Sodium bicarbonate (baking soda) has a long history of traditional use in the management of various skin conditions, including psoriasis, due to its perceived soothing and anti-itch properties. People have commonly added it to bathwater or used it in pastes to help relieve itching and scaling associated with psoriasis. The rationale for its use is based on anecdotal reports and its ability to alter skin pH, which may temporarily alleviate irritation and discomfort.

However, the scientific evidence supporting sodium bicarbonate's efficacy for psoriasis is limited and of low quality. There are no large, well-controlled clinical trials that confirm its effectiveness. Some small studies and case reports suggest that baking soda baths may provide mild symptomatic relief, likely due to the moisturizing effect of soaking and the temporary reduction of itch. Major dermatological guidelines do not recommend sodium bicarbonate as a primary or adjunct treatment for psoriasis, instead favoring topical corticosteroids, vitamin D analogs, and other evidence-based therapies.

In summary, sodium bicarbonate's use for psoriasis is primarily supported by tradition and anecdotal experience rather than robust scientific validation. While generally considered safe for topical use in diluted forms, its therapeutic benefit for psoriasis remains unproven in rigorous studies.