Do all nettles cause irritation upon contact with the skin?

Not all nettles cause skin irritation. There are many different species of nettles, and only some of them have stinging hairs. The most common stinging nettle is Urtica dioica, which is found in Europe, Asia, and North America. Other stinging nettles include Urtica urens, which is found in Europe and Asia, and Urtica chamaedryoides, which is found in North America.

The stinging hairs of nettles contain a chemical called histamine, which is what causes the skin irritation. When the hairs are brushed against the skin, they break off and release histamine, which causes the skin to become red, swollen, and itchy. In some cases, the irritation can also cause blisters.

Not all nettles have stinging hairs. Some species, such as the dead nettle (Lamium purpureum), do not have any stinging hairs at all. Dead nettle is a common plant in Europe and North America. It is often used as a ground cover in gardens because it is easy to grow and does not require a lot of care.