Levomethamphetamine (other names include l-methamphetamine, levodesoxyephedrine, l-desoxyephedrine, levmetamfetamine), is the levorotary (R-enantiomer) of methamphetamine. Levomethamphetamine is a sympathomimetic vasoconstrictor which is the active ingredient used in some over-the-counter nasal decongestants including Vicks Vapor Inhaler.

Levomethamphetamine affects the sympathetic nervous system but has little activity in the central nervous system, so it is not thought to possess an addiction potential anywhere near that of racemic methamphetamine or dextromethamphetamine. Among its few physiological effects are the vasoconstriction that makes it useful for nasal decongestion. The elimination half life of levomethamphetamine is between 13.3 and 15 hours.

When used as a nasal decongestant, levomethamphetamine has potential side effects resembling those of other sympathomimetic drugs used for the same purpose; these effects include hypertension (elevated blood pressure), tachycardia (rapid heart rate), nausea, stomach cramps, dizziness, headache, and tremors.^{[citation needed]}