Balsam, particularly in the form of balsam of Peru or balsam of Tolu, has a long history of traditional use to support the mucus membranes, especially in the respiratory tract. Historically, balsam resins have been included in herbal cough syrups, lozenges, and inhalants to soothe sore throats, ease coughs, and relieve symptoms of bronchitis. The resin's aromatic and mildly antiseptic properties were believed to help clear mucus and protect irritated mucous membranes. These uses are documented in traditional herbal medicine texts and pharmacopeias from Europe and the Americas dating back centuries.

However, rigorous scientific evidence supporting balsam's efficacy for mucus membrane support is limited. Some laboratory studies have suggested mild antimicrobial and anti-inflammatory properties, but there is a lack of well-controlled clinical trials validating its effectiveness for this purpose in humans. The main evidence for using balsam in this context remains anecdotal and historical rather than based on modern scientific research. Furthermore, balsam can be a potent allergen and may cause contact dermatitis or allergic reactions in sensitive individuals.

In summary, balsam’s use to support mucus membranes is primarily justified by traditional practices and historical precedent, rather than robust scientific validation.