Drug interactions
Fluoxetine + Lisdexamfetamine
Severity: Major
Fluoxetine and Lisdexamfetamine: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Both drugs increase serotonergic activity, and fluoxetine also inhibits CYP2D6, which may raise amphetamine exposure. The combination can cause serotonin syndrome with agitation, tremor, hyperthermia and autonomic instability.
What this interaction means in plain words
Fluoxetine and Lisdexamfetamine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Fluoxetine belongs to Central Nervous System; Lisdexamfetamine belongs to Central Nervous System.
Why it happens
Additive serotonergic effects, plus CYP2D6 inhibition by fluoxetine reducing amphetamine clearance.
What to do
Start lisdexamfetamine at a low dose and titrate slowly, monitoring for serotonin syndrome, especially after dose increases. Stop both serotonergic agents and give supportive care if symptoms appear.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
Other interactions of Lisdexamfetamine
- Isocarboxazid + Lisdexamfetamine Contraindicated
- Linezolid + Lisdexamfetamine Contraindicated
- Lisdexamfetamine + Phenelzine Contraindicated
- Lisdexamfetamine + Procarbazine Contraindicated
- Lisdexamfetamine + Rasagiline Contraindicated
- Lisdexamfetamine + Safinamide Contraindicated
Frequently asked questions
Can I take Fluoxetine with Lisdexamfetamine?
MediHelp rates the interaction as major. Fluoxetine and Lisdexamfetamine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs increase serotonergic activity, and fluoxetine also inhibits CYP2D6, which may raise amphetamine exposure. The combination can cause serotonin syndrome with agitation, tremor, hyperthermia and autonomic instability.
How serious is the interaction between Fluoxetine and Lisdexamfetamine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Start lisdexamfetamine at a low dose and titrate slowly, monitoring for serotonin syndrome, especially after dose increases. Stop both serotonergic agents and give supportive care if symptoms appear.
What other medicines interact with Fluoxetine?
MediHelp also lists interactions of Fluoxetine with, for example, Isocarboxazid, Mavacamten, Methylene blue. The full list is on the Fluoxetine page.
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