From the Guidelines
Melatonin supplements are not typically associated with significant anticholinergic side effects, according to the most recent and reliable evidence. The American Academy of Sleep Medicine clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders, updated in 2015 1, notes that melatonin is generally considered safe, with few reported serious adverse effects. While melatonin can cause various side effects such as headaches, somnolence, and gastrointestinal upset, anticholinergic effects like dry mouth, blurred vision, constipation, and urinary retention are not commonly reported.
Some key points to consider when evaluating the potential for anticholinergic side effects from melatonin include:
- The dose of melatonin: Higher doses, typically above 10 mg, may increase the risk of adverse effects, although anticholinergic effects are not specifically highlighted as a concern at these doses 1.
- Individual susceptibility: People with certain preexisting conditions or those taking other medications may be more prone to experiencing side effects from melatonin, including potentially anticholinergic effects, though this is not a primary concern based on the available evidence 1.
- The formulation of melatonin: The purity and reliability of melatonin preparations can vary, with United States Pharmacopeial Convention Verified formulations considered most reliable 1.
Given the current evidence, the risk of significant anticholinergic side effects from melatonin supplements appears to be low, especially when used at typical doses and in the absence of specific predisposing factors. However, as with any supplement or medication, it is essential to be aware of potential side effects and to consult with a healthcare provider if concerns arise, particularly for individuals with conditions that could be exacerbated by anticholinergic effects, such as glaucoma or enlarged prostate.
From the Research
Melatonin and Anticholinergic Side Effects
- There is no direct evidence in the provided studies to suggest that melatonin supplements have anticholinergic side effects 2, 3, 4, 5.
- Tri-cyclic antidepressants, which are sometimes used to treat insomnia, have been known to have unwanted anticholinergic side effects, but low-dose doxepin has been shown to be free of these effects at certain doses 2.
- Melatonin has been explored as a hypnotic and has been shown to have a positive effect on sleep regulation, with little to no reported side effects 2, 3, 4.
- The safety and efficacy of melatonin for sleep disorders have been studied, and while it has been found to be generally well-tolerated, its effects on various physiological systems and potential interactions with other medications are still being researched 4, 5.
Melatonin's Effects on the Body
- Melatonin is a hormone that plays a key role in regulating the circadian rhythm and has been shown to have antioxidant, anti-inflammatory, and neuroprotective effects 3, 5.
- The primary physiological function of melatonin is to convey information about the daily cycle of light and darkness to the body, which helps to organize various physiological functions, including sleep-wake rhythms, immune function, and glucose regulation 5.
- Melatonin has been found to have a positive effect on sleep onset, duration, and quality, and has been used to treat various sleep disorders, including insomnia, sleep-related breathing disorders, and circadian rhythm sleep-wake disorders 3, 4.