Spirulina can inhibit the formation or activity of histaminergic mast cells involved in inflammation and itching.

“if there are these so-called alternative therapies, alternative because most people haven't heard of them, it's always nice if they map to a specific logical mechanism and framework by which that compound would work, as opposed to just some anecdote of, "Oh, I hear spirulina is great for allergies." Well, now we know why, it inhibits mast cells and histaminergic mast cells in particular.”