Old, dry skin (senile pruritus)
Atopic dermatitis (eczema)
Contact (allergic) dermatitis
Serious disorders not to be missed
Scabies (severe infestation)
Primary biliary cirrhosis/other causes (e.g. jaundice)
Generalised sensitivity (e.g. fibreglass, bubble bath)
Drugs (several types; see list)
Anaemia (iron deficiency)
Thyroid (hyper and hypo) disorders
Spinal dysfunction (nostalgia paraesthetica)
Is the patient trying to tell me something?
Quite likely: consider anxiety, parasitophobia.
Enquire about nature and distribution of itching. Consider pregnancy, liver disease and malignancy of the lymphatic system, particularly Hodgkin lymphoma. A careful review of any drug history is important. Note any associated general symptoms such as fever.
The itching of polycythaemia may be triggered by a hot bath and lasts for at least 1 hour.
Pruritus can be the presenting symptom of primary biliary cirrhosis and may precede other symptoms by 1–2 years.
The itch of Hodgkin lymphoma (in 30%) may be unbearable.
Drugs that can cause pruritus: aspirin, barbiturates, morphine, cocaine, penicillin, other antibiotics, anticytotoxics.