[citation needed] As a toxin, it can cause poisoning in monogastric animals, such as humans, through the consumption of raw or improperly prepared legumes, e.g., beans.

Recovery is usually spontaneous and rapid, occurring within three to four hours after onset of symptoms, although some cases have required hospitalization.

[10] In medicine these proteins are useful and are used as a mitogen to trigger T-lymphocyte cell division and to activate latent HIV-1 from human peripheral lymphocytes.

In neuroscience, anterograde tracing is a research method that uses the protein product phytohaemagglutinin PHA-L as a molecular tracer that can be taken up by the cell and transported across the synapse into the next cell thereby tracing the path of axonal projections and relative connections that nerve impulses travel beginning with the source located at the perikaryon (cell body or soma) and through the presynaptic part located on neuron's efferent axon all the way to the point of termination at the efferent synapse which then provides input to another neuron.

Peter Nowell, an immunologist and pathologist at the University of Pennsylvania in Philadelphia, was using PHA for this purpose in 1960 when he discovered it also had the ability to stimulate mitotic division of lymphocytes from normal peripheral blood.

T. C. Hsu's 1979 book "Human and Mammalian Cytogenetics an Historical Perspective" (ISBN 978-1-4612-6159-9) is an excellent resource for this history.