HPPD may refer to:

• Hallucinogen persisting perception disorder, a perception disorder that can be caused by hallucinogenic drug use
• 4-hydroxyphenylpyruvate dioxygenase, an enzyme found in almost all aerobic life forms and the primary target of some herbicides

• One of those HPPD inhibitor herbicides, a 4-hydroxyphenylpyruvate dioxygenase inhibitor

• Hours per patient-day, a staffing goal to determine the number of clinicians needed to provide a certain standard of care to a set of patients

This disambiguation page lists articles associated with the title HPPD.
If an internal link led you here, you may wish to change the link to point directly to the intended article.