The highest peak of aerial pollen counts comes in late summer. Golden rod, an abundant and conspicuous fall flowering plant, is largely, but erroneously, blamed as the culprit causing hay fever. The pollen, however, is heavy and sticky and adapted to insect pollination, NOT wind pollination. The sap is a milky latex and is toxic. The latex may cause general irritation of tissues and dermatitis.
Most severe irritation comes when eyes are rubbed after touching the sap.
One case of internal poisoning has been reported where included intense vomiting, catharsis and delirium. Urticacae Urtica spp. The numerous stinging hairs on stems and leaves act as tiny hypodermic needles, injecting the chemical irritant causing intense itching, usually of short duration. Contact with the resin often causes inflammation and swelling accompanied by intense irritation and followed by formation of vesicles or blisters. Careful washing of the exposed parts soon after contact will remove excess resin.