Can Vyvanse (lisdexamfetamine) be taken with Japanese knotweed and milk thistle?

Can Vyvanse Be Taken with Japanese Knotweed and Milk Thistle?

Yes, Vyvanse (lisdexamfetamine) can be taken with both Japanese knotweed and milk thistle, but Japanese knotweed should be discontinued 2 weeks before any surgical procedure, and milk thistle has minimal interaction potential with most medications including stimulants.

Japanese Knotweed (Hu Zhang)

Perioperative Considerations

• The Society for Perioperative Assessment and Quality Improvement (SPAQI) recommends holding Japanese knotweed for 2 weeks before surgery due to its multiple active compounds including resveratrol 1
• Japanese knotweed contains compounds that may have antiplatelet effects and anti-inflammatory properties, which are the primary concerns in surgical settings 1

Use with Vyvanse

• There are no documented drug-drug interactions between Japanese knotweed and lisdexamfetamine (Vyvanse) 1
• The concerns about Japanese knotweed relate primarily to bleeding risk in perioperative settings, not to interactions with CNS stimulants 1
• If you are not planning surgery, Japanese knotweed can be continued alongside Vyvanse without expected pharmacokinetic or pharmacodynamic interactions 1

Milk Thistle

Drug Interaction Profile

• Milk thistle has a low likelihood of clinically significant drug interactions and can safely be taken with most medications 2
• Multiple studies demonstrate that milk thistle has minimal effect on phase 1 metabolic pathways in vivo, despite some in vitro inhibition data 3

Specific Considerations with Vyvanse

• Milk thistle does not interact with the metabolic pathways relevant to lisdexamfetamine 2, 3
• Lisdexamfetamine is a prodrug that is hydrolyzed to d-amphetamine in the blood (not via cytochrome P450 enzymes), making CYP-mediated interactions irrelevant 4
• The primary concern with milk thistle involves CYP2C9 substrates like warfarin, not amphetamines or their prodrugs 5

Safety Data

• Systematic reviews confirm milk thistle can be safely combined with most medications, with certain caveats primarily related to anticoagulants 2
• In vivo human studies show milk thistle has minimal effect on drug metabolizing enzymes compared to in vitro predictions 3

Clinical Recommendations

For Routine Use

• Continue both supplements with Vyvanse without dose adjustments 2, 3
• No monitoring beyond standard ADHD medication follow-up is required 4

Perioperative Planning

• Discontinue Japanese knotweed 2 weeks before any planned surgery 1
• Milk thistle can be continued perioperatively unless you are taking warfarin or other CYP2C9 substrates with narrow therapeutic indices 1, 2

Important Caveats

• The quality and composition of herbal supplements vary significantly by manufacturer and batch 6
• Always disclose all supplement use to your prescribing clinician, as approximately 75% of patients fail to report supplement use 2
• If you develop any unusual symptoms (bleeding, bruising, changes in ADHD symptom control), report these immediately 1, 2