Rhus toxicodendron
Made from poison ivy — the plant whose resin, urushiol, teaches dermatology what allergic contact dermatitis is.
The whole picture, in one breath
Think of stiffness that loosens with movement: sore, bruised, restless, worse after rest and on first motion, better once moving around and from warmth. Cold damp weather sets it off; hot painful swellings, herpetic eruptions and blistered skin follow. Worse for rest, better for motion: that one keynote is Rhus tox.
The substance, in plain words
Poison ivy's clear resin, urushiol, is one of the most potent contact allergens known — a few micrograms raises blisters. The homeopathic preparation comes from the fresh leaves gathered at sunrise (the old method); its chemistry made it the prototype of allergic skin disease in modern dermatology.
The traditional picture Classical sources
The inner state
- Restless anxiety. Mentally and physically unable to rest; worry about the future, fear of poison, intense dreams of effort.
- Irritability at night. Cross, suspicious, worse at night with the pains.
- Fear of being poisoned. A characteristic anxiety recorded in the proving — the plant's own reputation speaking.
The body
- Stiffness worse for rest. The grand keynote: worse after sitting or lying, agony on first moving, relief from continued gentle motion.
- Sore, bruised, beaten feeling. Muscles and joints feel as if sprained or pounded; bed feels too hard.
- Better for warmth and rubbing. Warm applications and massage ease the soreness; cold and damp aggravate sharply.
- Herpetic and blistering eruptions. Clusters of burning vesicles — the books' great remedy for shingles-like eruptions and poison-ivy-type rashes.
- Ligaments and tendons. Sprains, strains and overlifted parts; left shoulder, small of back.
- Typhoid-like states. Restlessness, red-tipped tongue, joint pains in low fevers — a classical typhoid companion.
Modalities (worse and better factors)
| Worse from ⬇ | Better from ⬇ |
|---|---|
| rest and first motion; cold damp weather; getting wet; night; lifting and overexertion. | continued motion; warmth; rubbing and massage; dry warm weather. |
Where it acts (organ affinities)
Muscles, ligaments, tendons and joints, skin (vesicular eruptions), nervous system.
Where the classical picture comes from
Urushiol dermatitis was the best-known plant poisoning in America; the proving added the stiffness, restlessness and damp-weather aggravation. Clinically the remedy was built on sprains, herpes and the rheumatic complaints that followed wet weather.
The substance in real medicine Pharmacology
What this section is: the pharmacology and toxicology of the source substance. It is not clinical evidence that a homeopathic preparation of it treats any condition. What controlled trials do and do not show is set out on the Evidence page.
Urushiol is the model allergen of modern contact dermatitis: it is used under medical supervision in patch testing, and desensitisation research against poison-ivy allergy used urushiol extracts ('Rhus antigen') for decades. Poison ivy remains dermatology's standard example of delayed-type hypersensitivity.
Look-alikes (how the classical authors told it apart)
| Remedy | Looks similar because… | Tells it apart because… |
|---|---|---|
| Bryonia alba | Joint pains, irritability | Bryonia dares not move and is dry and thirsty; Rhus must move and is damp-weather-worse. |
| Arnica montana | Sore bruised feeling | Arnica follows injury and denies illness; Rhus follows damp exposure with stiffness relieved by motion. |
| Arsenicum album | Restlessness, anxiety | Arsenicum is chilly, fearful and burning; Rhus is sore, warm-better and stiff. |
| Causticum | Stiffness, paralysis tendency | Causticum is a dry-cold remedy with hoarseness and warts; Rhus is damp-heat with vesicles. |