Plectranthus amboinicus, commonly known as Indian borage or Cuban oregano, has a long-standing history of use in traditional medicine for various skin ailments, including boils. Ethnomedicinal practices, particularly in South Asia and Africa, document the external application of crushed leaves or leaf extracts to inflamed skin, abscesses, and boils. The rationale behind this usage is largely based on its reported antimicrobial and anti-inflammatory properties observed in folk medicine. Several in vitro studies have demonstrated that essential oils and extracts from P. amboinicus possess antibacterial activity against common pathogens, including Staphylococcus aureus, which is often implicated in the formation of boils. However, these studies are mostly preliminary, conducted in laboratory settings, and do not directly assess the clinical effectiveness of the plant in treating boils in humans.

There is a lack of well-designed clinical trials or robust scientific validation to confirm its efficacy and safety for this specific indication. The evidence supporting its use for boils, therefore, is primarily traditional, supported by ethnobotanical records and limited laboratory research, but not by rigorous clinical data. As such, while its use for boils is justified by tradition and some plausible scientific basis, the strength of evidence remains modest, warranting a rating of 2 out of 5.