Zopiclone and Bitter Taste
Yes, zopiclone commonly causes bitter taste as a side effect, with studies showing it occurs in approximately 7-26% of patients taking the medication. 1
Evidence for Bitter/Metallic Taste with Zopiclone
- Multiple clinical studies have consistently identified unpleasant taste (described as bitter or metallic) as one of the most common adverse effects of zopiclone 1
- In studies examining eszopiclone (the S-isomer of zopiclone), five studies found a +0.07 risk difference for unpleasant taste compared to placebo 1
- Individual studies report even higher rates of taste disturbance:
- Krystal and colleagues reported unpleasant taste in 26.1% of eszopiclone patients versus 5.6% with placebo 1
- Walsh reported significantly greater frequency of unpleasant taste (19.7% versus 1.1%) 1
- Soares and colleagues found a significant increase in unpleasant taste with eszopiclone (17.6% versus 0.5%) 1
- Joffe and colleagues reported a 15.2% risk for metallic taste 1
Characteristics of the Taste Side Effect
- The taste disturbance is typically described as "bitter" or "metallic" 2, 3
- It is usually the most commonly reported adverse event in clinical trials and post-marketing studies 3, 4
- In the largest available post-marketing study, bitter aftertaste was reported in 3.6% of patients 4
- The taste disturbance appears to be dose-related, with higher incidence at higher doses 1
Clinical Significance
- Despite the bitter taste side effect, zopiclone is generally well tolerated by patients of all ages 2, 3
- The American Academy of Sleep Medicine clinical practice guidelines note that unpleasant taste is the only consistent adverse event occurring in excess of placebo with eszopiclone 1
- Treatment withdrawal due to this adverse effect is seldom required 2, 3
- The benefits of zopiclone in treating insomnia are generally considered to outweigh the harms, including the bitter taste side effect 1
Management of Taste Disturbance
- The taste disturbance is typically transient and resolves after discontinuation of the medication 2, 4
- Taking the medication immediately before sleep may reduce awareness of the taste disturbance 3
- Patients should be informed about this common side effect before starting treatment to improve adherence 2, 3
This taste disturbance, while bothersome to some patients, is generally not considered a serious adverse effect that would preclude the use of zopiclone in appropriate patients with insomnia 1, 3.