A client experiences residual effects following an acute attack of Meniere's disease and receives a new prescription for an antihistamine. Which assessment finding indicates that the medication is effective?

Choice A reason: Meniere’s disease is characterized by vertigo, tinnitus, and hearing loss due to inner ear dysfunction. Antihistamines are prescribed to reduce vertigo and improve balance. The ability to ambulate easily without vertigo indicates that the medication is effective in controlling the primary symptom of Meniere’s disease. This finding directly reflects therapeutic benefit. Choice B reason: A blood pressure of 120/80 mm Hg is normal but unrelated to the effectiveness of antihistamines in treating Meniere’s disease. Antihistamines do not primarily affect blood pressure, so this finding does not demonstrate medication effectiveness. Choice C reason: A headache pain rating of 0 is positive but not directly related to Meniere’s disease or antihistamine therapy. Headaches are not a primary symptom of Meniere’s disease, so this finding does not indicate effectiveness of treatment. Choice D reason: An oxygen saturation of 99% on room air is normal but unrelated to Meniere’s disease or antihistamine therapy. Oxygenation status is not affected by antihistamines in this context, so this finding does not demonstrate effectiveness of treatment.