The plant whose berries are used in syrups and supplements intended to reduce cold duration is elderberry.
Elderberry usually refers to fruit from Sambucus species, especially European black elder (Sambucus nigra). The dark berries are used in syrups, extracts, gummies, teas, wines, and jams. Traditional medicine has used elder flowers and fruit for respiratory complaints, while modern supplements often market elderberry for cold and flu symptoms.
Some small clinical studies have reported shorter or milder cold symptoms among people taking elderberry preparations, including research involving air travelers. However, evidence remains limited, and there is no strong proof that elderberry prevents or cures colds. The question accurately describes how the berries are used, rather than claiming a definitively established treatment.
Raw or unripe elderberries, along with parts of the plant, can contain compounds that cause nausea or toxicity. Proper cooking or commercial processing matters. Cranberries, blackberries, and blueberries are also nutritious fruits, but elderberry is the canonical answer for traditional cold-relief syrups and supplements.