Ivy, specifically Hedera helix (common ivy or English ivy), has a long history of traditional use for respiratory ailments such as coughs and bronchitis. Modern scientific research has provided moderate support for its efficacy in supporting the lungs and respiratory system. Extracts of ivy leaves contain saponins—particularly alpha-hederin—which are believed to have expectorant, bronchodilatory, and anti-inflammatory effects. Several randomized, placebo-controlled clinical trials and systematic reviews have reported that ivy leaf extracts can modestly improve symptoms in patients with acute or chronic bronchitis, such as reducing cough frequency and improving expectoration.

Ivy leaf extract is used as an ingredient in some over-the-counter cough syrups in Europe. It is generally well tolerated, but should be used with caution, especially in children under two years old. While the overall quality of evidence is moderate (rated 3/5), with some positive findings and some studies showing only mild benefit, the use of ivy for supporting lung health is justified by both traditional use and scientific validation. However, more large-scale, high-quality trials are needed to further clarify its efficacy and safety profile.

References:
- Holst, L. et al. (2011). "Ivy extract for acute upper respiratory tract infections: A systematic review of randomized clinical trials." Phytomedicine 18(2-3): 93-97.
- Schaefer, A. et al. (2016). "Efficacy and tolerability of ivy leaf extract in children with cough: A systematic review and meta-analysis." Phytomedicine 23(13): 1110-1114.