A client diagnosed with psoriasis is prescribed coal tar. Which statement indicates the client needs further instruction?

The statement that indicates the client needs further instruction is about the potential for systemic effects from coal tar. Coal tar is primarily used topically for conditions like psoriasis, and it is applied directly to the affected area. While it can have some local side effects such as irritation, the likelihood of systemic absorption leading to significant systemic reactions is low. Therefore, understanding that systemic effects are not a common or expected outcome from properly used coal tar therapy is crucial for safety and efficacy.

In contrast, the other statements are accurate and reflect important client education points. Phototoxicity is a known risk when using coal tar, especially if the client is exposed to sunlight, so awareness of this is essential for preventing skin damage. The unpleasant odor of coal tar is a common side effect that clients may experience, and it's important to set realistic expectations about the treatment. Additionally, the potential for staining skin and hair is another accurate reflection of coal tar's properties, and educating clients on how to manage this issue can improve acceptance of the treatment.