Does Prazosin Hydrochloride Cause Dry Mouth?
Yes, prazosin hydrochloride does cause dry mouth, though it is not among its most common side effects. According to the FDA-approved drug label, dry mouth occurs as a less frequent adverse reaction in the EENT (eyes, ears, nose, throat) category 1.
Frequency and Clinical Significance
Dry mouth is listed in the FDA label for prazosin but occurs less frequently than the primary side effects such as dizziness (10.3%), headache (7.8%), drowsiness (7.6%), and weakness (6.5%) 1.
The FDA label specifically categorizes dry mouth under EENT adverse reactions, alongside nasal congestion, blurred vision, reddened sclera, and epistaxis 1.
Prazosin is an alpha-adrenergic blocker, and this drug class is noted to cause dry mouth through anti-adrenergic mechanisms 2.
Mechanism and Context
Alpha-adrenergic blockers like prazosin (along with doxazosin and terazosin) can cause dry mouth as part of their peripheral alpha-antagonist effects 3, 4.
Unlike anticholinergic medications that directly block muscarinic receptors in salivary glands, prazosin's mechanism for causing dry mouth is through alpha-adrenergic blockade rather than anticholinergic activity 2, 5.
This distinguishes prazosin from medications with prominent anticholinergic properties (such as first-generation antihistamines, tricyclic antidepressants, or anticholinergic agents like diphenhydramine) where dry mouth is a much more common and pronounced side effect 3.
Clinical Management Considerations
If dry mouth occurs with prazosin therapy:
Optimize hydration by increasing water intake throughout the day and limiting caffeine consumption 2.
Use saliva substitutes such as moisture-preserving mouth rinses, sprays, or gels with neutral pH 2.
Employ salivary stimulants including sugar-free chewing gum, lozenges, or candy containing xylitol 2.
For severe cases that significantly impact quality of life, systemic sialagogues such as pilocarpine may be considered, though this is rarely necessary with prazosin 2.
Regular dental check-ups are important for patients experiencing chronic dry mouth to monitor for dental caries and other oral complications 2.
Important Caveats
First-dose hypotension is a more clinically significant concern with prazosin than dry mouth, particularly when initiating therapy 3.
The dry mouth associated with prazosin is generally mild compared to medications with strong anticholinergic properties 5, 6.
If dry mouth is severe and persistent on prazosin, evaluate for other contributing medications or underlying conditions (such as Sjögren's syndrome) rather than attributing it solely to prazosin 2.