A client has a new order to take guaifenesin (Mucinex) every 4 hours as needed. The nurse giving medication instructions to the client tells the client to be sure to:

A. Take an extra dose if the cough is accompanied by fever: Increasing the dosage without medical direction is unsafe and could lead to overdose or side effects. A fever with a cough may indicate infection and should prompt medical evaluation, not increased self-dosing. B. Take the tablet with a full glass of water: Guaifenesin is an expectorant that helps loosen mucus in the airways. Taking it with a full glass of water enhances its effectiveness by promoting hydration, which is essential for thinning and mobilizing secretions. C. Crush the sustained-release tablet if immediate relief is needed: Sustained-release tablets should never be crushed, as this destroys the time-release mechanism and can lead to rapid drug release and toxicity. D. Be aware of irritability as a side effect: Irritability is not a common or expected side effect of guaifenesin. More typical side effects include nausea, vomiting, or dizziness. This instruction is misleading and not relevant for patient education.