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Margin note · cns margin

After Prozac 40 mg, five weeks is the MAOI floor

Last reviewed · 8 min read · Updated

At least five weeks after the last fluoxetine before an MAOI meant for psychiatric disorders. Fourteen days after an MAOI before fluoxetine.

Parent half-life after chronic dosing is 4-6 days. Norfluoxetine runs 4-16 days. A 40 mg maintenance course is the setting where "perhaps longer" lives.

Dr. Elise Moreau

Peer-passed by Dr. Elise Moreau, MD - Clinical pharmacology, Bordeaux. Gather, ink, peer-pass, bind.

01 Do not borrow a two-week SSRI card

Sertraline and most other SSRIs use a two-week wait before an MAOI. Fluoxetine does not. The Prozac insert says at least five weeks after stopping, perhaps longer after chronic or high-dose treatment. Forty milligrams daily for months is both chronic and not a baby dose.

The other arrow is fourteen days after the MAOI before starting fluoxetine. Mix the arrows and you either rush serotonin syndrome or you leave someone untreated for no reason.

Linezolid and IV methylene blue are MAOI-type problems in the moment. The hospital needs the 40 mg history, not a "I stopped last Tuesday" shrug. See the leaf for the 30-day 40 mg level ranges the insert quotes.

Washout line beside a Prozac 40 mg blister

02 How to write dates that a hospitalist can use

Last 40 mg date. Last 20 mg date if you cut. Planned MAOI name. Other serotonergic drugs. Linezolid if that is in play. That is the card. "I stopped recently" is not a card.

The clock starts from the last fluoxetine of any dose unless a specialist rewrites it. A cut to 20 mg is still fluoxetine.

Five weeks toward an MAOI. Fourteen days the other way. Two weeks is the other SSRIs' gap. Do not copy a sertraline card onto Prozac.

After 30 days at 40 mg/day the insert quotes wide norfluoxetine ranges. Feeling clear is not empty.

The leaf has the numbers. This file is the switch.

03 When depression is bad and someone wants Friday anyway

Bad depression is why they want the MAOI. It is not a reason this margin can shorten five weeks. If they proceed on day 16, that is their documented risk, not a Bordeaux blessing.

Do not start a kitchen MAOI from a relative's bottle on day 20 because a forum said four weeks is enough. The insert says at least five, perhaps longer after chronic or high-dose treatment. Forty milligrams for months is that setting.

Linezolid for an infection is a same-day two-team call. Do not take the next 40 mg to stay even and do not stop silently.

IV methylene blue in a procedure is the same class of problem. Say Prozac on the anesthesia list.

Elise will not count your personal day 37.

04 When depression is bad and Friday still has to wait

Bad depression is why they want the MAOI. It is not a reason this margin can shorten five weeks. If they proceed on day 16, that is their documented risk, not a Bordeaux blessing.

Do not start a kitchen MAOI from a relative's bottle on day 20 because a forum said four weeks is enough. The insert says at least five, perhaps longer after chronic or high-dose treatment. Forty milligrams for months is that setting.

Thirty-two days is still short of 35. "Almost" is how day-32 charts get written.

A serotonin-syndrome home checklist does not empty norfluoxetine. Do not start an MAOI because you do not have clonus tonight.

If you already have rigidity, fever, or agitation on leftover fluoxetine plus another serotonergic drug, that is emergency care, not a Friday green light.

05 Norfluoxetine is why the bottle can be empty and the interaction still live

After 30 days at 40 mg/day, fluoxetine levels in the insert sit about 91-302 ng/mL and norfluoxetine about 72-258 ng/mL. Those species do not vanish on day 8. People feel "clear" because the capsule is gone. The enzyme and the serotonin risk are not clear.

Dose changes also take weeks to show fully in plasma. That is why a last-minute 40-to-20 cut does not create a short washout. The clock starts from the last fluoxetine of any dose unless a specialist says otherwise.

The activation ink is first-weeks. This file is the switch.

40 mg maintenance is the chronic/high setting the insert already flagged.
DirectionMinimum labeled wait
Fluoxetine -> psychiatric MAOI5 weeks (longer if high/chronic)
Psychiatric MAOI -> fluoxetine14 days
Other SSRIs -> MAOI (typical)2 weeks - do not copy onto Prozac
Linezolid / IV methylene blueTreat as an MAOI-type emergency conversation

06 How to count five weeks from the last fluoxetine of any dose

The clock starts from the last 40 mg or the last 20 mg if you cut. A cut is still fluoxetine. "I stopped recently" is not a card a hospitalist can use.

Five weeks toward an MAOI. Fourteen days the other way. Two weeks is the other SSRIs' gap. Do not copy a sertraline card onto Prozac.

After 30 days at 40 mg/day the insert quotes wide norfluoxetine ranges. Feeling clear is not empty. The leaf has the numbers.

Linezolid for an infection is a same-day two-team call. IV methylene blue in a procedure is the same class of problem. Say Prozac on the anesthesia list.

Elise will not count your personal day 37.

07 What not to start during the five weeks

Another SSRI on day 10 "to bridge" can still be a serotonergic pile on leftover norfluoxetine. That bridge is a specialist's, not a forum's.

Tramadol, St John's wort, and extra triptans still belong on the list during the washout. The parent is gone. The metabolite is not.

Do not use the empty bottle as proof you can donate a leftover 40 mg to a friend. The friend inherits your washout math if they start an MAOI later. Do not donate.

If the plan is not an MAOI, five weeks may not be the relevant clock. Do not apply it as a superstition to every switch. Ask which next drug.

Mail us if a sentence used two weeks for Prozac-to-MAOI. That would be a copy error.

08 Bridges that still leave norfluoxetine in the room

Another SSRI on day 10 "to bridge" can still be a serotonergic pile. That bridge is a specialist's, not a forum's.

Tramadol, St John's wort, and extra triptans still belong on the list during the washout. The parent is gone. The metabolite is not.

Do not donate a leftover 40 mg to a friend. The friend inherits your washout math if they start an MAOI later.

If the plan is not an MAOI, five weeks may not be the relevant clock. Do not apply it as a superstition to every switch. Ask which next drug.

Mail us if a sentence used two weeks for Prozac-to-MAOI. That would be a copy error. See the activation ink if the stop was about jitter, not about a switch.

09 Bring dates, not a vibe

Write the last 40 mg date on paper. Write the planned MAOI name. Write other serotonergic drugs. That is the visit. This margin will not count your personal day 37.

If someone wants to start tranylcypromine on day 16 because the depression is bad, the answer is still the five-week line plus a specialist who owns the risk, not a Bordeaux exception.

Elise files the floor. She does not start phenelzine by email.

10 Two arrows, two waits

Five weeks off 40 mg toward an MAOI. Fourteen days the other way. Reviewed 21 August 2026.

Write the last 40 mg date, any 20 mg cut, the planned MAOI name, and other serotonergic drugs. That is the card. Five weeks toward an MAOI. Fourteen days after an MAOI before fluoxetine. Two weeks is the other SSRIs' story. Do not mix those cards.

Feeling clear at day 32 is not empty. The insert allows perhaps longer after chronic or high-dose treatment. Forty milligrams for months is that setting. A home checklist does not empty norfluoxetine.

Linezolid and methylene blue are same-day calls. Do not donate leftover capsules. The leaf keeps the numbers. Mail [email protected] if we used two weeks for Prozac-to-MAOI.

A yogurt half of a 40 mg capsule is still fluoxetine. The five-week clock starts from that last messy dose. Ask for a real 20 mg if 20 mg is the plan. Other switches have other clocks. Do not copy the MAOI gap onto every next antidepressant, and do not copy a two-week sertraline card onto leftover norfluoxetine.

If you need linezolid tomorrow and you swallowed 40 mg this morning, that is a two-team call tonight. Do not take tomorrow's capsule to stay even and do not stop silently. Bring the 40 mg/day duration, not only today's swallow.

Thirty-two days is still short of five weeks. Show them the fluoxetine-specific line. Almost is how day-32 charts get written. If they wait until day 35 and the course was high and long, they may still want longer. That is the insert's perhaps-longer clause. Bring the 40 mg/day duration, not only the stop date.

Anesthesia lists should name Prozac before methylene blue. A procedure week is a two-team week. Do not treat the empty blister as a clearance for Friday. Norfluoxetine is still the long piece.

Do not donate a leftover 40 mg capsule. The friend inherits your washout math if they later start an MAOI.

Sources

  1. DailyMed Prozac 2.9 / 4.1 / 5.14: 5-week MAOI washout; 14 days after MAOI; long t½; 40 mg/day 30-day ranges.
  2. Reviewed 21 August 2026 by Dr. Elise Moreau.

Checked against the current label and reviewed by Dr. Elise Moreau. See Gather, Ink, Peer-pass, Bind.

Desk thread

Desk thread on the Prozac 40 mg washout. No personal day count from this inbox.

Chloé Martin I last took 40 mg 18 days ago. The new doctor wants phenelzine Friday.

Desk reply

Eighteen days is short of five weeks. Show them the fluoxetine-specific line, not a generic SSRI card. "Depression is bad" is why they want the MAOI. It is not a reason this margin can shorten the wait. If they still proceed, that is their documented risk. We will not bless Friday. The leaf quotes the 40 mg/day level ranges so the wait is not mysticism.

Samiya Rahman I have been off 40 mg for 32 days. Is Friday legal?

Desk reply

Thirty-two days is still short of five weeks (35 days). Show them the fluoxetine-specific line. "Almost" is how day-32 charts get written. If they wait until day 35 and your course was high and long, they may still want longer. That is the insert's perhaps-longer clause. Bring the 40 mg/day duration, not only the stop date.

Ibrahim Sow I cut from 40 to 20 two weeks ago. Does the five-week clock start from the cut?

Desk reply

The insert's washout is after stopping fluoxetine. A cut to 20 mg is still fluoxetine. Unless a specialist rewrites the clock, count from the last capsule of any strength. Two weeks at 20 mg also does not empty norfluoxetine from the 40 mg months. Do not treat the cut as a washout hack.

Rania El Idrissi I opened a 40 mg capsule and took half for two weeks. When does the five-week clock start?

Desk reply

From the last fluoxetine of any dose, including a messy half. A yogurt split is still fluoxetine. Write that last date. Do not pretend the halves were 20 mg capsules. Ask for a real 20 mg if 20 mg is the plan. The washout does not get shorter because the kitchen dose was sloppy.

Freya Nielsen I am on linezolid for an infection. I take 40 mg. What now?

Desk reply

That is a same-day call to the teams who wrote both. Linezolid is an MAOI-type interaction in the label's emergency sense. Do not start the next 40 mg to "stay even" and do not stop silently without telling them. This desk will not pick which drug yields. Bring both bottles.

Hugo Marchand I stopped 40 mg 18 days ago. Can I start phenelzine Friday if I feel empty?

Desk reply

Eighteen days is not five weeks. Feeling empty is why they want the MAOI. It is not a reason this margin can shorten the fluoxetine-specific gap. Show them the last 40 mg date. If they proceed early, that is their documented risk, not a Bordeaux blessing. Do not start a relative's leftover MAOI on day 20 because a forum said four weeks is enough.

Elena Rossi Can I start vortioxetine on day 14 after 40 mg?

Desk reply

Ask the person writing the next antidepressant. Five weeks is the MAOI line. Other switches have other clocks. Do not copy the MAOI gap onto every INN, and do not copy a two-week sertraline card onto leftover norfluoxetine. Say 40 mg and the stop date. A bridge on day 10 can still be a serotonergic pile.

Lukas Steiner Can I use a serotonin-syndrome home checklist to start earlier?

Desk reply

No. A checklist does not empty norfluoxetine. Do not start an MAOI because you do not have clonus tonight. If you already have rigidity, fever, or agitation on leftover fluoxetine plus another serotonergic drug, that is emergency care, not a Friday green light.

Piotr Szymanski I need linezolid tomorrow. I took 40 mg this morning.

Desk reply

That is a same-day two-team call, not a Bordeaux schedule. Do not take tomorrow's 40 mg to stay even and do not stop silently. They need both names tonight. This margin will not pick hold versus proceed. Bring the 40 mg/day duration, not only today's swallow.

Otto Bergmann Who underlined five weeks?

Desk reply

Elise Moreau, 21 August 2026. Mail [email protected] if a sentence used two weeks for Prozac-to-MAOI. That would be a copy error from another SSRI.