Choice A reason: Hard candy can be used for a dry mouth, which is a common side effect of St. John's wort. Choice B reason: Another form of contraception is needed, because St. John's wort can reduce the effectiveness of oral contraceptives and increase the risk of unplanned pregnancy. This information requires further instruction from the nurse. Choice C reason: Insomnia may occur while taking the medication, which is another possible side effect of St. John's wort. The client should be advised to take the medication in the morning or afternoon, and avoid caffeine and alcohol. Choice D reason: Sensitivity to the sun can develop, which is a rare but serious side effect of St. John's wort. The client should be instructed to wear sunscreen and protective clothing when exposed to sunlight.