All medications

Fluoxetine

Mental health

Also known as Prozac

Fluoxetine is an SSRI, a type of antidepressant that raises the level of serotonin, a chemical messenger your brain uses to regulate mood. The honest truth about SSRIs: they take two to six weeks to work, and side effects often show up before the benefits. Fluoxetine also stays in your body longer than most antidepressants, which means missing an occasional dose is less of a crisis — but it's still not something to stop on your own.

How to take it

When

Usually once a day in the morning — it can be energizing and keep you up if taken late.

Food

With or without food. If it upsets your stomach, take it with a meal.

Avoid

St. John's wort and other serotonin-boosting products. Check before mixing with ibuprofen or naproxen — SSRIs can raise bleeding risk.

Good to know

Antidepressants can rarely cause new or worsening depression or suicidal thoughts, especially in people under 25. If your mood gets darker, tell someone and call your doctor right away.

Missed a dose?

Take it as soon as you remember. If it's close to your next dose, skip the missed one and get back on schedule. Never take two doses to make up for one.

Common side effects

  • Nausea, especially in the first couple of weeks — it usually fades
  • Trouble sleeping or feeling jittery
  • Headache
  • Less appetite than usual
  • Sexual side effects, like lower desire or trouble finishing — common, and worth telling your doctor about

Call a doctor if

Educational only. This summary is drawn from public FDA labeling and MedlinePlus and simplified for readability. Your prescription label and your pharmacist always come first — doses and instructions vary from person to person.