Can cold and flu cause pityriasis rosea?

Can Cold and Flu Cause Pityriasis Rosea?

Cold and flu viruses are not typically considered primary causes of pityriasis rosea, but there have been rare case reports suggesting influenza virus may potentially trigger pityriasis rosea or reactivate other viral causes associated with this skin condition. 1

Etiology of Pityriasis Rosea

Pityriasis rosea is a common, acute, self-limited papulosquamous dermatosis with an uncertain etiology. The strongest evidence points to an infectious cause based on several epidemiological observations:

• Distinctly programmed clinical course
• Lack of recurrence for most patients
• Presence of temporal case clustering
• Seasonal variation
• Association with respiratory tract infections in some cases
• History of contact with pityriasis rosea patients in some cases 2

Viral Associations

The most commonly implicated infectious agents in pityriasis rosea are:

• Human herpesvirus 7 (HHV-7) - primary suspect
• Human herpesvirus 6 (HHV-6) - secondary suspect 3

There is reasonable evidence that pityriasis rosea is not associated with:

• Cytomegalovirus
• Epstein-Barr virus
• Parvovirus B19
• Picornavirus
• Influenza and parainfluenza viruses (with rare exceptions)
• Legionella species
• Mycoplasma species
• Chlamydia species 2

Relationship with Cold and Flu

While influenza viruses are generally not considered primary causes of pityriasis rosea, there is at least one documented case report of pityriasis rosea occurring concurrently with novel influenza A (H1N1) infection. The authors of this case report concluded that the influenza A virus could either be a primary cause or a trigger for reactivation of other viral causes (like HHV-6/7) 1.

More recently, similar associations have been observed with SARS-CoV-2:

• Pityriasis rosea has been reported in association with COVID-19 infection (both during and post-infection)
• It has also been reported following COVID-19 vaccination 4

These observations suggest that viral respiratory infections may occasionally trigger pityriasis rosea, possibly through immune system modulation or by triggering reactivation of latent herpesviruses.

Clinical Presentation and Diagnosis

Typical presentation of pityriasis rosea includes:

1. Herald patch (in ~80% of patients) - a larger, more noticeable oval or elliptical lesion that appears first
2. Secondary eruption - smaller (0.5-1 cm) oval lesions developing 4-14 days after the herald patch
3. Distribution pattern - lesions follow skin lines of cleavage (Langer lines)
   • "Christmas tree" pattern on the back
   • V-shaped pattern on the upper chest
4. Appearance - dull pink or salmon-colored macules with a delicate collarette of scales at the periphery 3

Prodromal symptoms occur in about 5% of patients and may include:

• Headaches
• Fever
• Malaise
• Fatigue
• Anorexia
• Sore throat
• Enlarged lymph nodes
• Arthralgia 3

Management

Pityriasis rosea is typically self-limiting with resolution in 6-8 weeks. Management options include:

1. Reassurance and symptomatic treatment - sufficient for most cases
2. Oral acyclovir - may shorten the duration of illness if active intervention is needed
3. Macrolides (particularly erythromycin) - may help in some cases
4. Ultraviolet phototherapy - may hasten resolution but carries risk of hyperpigmentation
5. Antihistamines and topical steroids - for relief of itching 3, 5

Key Takeaways

1. Cold and flu viruses are not typically primary causes of pityriasis rosea
2. Rare case reports suggest influenza may occasionally trigger or be associated with pityriasis rosea
3. HHV-6 and HHV-7 remain the most likely causative agents
4. The condition is self-limiting and typically resolves within 6-8 weeks
5. Treatment is mainly symptomatic, though acyclovir may be beneficial in shortening the course

When evaluating a patient with suspected pityriasis rosea who also has cold or flu symptoms, focus on the characteristic appearance and distribution of the rash rather than assuming a causal relationship between the respiratory infection and the skin condition.