What happens when you take amitriptyline with st. john's wort?
Amitriptyline is a tricyclic antidepressant (TCA) used for major depression, neuropathic pain, migraine prevention, and sometimes insomnia. It works largely by blocking the reuptake of serotonin and norepinephrine in the brain. St. John's wort (Hypericum perforatum) is an over-the-counter herbal product marketed for low mood, and it acts on several of the same neurotransmitter systems while also affecting how the body processes many medications.
When the two are taken together, several things happen in sequence:
- St. John's wort revs up drug-clearing enzymes. It is one of the most potent herbal inducers of liver cytochrome P450 enzymes (particularly CYP3A4 and CYP2D6) and of the P-glycoprotein transporter. These are the same systems that break down and move amitriptyline.
- Amitriptyline blood levels fall. As enzyme activity ramps up over the first couple of weeks of taking the herb, the body clears amitriptyline faster, so less of the drug reaches the bloodstream at the same prescribed dose. A controlled study in patients confirmed a meaningful drop in both amitriptyline and its active metabolite.
- The antidepressant works less well. Lower blood levels can mean depression, nerve pain, or migraines start to creep back even though nothing about the dose has changed.
- Serotonin signaling is added on top. Amitriptyline blocks the serotonin transporter, and St. John's wort's constituents (such as hyperforin and hypericin) also raise serotonin tone. Stacking two serotonergic agents adds a theoretical risk of serotonin syndrome.
So the interaction is really two effects at once: a well-documented drop in drug levels, plus a mechanism-based serotonin concern.
Why is this important?
The most reliably documented problem is loss of effect. Because amitriptyline levels drift down while the herb is on board, symptoms the drug was controlling can return. A patient or clinician who does not know the herb is responsible may respond by raising the amitriptyline dose. If the herb is then stopped, enzyme activity returns to normal over the following week or two and amitriptyline levels can climb back up at the new higher dose, raising the chance of side effects such as drowsiness, dry mouth, and effects on heart rhythm.
The second concern is serotonin syndrome. Both substances raise serotonin signaling, so combining them is biologically plausible to push serotonin tone too high. It is worth noting that a documented case of serotonin syndrome from this specific pairing was not found in the literature, so this is a mechanism-based caution rather than a frequently reported event. Symptoms to recognize include agitation, confusion, sweating, shivering, fast heart rate, tremor, and muscle twitching; severe reactions involve high fever and are a medical emergency.
Finally, tricyclic antidepressants have a relatively narrow margin between a helpful level and a toxic one, so anything that moves their blood levels around unpredictably is worth taking seriously.
What should you do?
The simplest safe rule is to keep these two apart and let your prescriber guide any changes.
Before making any change: If you take amitriptyline, do not start St. John's wort on your own. If you already take both, do not stop either one abruptly. Tell your doctor or pharmacist everything you are taking and ask them to plan the transition.
Every day during the overlap or taper: Watch for signs the antidepressant may be wearing off (returning low mood, sleep problems, or pain) and for signs of serotonin syndrome (tremor, sweating, restlessness, fast heartbeat, confusion). Avoid adding other serotonin-raising agents such as tramadol, dextromethorphan, SSRIs, triptans, or MAOIs while on amitriptyline.
After St. John's wort is stopped: Enzyme activity returns to normal over roughly one to two weeks, during which amitriptyline levels can rise. Have your prescriber recheck your mood, sleep, and pain control after the herb has fully cleared, and discuss whether your amitriptyline dose needs adjusting. If you were using St. John's wort because amitriptyline alone was not helping, ask about evidence-based alternatives instead.
Which specific products are affected?
Every formulation of amitriptyline is affected, including generic amitriptyline tablets and brand-name products such as Elavil and Endep. Because this is largely a class effect of tricyclic antidepressants, closely related drugs such as nortriptyline, imipramine, desipramine, clomipramine, and doxepin carry a similar caution.
St. John's wort is sold under many product and brand names, including Kira, Perika, and Movana, as well as numerous generic store-brand extracts. It is also a frequent hidden ingredient in combination supplements marketed for mood, sleep, stress, or PMS, even when it is not named on the front of the package. Always read the full ingredient list.
The science behind it
The pharmacokinetic side of this interaction is supported by real human data. In a controlled study in patients, adding a St. John's wort extract to amitriptyline lowered the plasma levels of amitriptyline and its active metabolite, consistent with induction of the CYP enzymes and P-glycoprotein that handle the drug (Johne A et al., J Clin Psychopharmacol 2002; PMID 11799342). A broader pharmacology review summarizes the same mechanism across many drugs cleared by these enzymes, establishing St. John's wort as a clinically relevant enzyme inducer (Zhou SF et al., J Psychopharmacol 2004; PMID 15260917).
The serotonin-syndrome concern, by contrast, rests on the shared serotonergic mechanism of the two products rather than on reported cases for this specific combination, which is why it is framed here as a caution rather than an established frequent outcome.
Frequently Asked Questions
Can I take St. John's wort instead of amitriptyline if I do not like my medication?
Do not swap on your own. Stopping a prescribed antidepressant abruptly can cause discontinuation symptoms, and switching to an herbal product is a decision to make with your prescriber, who can manage the transition safely.
Does St. John's wort make amitriptyline stronger or weaker?
Weaker. By speeding up the enzymes that clear amitriptyline, it lowers the drug's blood levels, which can let symptoms return at the same dose.
What happens when I stop the St. John's wort?
Over about one to two weeks the enzymes return to normal activity and amitriptyline levels can rise again. If your dose was increased while you were on the herb, you may now be getting more drug than you need, so this is a good time to have your prescriber review the dose.
Is serotonin syndrome definitely going to happen?
No. It is a recognized theoretical risk because both raise serotonin signaling, but a documented case from this specific pair was not found. Knowing the warning signs and avoiding other serotonergic agents is a sensible precaution.
Are other tricyclic antidepressants affected the same way?
Largely yes. Related tricyclics such as nortriptyline, imipramine, and doxepin are handled by similar enzymes, so the same caution applies.
Could St. John's wort be hidden in a supplement I already take?
Yes. It is sometimes included in mood, sleep, stress, or PMS blends without being on the front label, so check the full ingredient list of anything you take.
Key takeaways
- St. John's wort speeds up the enzymes that clear amitriptyline, lowering its blood levels and reducing its effect; this drop is documented in human data.
- Both products raise serotonin signaling, adding a mechanism-based caution about serotonin syndrome, though no documented case for this specific pair was found.
- Do not start, stop, or change either one abruptly; plan any transition with your doctor or pharmacist.
- After stopping St. John's wort, amitriptyline levels can rise over one to two weeks, so have your dose rechecked.
- St. John's wort can hide in combination supplements, so always read the full ingredient label.