Which is a common side effect of opioids?

• A. Dizziness
• B. Euphoria
• C. Nausea
• D. Insomnia

Answer: (C)

Opioids commonly cause nausea because they stimulate the chemoreceptor trigger zone in the brainstem and slow gastric emptying. This combination leads to nausea early in treatment or after dose increases, making it a frequent adverse effect. Dizziness can occur from CNS depression or orthostatic changes, but it’s less consistently reported than nausea. Euphoria can happen with some opioids, especially in susceptible individuals, but it’s not universal and relates more to abuse potential than a predictable side effect. Insomnia is not typical because opioids tend to cause sedation rather than wakefulness. Remember, constipation is another frequent opioid side effect due to slowed gut motility, though it isn’t listed here.