The short answer
A lemon-balm extract reduced self-rated alertness in a small study, so extra drowsiness with clozapine is plausible. No direct study here shows the size or frequency of that effect. Check the exact preparation with the prescribing team and avoid hazardous tasks if you feel impaired.
What this answer covers
Melissa officinalis oral extract; the acute study used a standardized product. Tea, essential oils, other species and blends are not assumed equivalent.
- Supplement or preparation
- Melissa officinalis
- Medication ingredient
- clozapine
Why alertness may change
Clozapine can cause drowsiness and impair coordination. A standardized lemon-balm extract also reduced self-rated alertness in an acute human study. That combination of observations makes additional drowsiness plausible, but the two products were not tested together.
Dose and outcome matter
Eighteen healthy volunteers received 300 mg, 600 mg or placebo on separate days. At 600 mg, participants reported greater calmness and less alertness during a stress task. At 300 mg, mathematical processing became faster without lower accuracy. The results do not establish that every dose worsens cognition.
The study does not cover every product
The tested extract is not automatically equivalent to lemon-balm tea, essential oil or a blend. It also does not establish effects in people taking clozapine. Bring the product label and amount to a pharmacist or the prescribing team if considering it for stress or sleep.
Use symptoms to guide a review
Avoid driving or hazardous work if drowsy or impaired, and report persistent daytime sleepiness or unsteadiness. The evidence does not provide a safe spacing interval, a universal lemon-balm dose or a reason to reduce clozapine yourself.
Evidence and practical considerations
Side effects & toxicity
A standardized lemon-balm extract reduced alertness in healthy volunteers, providing indirect support for an added-drowsiness precaution with clozapine.
- Exact scope
- Melissa officinalis oral extract; the acute study used a standardized product. Tea, essential oils, other species and blends are not assumed equivalent. with Oral clozapine, RxNorm 2626 IN.
- Medication form and route
- oral clozapine; oral botanical preparation
What remains uncertain
- No co-use study; subjective alertness is not severe CNS or respiratory depression.
Factors that may matter: exact botanical preparation; other medicines; baseline drowsiness.
Read the supporting source summaries
Source 1: randomized human trial
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 18 healthy volunteers.
At 600 mg, self-rated calmness increased and alertness decreased during a stress task. At 300 mg, mathematical processing speed improved without reduced accuracy.
How this applies: Botanical-only evidence; relevance to clozapine requires separate interpretation.
Acute study in healthy volunteers; no clozapine exposure, severe CNS depression endpoint or general product threshold.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed clozapine.
Clozapine can cause sedation and impaired cognitive or motor performance; somnolence and instability can contribute to falls. Severe hepatotoxicity has been reported.
How this applies: Medication-specific safety context only; no direct botanical interaction or automatic dose change is established.
Does not name any of the six botanical counterparties or quantify their combined risks.
Research assessment: · Open full citations ↗
Side effects & toxicity
Clozapine-specific sedation risk, safe dose and spacing cannot be determined from the acute lemon-balm study.
- Exact scope
- Melissa officinalis oral extract; the acute study used a standardized product. Tea, essential oils, other species and blends are not assumed equivalent. with Oral clozapine, RxNorm 2626 IN.
- Medication form and route
- oral clozapine; oral botanical preparation
What remains uncertain
- Different population, preparation-specific doses and short assessment interval.
Factors that may matter: exact botanical preparation; other medicines; baseline drowsiness.
Read the supporting source summaries
Source 1: randomized human trial
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 18 healthy volunteers.
At 600 mg, self-rated calmness increased and alertness decreased during a stress task. At 300 mg, mathematical processing speed improved without reduced accuracy.
How this applies: Botanical-only evidence; relevance to clozapine requires separate interpretation.
Acute study in healthy volunteers; no clozapine exposure, severe CNS depression endpoint or general product threshold.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed clozapine.
Clozapine can cause sedation and impaired cognitive or motor performance; somnolence and instability can contribute to falls. Severe hepatotoxicity has been reported.
How this applies: Medication-specific safety context only; no direct botanical interaction or automatic dose change is established.
Does not name any of the six botanical counterparties or quantify their combined risks.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Preparation-specific evidence and uncertainty assessed. | |
| Research summary published |
Article revision: 4ab2b07a160b1f32
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.