Elderberry

• Upper respiratory tract infections (URTIs): Research suggests standardized elderberry (Sambucus nigra) extracts may reduce duration and severity of colds and influenza-like illness when started early; supported by a 2019 meta-analysis of small RCTs and individual RCTs, though heterogeneity and risk of bias temper confidence (moderate evidence).
• Symptom relief (fever, nasal congestion, cough): Several RCTs report faster improvement versus placebo in influenza-like illness; findings are not uniform across all studies (moderate evidence).
• Prevention: Limited evidence for preventing colds; one RCT in air travelers found reduced duration/severity among those who became ill but no clear reduction in incidence (emerging evidence).
• Antioxidant support: Elderberry is rich in anthocyanins; small human studies and mechanistic data indicate improved antioxidant status and anti-inflammatory signaling, but clinical relevance is uncertain (emerging evidence).
• Glycemic effects: In vitro and small preliminary studies suggest alpha-glucosidase inhibition and possible modest postprandial glucose-lowering; robust clinical confirmation is lacking (emerging evidence).
• Traditional use: Longstanding use in European herbal medicine for immune support and relief of fever/cough (traditional evidence).

• Common: Gastrointestinal upset (nausea, abdominal cramping, diarrhea), especially at higher doses or with concentrated syrups.
• Occasional: Headache, dizziness, mild allergic reactions (rash, itch) in sensitive individuals.
• Rare but serious: Toxicity from raw/underripe berries, leaves, or bark due to cyanogenic glycosides (e.g., nausea, vomiting, abdominal pain; rarely more severe symptoms). Proper cooking/standardized extracts mitigate this risk.
• Theoretical: Immune stimulation (in vitro cytokine upregulation) — clinical significance uncertain; caution in autoimmune/inflammatory conditions.
• Dose-related effects: GI symptoms more likely with larger syrup volumes or concentrated extracts.

Commonly used ranges in studies (not prescriptive):

• Syrup: Adults in influenza RCTs used approximately 15 mL four times daily for 5 days of a standardized elderberry syrup started within 48 hours of symptom onset.
• Capsules/Tablets: Standardized elderberry extract doses around 300–600 mg/day have been used; one RCT in air travelers used 600 mg/day for several days pre-travel, then 900 mg/day during travel.
• Lozenges/Teas/Juices: Composition and anthocyanin standardization vary widely; clinical dosing equivalence is unclear. Note: Preparations differ in anthocyanin content and standardization; optimal dose likely varies by product and individual. Do not consume raw or undercooked berries/leaves/bark.

• Pregnancy and breastfeeding: Insufficient reliable safety data — generally avoid.
• Autoimmune diseases (e.g., rheumatoid arthritis, lupus, multiple sclerosis) or history of cytokine storm: Potential immune-stimulating effects — avoid unless directed by a clinician.
• Organ transplant recipients or those on immunosuppressive therapy (e.g., for autoimmune disease): Avoid due to potential antagonism.
• Known allergy to elderberry/elderflower or plants in the Adoxaceae family.
• Children: Do not ingest raw/undercooked plant parts due to toxicity risk.
• Diabetes treated with glucose-lowering medications: Use cautiously and monitor glucose, as extracts may modestly enhance glucose lowering.
• Pre-surgical: As a precaution, discontinue at least 1–2 weeks before surgery due to potential effects on immune response and blood glucose.