Final answer:
The client shows an understanding of Phenytoin instructions by stating they will use a soft toothbrush, which is important to prevent gum overgrowth, a possible side effect of the medication. Other options indicate misunderstandings about how to manage missed doses and possible side effects.
Step-by-step explanation:
The correct statement made by the client that indicates an understanding of the instructions regarding their prescribed medication, Phenytoin 100 mg to be taken orally 3 times daily, would be: "I will use a soft toothbrush to brush my teeth." This understanding is important because Phenytoin can cause gum overgrowth (gingival hyperplasia), making oral care crucial to prevent gum disease.
It is not okay to break capsules unless specified by a healthcare provider, as this can alter drug release and efficacy. If a dose is missed, the patient should take it as soon as remembered unless it is close to the time for the next dose, to maintain therapeutic levels of the medication. A sore throat is not a normal side effect of Phenytoin and could indicate a more serious condition like an infection or an adverse drug reaction requiring medical attention.