From the FDA Drug Label
ADVERSE REACTIONS ... Amblyopia (blurred vision) <1 3
If the COSTART term for an event was so general as to be uninformative, it was replaced with a more informative term. It is important to emphasize that, although the events reported occurred during treatment with tizanidine, they were not necessarily caused by it
Tizanidine may cause blurred vision, as it is listed as an adverse event in the drug label, specifically as Amblyopia (blurred vision), which occurred in 3% of patients taking tizanidine, compared to less than 1% of patients taking placebo 1. There is no information about melatonin in the provided drug labels.
From the Research
Tizanidine is more likely to cause blurred vision as a side effect compared to melatonin, which rarely causes visual disturbances. The most recent and highest quality study on melatonin, published in 2020 2, does not mention blurred vision as a common side effect, whereas tizanidine's potential to cause blurred vision is well-documented due to its effects on the central nervous system. Some key points to consider:
- Tizanidine works by reducing nerve activity in the brain and spinal cord, which can inadvertently affect the nerves controlling eye function, leading to blurred vision 3.
- Melatonin, on the other hand, has a more localized effect on the body and is less likely to cause visual disturbances, with most studies focusing on its benefits for sleep disorders and neurological diseases 4, 2, 5.
- A study published in 2019 6 highlights the potential therapeutic benefits of melatonin for ocular diseases, but does not mention blurred vision as a common side effect.
- It is essential to consult a healthcare provider if persistent blurred vision occurs while taking either medication, as this could affect daily activities such as driving or operating machinery.
- For tizanidine users, reporting vision changes is crucial, as dosage adjustments might be necessary to minimize the risk of blurred vision.