Which agent should be avoided or used with great caution in a patient who actively uses methamphetamine?

Methamphetamine is a sympathomimetic; combining it with epinephrine risks dangerous additive cardiovascular effects (severe hypertension, arrhythmia). Avoid or minimize vasoconstrictors in active users.Other options: Plain lidocaine, acetaminophen, and fluoride do not carry this sympathomimetic interaction risk.Key exam takeaway: Avoid/limit epinephrine in active methamphetamine (and cocaine) users to prevent cardiovascular crises.