Bacopa monnieri may interact with certain medications, including those commonly used for neurodegenerative and psychiatric conditions, although research in this area is limited. Because Bacopa monnieri may affect the serotonin, dopamine, and cholinergic systems, it is possible it could interact with pharmaceuticals that act on these systems. This includes anticholinergic medications, like those used to treat glaucoma and Alzheimer’s disease. Additionally, an in vitro study found that Bacopa monnieri inhibited the activity of certain cytochrome P450 enzymes (e.g., CYP3A4, CYP2C9, CYP2C19) and could therefore cause significant adverse reactions when taken alongside drugs that are metabolized by these enzymes, like clozapine, haloperidol, fluoxetine, and phenytoin.[1] In a case study, a patient taking cevimeline (a cholinergic agonist that stimulates saliva production and is metabolized by P450 enzymes) experienced malaise, nausea, and tachycardia after taking a supplement containing Bacopa monnieri. The clinicians suspected cholinergic toxicity due to the herb-drug interaction. Symptoms resolved once the supplement was discontinued.[2]
There is also rat research that found Bacopa could substantially increase thyroxine levels (T4), meaning it could interact with thyroid medications.[3] Other possible interactions that have not yet been documented could also exist. This is why it is very important to speak with a clinician before taking Bacopa monnieri, especially when it will be used in combination with prescription medications.