A drug holiday (sometimes also called a drug vacation, medication vacation, structured treatment interruption, tolerance break, treatment break or strategic treatment interruption) is when a patient stops taking a medication(s) for a period of time; anywhere from a few days to many months or even years if the doctor or medical provider feel it is in the patient's best interests. It is important not to discontinue any medication without the close supervision of the prescribing party.

Planned drug holidays are used in numerous fields of medicine. They are perhaps best known in HIV therapy, after a study showed that stopping medication may stimulate the immune system to attack the virus. Another reason for drug holidays is to permit a drug to regain effectiveness after a period of continuous use, and to reduce the tolerance effect that may require increased dosages.

In addition to drug holidays that are intended for therapeutic effect, they are sometimes used to reduce drug side effects so that patients may enjoy a more normal life for a period of time such as a weekend or holiday, or engage in a particular activity. For example, it is common for patients using SSRI anti-depressant therapies to take a drug holiday to reduce or avoid side effects associated with sexual dysfunction.

In the treatment of mental illness, a drug holiday may be part of a progression toward treatment cessation. The holiday is also a tool to assess a drug's benefits against unwanted side effects, assuming that both will dissipate after an extended vacation.