drug reactions

Question 1

what is a urticarial eruption

what hypersensitivity

Answer 1

An urticarial eruption is characterized by itchy red wheals (hives) with angio-oedema.
A wheal can last a few minutes and can change form.
Urticaria is type 1 IgE-mediated hypersensitivity reaction and so occurs very rapidly after taking the drug.

Question 2

how can a urticarial eruption be diagnosed

Answer 2

It can be diagnosed by a skin prick test and is treated with an antihistamine

Question 3

what can cause a urticarial eruption

Answer 3

NSAIDs
Beta-lactam antibiotics
Opiates
ACE-inhibitors

Question 4

what is a morbilliform eruption

Answer 4

A morbilliform eruption is characterised by a generalised maculopapular rash that is a very common complication of medications.
In children a similar rash is usually indicative of a viral exanthem (or measles in an unvaccinated child).
It is a type IV T cell mediated hypersensitivity reaction and so there is a delay of 1-2 weeks between starting the drug and the rash.
However on re-exposure the rash can appear much faster.

Question 5

what type of hypersensitive is a morbilliform eruption

Answer 5

4

Question 6

what causes a morbilliform eruption

Answer 6

Common causes include:

Amoxicillin - especially if the patient is also infected with EBV (glandular fever)
Beta-lactam antibiotics
Sulphonamides
Allopurinol

Question 7

what is a fixed drug reaction

Answer 7

A fixed drug eruption is characterised by circular, erythematous patches that may contain a blister that recur in the same location every time the drug is taken.
After healing, pigmentation may remain.

Question 8

what causes a fixed drug reaction

Answer 8

Paracetamol
Sulfonamides
Tetracycline antibiotics

Question 9

what is a lichenoid eruption

Answer 9

A lichenoid eruption presents similarly to lichen planus, although more commonly affects the trunk and Wickham striae are usually absent.
Lichenoid eruptions present with purple, pruritic, polygonal, planar papules/plaques.
Longitudinal ridging may be seen in the nails but the oral mucosa is not usually affected.
Typically a lichenoid eruption occurs 2 months after starting a medication.

Question 10

what causes a lichenous eruption

Answer 10

B-blockers
Thiazides
ACE-I
Antimalarials
Gold
Penicillamine

Question 11

how long does a lichenoid eruption take to occur after starting medication

Answer 11

2 months