Serious adverse reactions are rare when applied topically, but may occur in connection with absolute overdose or ingestion. The symptoms consistent with taking a very large overdose are; the excitation of the central nervous system causing restlessness, excitement, nervousness, dizziness, tinnitus, blurred vision, nausea and vomiting, muscle twitching, tremors and convulsion. In the event any of these symptoms appear, seek medical attention immediately.