Our evidence criteria

The London Pharmacopaeia strictly includes only those herbal uses that are supported by modern, evidence-based clinical research. We do not include or report uses based on traditional, historical, or anecdotal sources.

All therapeutic claims are classified based on the strength and type of scientific evidence available, as outlined below.

Clinical uses

For clinical uses, we use three categories.

Effective

A treatment is classified as Effective if it is supported by:

• One or more systematic reviews or meta-analyses published within the last 20 years

• These reviews must include high-quality human clinical trials showing clear and consistent therapeutic benefit

• Publications must be peer-reviewed and appear in reputable journals

Potentially Effective

A treatment is classified as Potentially Effective if:

• Supported by one or more controlled human clinical trials demonstrating positive outcomes

• Lacks recent systematic reviews or the body of evidence remains too limited for a full effectiveness classification

• No high-quality contradictory evidence is present

Not known to be effective

A treatment is classified as Not known to be effective if:

• Systematic reviews or multiple well-conducted clinical trials consistently show no therapeutic benefit

• There is no research available

Phytochemistry

Phytochemical profiles are intended to promote understanding, rather than for pharmacological use. For this reason, any reputable full profiles are included, categorised by the form of preparation tested.

Interactions, adverse effects, and contraindications

For safety reasons, any research indicating potential interactions with medications, adverse effects, or contraindications, is included.

Evidence considered

The London Pharmacopaeia prioritizes clinical evidence from:

• Systematic reviews (e.g., Cochrane, PubMed-indexed)

• Randomized controlled trials (RCTs)

• Meta-analyses

• Clinical pharmacopoeias and academic literature

• Official clinical guidance documents

Excluded evidence

The London Pharmacopaeia does not include any evidence based solely on:

• Traditional, folkloric, or historical practice

• Anecdotal or practitioner-reported benefits

Review and reclassification

London Pharmacopaeia monographs are periodically reviewed and updated. Classifications may change when:

• New systematic reviews or major trials are published

• Earlier data is contradicted or discredited

• National or international guidelines are revised