The short answer
Avoid self-starting oral chaparral while taking clozapine and discuss any current use with your prescriber. Chaparral has been linked to serious liver injury, and clozapine also has a liver-injury warning. Research has not shown how much, if at all, taking them together increases the risk beyond their separate effects.
What this answer covers
Oral chaparral products identified as Larrea tridentata. Evidence does not establish equivalent risks for other Larrea species, purified constituents or topical preparations.
- Supplement or preparation
- Larrea tridentata
- Medication ingredient
- clozapine
What is known about chaparral
A review of 18 adverse-event reports sent to the FDA found evidence of liver injury in 13. Some reports involved cirrhosis or the need for liver transplantation. These reports identify a serious concern but cannot tell us how frequently it happens among all users.
Why clozapine changes the discussion
Clozapine itself carries a warning for severe liver injury. Adding a supplement with its own liver-injury history creates another possible cause if liver tests become abnormal. This is a clinical precaution, rather than proof that chaparral makes clozapine more toxic.
Symptoms that need prompt attention
Contact your treating team promptly if you develop yellowing of the eyes or skin, loss of appetite, nausea or unusual fatigue. The clozapine label advises assessment and liver tests when liver injury is suspected. Tell the clinician about chaparral and any other supplements so the possible causes can be evaluated.
Practical next steps
Discuss the product and how long you have taken it with your prescriber. The available evidence does not establish a safe chaparral dose or show that taking it at a different time prevents liver injury. Medication decisions should come from the treating team, and the findings should not be extended to other plants or skin products.
Evidence and practical considerations
Side effects & toxicity
Oral chaparral and clozapine each have liver-injury concerns, supporting prescriber review before combining them; the added risk of the exact pair is unknown.
- Exact scope
- Oral Larrea tridentata products; case-specific preparation details remain incomplete. with Oral clozapine treatment.
- Medication form and route
- oral clozapine; oral supplement
- Timing or duration
- No pair-specific duration threshold is established.
What remains uncertain
- Spontaneous chaparral reports and clozapine labeling do not demonstrate synergy or quantify risk during co-use.
Factors that may matter: existing liver disease; other possible causes of liver injury; uncertain product composition.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed oral clozapine tablets.
Severe and sometimes fatal liver injury has been reported with clozapine. Signs and symptoms warrant serum testing and assessment of whether clozapine is responsible.
How this applies: Separate medication liver-risk context; does not prove synergistic liver injury with chaparral.
Does not study or quantify an interaction with the exact supplement.
Source 2: FDA adverse-event case series
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 18 reports to FDA during 1992-1994 after ingestion of chaparral.
13 reports showed hepatotoxicity; four progressed to cirrhosis and two involved liver transplantation. Symptoms appeared 3-52 weeks after ingestion.
How this applies: Supports a separate oral chaparral hepatotoxicity concern, not a measured added interaction risk.
Spontaneous reports cannot establish incidence; no clozapine-specific exposure or comparison is identified in the abstract.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Private evidence package and consumer draft prepared; clinical approval and publication are separate decisions. | |
| Research summary published |
Article revision: fb889b0c12fe0d75
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.