Salicylic acid is prescribed for psoriasis. Which symptom indicates systemic toxicity from this medication?

Salicylic acid, particularly when used in higher doses or improperly, can lead to systemic toxicity. One classic symptom of this toxicity is tinnitus, which is often described as a ringing or buzzing noise in the ears. This symptom arises due to the drug's effects on the central nervous system and is a known sign of salicylate toxicity.

Understanding why tinnitus indicates systemic toxicity is vital for recognizing potential adverse effects in patients undergoing treatment with salicylic acid. Additionally, while other symptoms like diarrhea, constipation, and decreased respirations can be associated with various medical conditions or other drug effects, they are not specific indicators of systemic toxicity from salicylic acid. Thus, tinnitus serves as a direct warning sign that the concentration of salicylic acid in the body may be reaching harmful levels.