Which side effect is NOT associated with Synthroid?

The correct answer is based on the side effects typically associated with Synthroid, which is a brand name for levothyroxine, a synthetic form of the thyroid hormone used to treat hypothyroidism. Common side effects of Synthroid include insomnia, tremors, and palpitations, all of which can result from the medication increasing metabolism and affecting the cardiovascular system due to elevated thyroid hormone levels.

Vomiting is not commonly recognized as a side effect of Synthroid. While gastrointestinal upset can occur with many medications, vomiting in particular is not a typical or expected side effect associated with levothyroxine. This distinction highlights the importance of understanding each medication's profile and its common reactions within the context of hormone replacement therapy for thyroid deficiencies.