What is a common side effect of psychoactive substances?

Blurred vision is a common side effect associated with many psychoactive substances. These substances can affect the central nervous system and alter the normal functioning of the visual pathways. This disruption can result in visual disturbances such as blurred vision, which may occur due to various factors, including the impact of the substance on neurotransmitter activity, changes in blood pressure, or effects on the eye muscles.

In contrast, enhanced clarity of thought, increased energy without side effects, and long-term memory improvement are not typical side effects of psychoactive substances. These options may imply beneficial cognitive enhancements, which are misleading in the context of most psychoactive substances, as they often impair cognitive functions rather than enhance them. This highlights the importance of understanding the potential negative consequences of psychoactive substance use, particularly the unexpected and often harmful side effects that can arise.