Umckaloabo, also known as Pelar­gonium sidoides, is a herbal remedy traditionally used in South Africa for respiratory tract infections. In recent years, standardized extracts of Pelar­gonium sidoides root have been studied in Europe for their efficacy in treating acute upper respiratory tract infections, including tonsillitis. Several randomized controlled trials and meta-analyses have evaluated its effectiveness for acute tonsillitis, particularly in children and adults with non-streptococcal (viral) tonsillitis. These studies generally show that Umckaloabo may help reduce the duration and severity of symptoms compared to placebo, likely due to its purported immunomodulatory, antiviral, and antibacterial effects.

A 2013 Cochrane review and subsequent systematic reviews acknowledge a modest benefit for Pelar­gonium sidoides extract in reducing symptom duration of acute tonsillitis, though they also note that the quality of evidence is moderate and that most studies are sponsored by product manufacturers. The extract is considered safe with a low incidence of side effects, mostly mild gastrointestinal complaints. However, its effectiveness is mainly shown in cases of mild to moderate tonsillitis and should not replace antibiotics in cases of proven bacterial (especially streptococcal) infection.

In summary, while Umckaloabo has a traditional background, its use for tonsillitis is supported by some scientific studies, though the evidence is not strong (rating: 3/5), and further high-quality independent research is warranted.