What happens when you take cyclosporine with st. john's wort?
Cyclosporine is a calcineurin inhibitor used to prevent rejection in organ transplant recipients and to treat severe autoimmune conditions like psoriasis and rheumatoid arthritis. It has a narrow therapeutic window, meaning the difference between a level that prevents rejection and one that causes toxicity or fails to work is small. The drug is broken down by an enzyme in the liver and small intestine called CYP3A4, and it is also pumped out of cells by a transporter called P-glycoprotein.
St. John's wort, an herbal product widely sold for low mood, contains a constituent called hyperforin that strongly activates the pregnane X receptor (PXR). Activation of PXR ramps up production of CYP3A4 and P-glycoprotein. Within one to two weeks of starting St. John's wort, the body becomes far more efficient at clearing cyclosporine. Blood concentrations fall sharply, and the immunosuppressive effect collapses.
Pharmacokinetic studies in renal transplant patients have shown that two weeks of St. John's wort coadministration reduces the dose-corrected area under the curve, peak concentration, and trough concentration of cyclosporine by approximately 46%, 42%, and 41%, respectively. These numbers are not subtle laboratory shifts; they are the difference between protected and unprotected.
Why is this important?
This is one of the best-documented and most dangerous herb-drug interactions ever described. In a 2000 Lancet report, two heart transplant recipients developed acute rejection after starting St. John's wort for low mood. Their cyclosporine concentrations dropped to subtherapeutic levels, and rejection began within weeks. Once the herb was stopped, cyclosporine levels recovered, but at least one patient required treatment for the rejection episode.
Subsequent case reports have described the same sequence in kidney and liver transplant recipients. A kidney transplant patient taking St. John's wort for several weeks needed her cyclosporine dose escalated dramatically to reach therapeutic levels; when the herb was discontinued, her requirement returned to baseline, confirming the herb was the cause.
The stakes are unusually high here. Acute rejection can damage the graft permanently, require intensive treatment with high-dose steroids and anti-thymocyte globulin, and in some cases lead to graft loss. Beyond transplant patients, anyone using cyclosporine for autoimmune disease may experience disease flares if the medication stops working.
The interaction is also slow to resolve. Because St. John's wort works by inducing new enzyme production, the elevated CYP3A4 activity persists for one to two weeks after the herb is stopped while the extra enzymes are degraded. During that window, cyclosporine doses may need to be temporarily raised, then carefully tapered back as enzyme levels normalize.
What should you do?
If you take cyclosporine, do not take St. John's wort. This applies to capsules, tinctures, teas, and combination herbal products labeled for mood, sleep, or stress. Read labels carefully on multi-ingredient supplements, especially those marketed for emotional wellness or menopause, since St. John's wort is often blended with other herbs.
If you have been taking St. John's wort and are now starting cyclosporine, tell your transplant team or prescribing physician before your first dose. They will likely delay starting the herb's washout, monitor trough levels frequently in the first month, and adjust the cyclosporine dose as enzyme activity returns to baseline.
If you are already on cyclosporine and realize you have been taking St. John's wort, stop the herb immediately and call your transplant coordinator or prescriber the same day. Do not wait for the next routine appointment. You will likely need an extra trough level check within a few days, and possibly a temporary dose increase followed by careful tapering once enzyme induction wears off.
For mood symptoms, ask your physician about evidence-based alternatives that do not interact with cyclosporine. Several SSRIs and other antidepressants are compatible with calcineurin inhibitors when chosen carefully, though some also affect CYP3A4 and must be selected with prescriber input.
Which specific products are affected?
The interaction applies to all branded and generic cyclosporine products, including Sandimmune, Neoral, Gengraf, and the ophthalmic formulation Restasis when used systemically at immunosuppressive doses. Topical and ophthalmic preparations with minimal systemic absorption are less of a concern but should still be discussed with a clinician.
On the herb side, the interaction occurs with any hypericum perforatum extract regardless of brand. Standardized products marketed by hyperforin or hypericin content (often 0.3% hypericin) are particularly potent inducers. Lower-hyperforin extracts may have less effect, but no product can be considered safe in transplant recipients given the severity of the consequences.
Be cautious of multi-herb formulas marketed for depression, anxiety, sleep, or menopause; St. John's wort is a common ingredient and may not be highlighted on the front of the label. Loose tea blends and homeopathic-style tinctures can also contain enough hypericum to cause clinically meaningful induction.
The bottom line
St. John's wort and cyclosporine are an absolute contraindication for transplant recipients. The combination has caused acute organ rejection in published case reports and produces a roughly 40-50% drop in cyclosporine exposure. If you are on cyclosporine for any reason, do not take St. John's wort, and tell your prescriber immediately if you have. The herb's effect lingers for one to two weeks after stopping, so close blood level monitoring is essential during that window.