Rhus toxicodendron is a tree from North America, from the anacardiaceae family known for its ability to produce very itchy cutaneous blisters by only touching slightly the leaves or even just by being exposed to the tree.
Its use in homoeopathy (after being diluted and dynamised) is influenced a lot by this toxicity. It is used on skin irritations that itch a lot such as chicken pox, shingles, simple lip herpes, eczemas, in the cases that include those conditions: it gets worse at night and improves when hot water is applied or with continuous movement.
Those same modalities help us prescribe the remedy in its second indication which is more common such as trouble with the locomotor limbs. It is used for pulled muscles, strains on tendons, ligaments or muscles, stiff neck, tennis elbow, lumbago after a strain... In this case, pain appears after a big effort that is followed by a sudden cooling (such as after running a marathon). The patient is very uncomfortable, he cannot stay sat down quietly because he feels worse and sleeps very badly, walking around the house or moving a lot in the bed searching for a position to feel better and changing position constantly. Very hot showers will bring relief but only temporarily. This is how this treasure is to be used frequently once we understand its use.
"It is used on skin irritations that itch a lot such as chicken pox, shingles, simple lip herpes, eczemas "