Fluoxetine dosage: what you need to know

Fluoxetine is one of the most prescribed SSRIs for depression, anxiety, OCD and a few other conditions. Getting the dose right can boost the benefits and keep side effects in check. Below is a quick, no‑fluff rundown of the typical doses, how doctors decide on them, and what you should do if you need to tweak your schedule.

Standard adult dosing

For most adults, treatment starts at 20 mg once daily. Doctors usually pick a morning dose because fluoxetine can be a bit activating. If symptoms aren’t improving after a couple of weeks, the dose may be lifted to 40 mg. The medication comes in 10 mg, 20 mg and 40 mg tablets, so a 40‑mg increase often means adding another 20‑mg pill.

The ceiling for most indications is 80 mg per day. Anything above that rarely adds extra benefit and just raises the risk of nausea, insomnia or anxiety. Some people stay on the 20‑mg dose forever if it works; others need the full 60‑80 mg range, especially for OCD or severe depression.

Special populations & adjustments

Teens (ages 12‑17) with OCD typically start at 10 mg and can be titrated up to 40 mg. For depression in adolescents, many clinicians begin at 20 mg, but they watch closely for any increase in suicidal thoughts.

Elderly patients often need a lower start, like 10 mg, because the liver processes fluoxetine more slowly. If you have liver disease, kidney problems, or are on other meds that affect the CYP450 system, your doctor may keep you at the lowest effective dose.

Switching from another SSRI or a tricyclic antidepressant usually involves a brief overlap (the “wash‑out” period). Fluoxetine’s long half‑life (about 4‑6 days) can actually simplify the switch, but you still need a doctor’s plan to avoid serotonin syndrome.

Missed a dose? Take it as soon as you remember, unless it’s almost time for the next scheduled tablet. In that case, just skip the missed one—don’t double up.

Taking fluoxetine with food isn’t required, but a light snack can reduce stomach upset. Consistency matters: try to take it at the same time each day, preferably in the morning, to keep blood levels steady.

Finally, never change your dose without talking to a healthcare professional. Even a small jump can shift how you feel, and stopping abruptly can cause withdrawal symptoms like dizziness or mood swings.

Bottom line: start low, go slow, and keep an eye on how you feel. With the right dose, fluoxetine can be a powerful tool for getting your mood back on track.