 3 most common drugs that can produce dramatic gingival hyperplasia are phenytoin, calcium channel blockers, and cyclosporine. A preexisting condition of gingival inflammation, resulting from poor oral hygiene, can predispose the patient to, or exacerbate, existing enlargement.

Gingival hyperplasia develops in approximately half the patients taking phenytoin. Gingival enlargement due to nifedipine use has an approximate prevalence of 38%, and the prevalence of cyclosporine-associated gingival hyperplasia varies from 13-85%. The anterior gingiva is the most common site of enlargement, although it may occur anywhere. Changes typically begin in the first 3 months after the initiation of therapy, but they may develop within 2 weeks. As growth continues, gingival tissue may extend and nearly cover the facial surface of the crowns. The histologic features of phenytoin hyperplasia include increased amounts of connective tissue, an absence of vascular changes, and decreased epithelial thickness. Lymphocytes and plasma cells may be present because of increased plaque around the gingiva.

Closely monitored oral hygiene is essential to reduce the prevalence of gingival hyperplasia. Discontinuing the medication or changing to an alternative medication within the same drug class may reduce hyperplasia, but spontaneous remission or regression of the condition is rare. Azithromycin may reduce gingival hyperplasia due to cyclosporine therapy. Therapy usually involves conservative surgical excision of the excess tissue using a scalpel, electrosurgery, or a laser. This helps to improve the cosmetic appearance for the patient and facilitates good plaque control. The gingival tissue continues to regrow, however, and patients typically need repeated surgeries for as long as they are on the offending medication.