Five-week fluoxetine washout before an MAOI

01Five weeks is the fluoxetine-to-MAOI clock

At least five weeks must pass after stopping PROZAC before a psychiatric MAOI starts. That is contraindication language, not a polite suggestion. The reverse gap - off an MAOI, onto fluoxetine - is at least fourteen days.

Forum posts that say 'just start the new one Monday' treat fluoxetine like sertraline. It is not. Parent drug after chronic use hangs around four to six days. The metabolite hangs longer. Plasma will not tell the whole story for several weeks after a dose change.

Serotonin syndrome is the named risk: agitation, clonus, fever, autonomic chaos. It can happen with MAOIs, and it can happen when other serotonergic drugs stack. This despatch is a switch calendar. It is not a home protocol for phenelzine.

02The serotonergic pile during a messy gap

Triptans, tramadol, lithium, fentanyl, methadone, buspirone, amphetamines, and St. John's wort sit on the PI's serotonin-syndrome list. A washout week is a bad time to add any of them 'for the headache of coming off.'

Tryptophan supplements from a health shop count. So does a leftover tramadol from a dental visit. Write them on the same card as the last 20 mg date.

If fever, clonus, or autonomic chaos appears in the gap, that is emergency language, not a 'discontinuation zap.' Say fluoxetine and the other agent at the door.

This desk will not invent a safe stack. The contraindication text is already long enough.

03CYP2D6 hangover after the last 20 mg swallow

Fluoxetine can leave a person looking like a CYP2D6 poor metabolizer for weeks after the last capsule. Narrow-index substrates started in that window belong at the low end of their ranges until the prescriber says otherwise.

TCAs, some antipsychotics, and antiarrhythmics such as flecainide or propafenone sit on that caution. A 'clean' psychiatry switch that ignores a flecainide script is not clean.

Write the last-capsule date on the cardiology list as well as the psychiatry list. Five weeks is a shared calendar, not a specialty secret.

04Linezolid and methylene blue use the same MAOI logic

Starting PROZAC in a person on linezolid or intravenous methylene blue is contraindicated. If an MAOI of that kind must start while someone is already on fluoxetine, the PI says discontinue fluoxetine first.

Methylene blue by other routes (oral tablets, local injection) is carved out in the 'no reports' sentence. Do not treat that carve-out as permission to stack. Flag the dye and the antibiotic on the reconciliation form.

Infectious-disease and perioperative teams miss psychiatry lists. The person who knows the 20 mg capsule is on the nightstand has to say it out loud before a methylene-blue plan proceeds.

05Monday-start mail that skips the metabolite

Readers forward screenshots that treat all SSRIs as interchangeable washouts. Fluoxetine is the long one. If a clinic used a shorter gap, that is their documented exception, not a letters-desk default.

Imported 'Prozac' blisters with no lot you can verify are a quality problem on top of a calendar problem. This desk does not bless leftover capsules from a traveler.

Nora Lindqvist will not invent a three-week 'Nordic compromise.' The US PI says five weeks to a psychiatric MAOI. That is the line we annotate.

06What to write on a paper switch calendar

Last Prozac 20 mg date. Planned first dose of the next agent. Whether that agent is an MAOI, a different SSRI, or something else. Any linezolid or dye exposure. The CYP2D6 list. One card, one ink color, no phone notes that vanish.

If the next drug is not an MAOI, the five-week rule may not apply, but the long tail still changes how you read early side effects. Residual fluoxetine can look like the new drug 'already failed' in week one.

Cross-check activation symptoms on the activation despatch so a washout week is not mistaken for a new-drug activation week.

Keep the serotonergic pile visible

• Serotonergic stack examples on the PI: triptans, TCAs, fentanyl, lithium, tramadol, tryptophan, meperidine, methadone, buspirone, amphetamines, St. John's wort
• Do not add those during a messy switch without the prescriber
• Mail [email protected] only for editorial questions about this despatch

07Thioridazine still waits five weeks for a different reason

Thioridazine is contraindicated with PROZAC and for a minimum of five weeks after fluoxetine stops. The mechanism here is CYP2D6 inhibition plus QT, not serotonin syndrome. Pimozide is also contraindicated.

Fluoxetine can make a normal CYP2D6 metabolizer look like a poor metabolizer. Narrow-index CYP2D6 substrates started during fluoxetine, or in the five weeks after, belong at the low end of their ranges.

A switch letter that only mentions MAOIs and forgets thioridazine is an incomplete chart note. Psychiatry and cardiology both own that line.

08Fourteen days when the MAOI is the drug you are leaving

People remember the five-week number and forget the other arrow. Starting 20 mg capsules inside two weeks of a psychiatric MAOI is also contraindicated. Write both dates on one card: last MAOI swallow, first fluoxetine swallow.

A 'washout weekend' after phenelzine or tranylcypromine is not fourteen days. If someone already started the capsule early, that is a clinical emergency conversation, not a dose-skip to catch up.

Other antidepressants have their own gaps. Do not copy fluoxetine's five weeks onto every SSRI, and do not shrink fluoxetine to another drug's shorter clock.

09The first week on the next agent still carries fluoxetine

Early nausea or jitter on the incoming drug may be leftover parent and metabolite. Do not raise the new milligram on day four because the old capsule 'should be gone.'

If the incoming agent is not an MAOI, the five-week hard stop may not apply, but the long tail still muddies the read. Keep a two-line scrap across the gap so two drugs do not get blamed for one leftover.

Borrowed fluoxetine taken 'just in case' during the gap resets the MAOI clock. Say that in the room before anyone draws a new start date.

10Print both arrows before anyone names a Monday start

Five weeks off fluoxetine before a psychiatric MAOI. Fourteen days off a psychiatric MAOI before 20 mg capsules. People remember one arrow and break the other. Print both on the same card with last-swallow dates.

A clinic that used a shorter gap should document why. This despatch will not adopt that exception as a letters default. Serotonin syndrome is the named reason the US PI keeps the longer wait.

If the incoming drug is a different SSRI, ask the prescriber for that drug's own gap. Do not copy fluoxetine's five weeks onto every switch, and do not shrink fluoxetine to sertraline's habit.

Thioridazine and pimozide remain separate hard stops. A psychiatry-only card that forgets QT is still incomplete after the MAOI line is perfect.

Cirrhosis slows fluoxetine and norfluoxetine clearance. A lower or less frequent dose is the labeled caution there. A washout after cirrhosis is not a shorter calendar; if anything the tail is longer. Ask hepatology and psychiatry to share the last-capsule date.

Nursing data report fluoxetine and norfluoxetine in milk, with infant agitation and poor weight gain in published cases. A switch calendar that ignores lactation is incomplete. That conversation belongs with the prescriber and a lactation clinician, not with a forum restart date.

11Why norfluoxetine outlasts the last 20 mg capsule

Fluoxetine demethylates in the liver to norfluoxetine. In animal models the S-metabolite inhibits serotonin uptake about as hard as the parent. That is why a 'last Friday capsule' is not a clean slate by the next clinic slot.

After thirty days at 40 mg daily, published ranges put fluoxetine somewhere near 91 to 302 ng/mL and norfluoxetine near 72 to 258 ng/mL. Those figures are not a home assay. They are a reminder that chronic use accumulates.

UK SmPC language is blunt: persistence for five to six weeks after discontinuation. Stockholm letters use that as a teaching span, then still defer to the US five-week MAOI rule when an MAOI is the next drug.

12Seal on the washout strip

Print the last-capsule date before anyone names an MAOI. Fourteen days the other way. Linezolid and IV methylene blue count. Thioridazine waits five weeks for QT.

Open the fluoxetine letter for the rest of the interaction table. This postscript is only the switch clock.

Poor CYP2D6 metabolizers already handle S-fluoxetine slowly. Adding a five-week hangover on top is why narrow-index lists must travel with the last-capsule date. Do not leave flecainide or a TCA off the card because 'this is a psychiatry switch.'

Borrowed capsules during the gap reset the clock and the quality problem. Say that before anyone inks a new Monday. Keep one paper card, one ink color, no vanishing phone notes.