Question
A 36-year-old woman develops clearly defined, red, flaky plaques over the extensor aspect of her forearms. The lesions are interfering with her ability to handle her infant.
She had a cesarean delivery 5 weeks ago and has been using simple analgesics since then. She is not lactating.
Two weeks back, she was prescribed the following:
- A beta-blocker for episodic anxiety
- An antihistamine for sleep
- A short course of oral steroids for facial nerve palsy
Which of the following is the most likely trigger for her current skin condition?
a. Antihistamine medication
b. Simple analgesic use
c. Oral corticosteroid therapy
d. Hormonal increase during pregnancy
e. Beta-blocker therapy
Answer
e. Beta-blocker therapy
Explanation
This clinical picture is classic for plaque psoriasis, characterized by:
- Well-demarcated erythematous plaques
- Silvery scales
- Predilection for extensor surfaces (elbows, knees)
Among the options, beta-blockers (especially lipophilic ones like Propranolol) are well-known triggers that can:
- Induce new-onset psoriasis
- Exacerbate pre-existing disease
Why beta-blockers?
- They interfere with cyclic AMP signaling in keratinocytes
- This promotes keratinocyte proliferation and inflammation
- Lipophilic agents (e.g., propranolol) cross cell membranes more easily → stronger effect
Why not others?
- Antihistamines (e.g., Promethazine) → no association
- Paracetamol → not linked to psoriasis flares
- Oral steroids (e.g., Prednisolone) → may actually improve psoriasis (but withdrawal can worsen it)
- Pregnancy hormones → psoriasis usually improves during pregnancy due to immunomodulation; flares occur postpartum, not during progesterone rise
Cheat Sheet: Psoriasis Triggers
Drugs that worsen psoriasis:
- Beta-blockers (propranolol)
- Lithium
- Antimalarials (chloroquine, hydroxychloroquine)
- NSAIDs
- ACE inhibitors
- Interferons
Other triggers:
- Trauma (Koebner phenomenon)
- Alcohol
- Stress
- Infection (esp. streptococcal → guttate psoriasis)
- Withdrawal of systemic steroids
Flashcards
Q1. Which drug class is most commonly associated with psoriasis exacerbation?
A: Beta-blockers
Explanation: Particularly lipophilic ones like propranolol
Q2. What is the typical site of plaque psoriasis?
A: Extensor surfaces (elbows, knees)
Explanation: Classic distribution pattern
Q3. How does pregnancy affect psoriasis?
A: Usually improves
Explanation: Progesterone suppresses immune overactivity
Q4. What happens after steroid withdrawal in psoriasis?
A: Severe rebound flare
Explanation: Sudden immune rebound
MCQs
1. A patient develops new-onset psoriasis after starting medication. Which drug is most likely responsible?
a. Cetirizine
b. Propranolol
c. Paracetamol
d. Amoxicillin
Answer: b
Explanation: Beta-blockers are classic triggers; others are not associated
2. Which of the following is false regarding psoriasis?
a. It commonly affects extensor surfaces
b. Beta-blockers may exacerbate it
c. Pregnancy worsens it in most patients
d. Withdrawal of steroids can trigger flare
Answer: c
Explanation: Pregnancy usually improves psoriasis
3. Which mechanism best explains beta-blocker-induced psoriasis?
a. Increased histamine release
b. Reduced keratinocyte proliferation
c. Altered cAMP signaling in skin cells
d. Direct bacterial infection
Answer: c
Explanation: Beta-blockers reduce cAMP → increased proliferation
4. A patient on long-term steroids develops severe psoriasis after stopping them. This is due to:
a. Drug toxicity
b. Rebound immune activation
c. Allergy
d. Infection
Answer: b
Explanation: Steroid withdrawal leads to immune rebound
5. Which drug is least likely to worsen psoriasis?
a. Lithium
b. Propranolol
c. Paracetamol
d. Chloroquine
Answer: c
Explanation: Paracetamol has no known association
Summary for Quick Exam Revision
Plaque psoriasis presents with well-demarcated, erythematous, scaly plaques, typically on extensor surfaces such as elbows and knees. It is an immune-mediated condition driven by keratinocyte hyperproliferation. Several triggers can exacerbate psoriasis, with drugs being particularly important in exam settings. Among these, beta-blockers—especially lipophilic ones like propranolol—are high-yield causes. Other drug triggers include lithium, antimalarials, NSAIDs, and ACE inhibitors. Pregnancy generally improves psoriasis due to immunomodulatory effects of progesterone, while postpartum flares are common. Systemic corticosteroids may transiently improve psoriasis but their withdrawal can precipitate severe rebound flares. Recognizing drug-induced exacerbation is crucial, especially when new medications precede symptom onset.