Drug Reactions

Question 1

What is this a presentation of?

Generalised macules and papules on trunk +/- mild fever, no mucosal involvement.

Answer 1

Morbilliform drug reaction (measles-like)

Question 2

What are the causes of morbilliform drug reaction?

Answer 2

1. Amoxicillin (especially IM)
2. Cephalosporins
3. AED
4. Allopurinol
5. Diuretics

Question 3

What is this a presentation of?
Itchy, erythematous wheals (white lesions on red background), rapid appearance after drug exposure/allergy/infection. Can occur with angioedema/anaphylaxis.

Answer 3

Urticaria

Question 4

How long must urticaria be present for to be called chronic?

Answer 4

> 6 weeks

Question 5

What is the treatment for urticaria?

Answer 5

1. Antihistamine

2. +/- adrenaline and hydrocortisone in anaphylaxis

Question 6

What is Stevens-Johnson syndrome?

Answer 6

A severe immune complex-mediated hypersensitivity reaction (type III).

Question 7

What is this a presentation of?
URT symptoms 2-3 weeks after starting a drug. 2 days later, painful, rapidly spreading rash on <10% of BSA. Severe mucosal ulceration, breakdown of skin.

Answer 7

Stevens-Johnson syndrome

Question 8

What is the treatment for Stevens-Johnson syndrome?

Answer 8

Supportive, ICU, IV Ig, relieve pain.

Question 9

What is this a presentation of?
Flu-like symptoms preceding skin involvement affecting >30% BSA after taking drug. Mucosa severely affected, epidermal separation. Pyrexia, tachycardia.

Answer 9

Toxic epidermal necrolysis

Question 10

What is the spectrum of three drug reactions (mild to severe)?

Answer 10

1. Erythema multiforme - mild
2. Stevens-Johnson syndrome -moderate
3. Toxic epidermal necrolysis - severe

Question 11

Which medications can cause toxic epidermal necrolysis?

Answer 11

Phenytoin, allopurinol, penicillin, AEDs, NSAIDs.

Question 12

What is the treatment for toxic epidermal necrolysis?

Answer 12

Supportive, ICU, IV Ig, relieve pain.