Rash After Sun Exposure - Sun Allergy

What Causes Photosensitivity (Photodermatitis)?

Photosensitivity can have various causes, just like most other symptoms.  Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.

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Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms.  In order to diagnose photosensitivity, we could:

  • Research the topic
  • Find a doctor with the time
  • Use a diagnostic computer system.
The process is the same, whichever method is used.

Step 1: List all Possible Causes

We begin by identifying the disease conditions which have "photosensitivity" as a symptom.  For example, lupus (SLE).

Step 2: Build a Symptom Checklist

We then identify all possible symptoms and risk factors of each possible cause, and check the ones that apply:
major joint pain/swelling/stiffness
history of non-vaginal candidiasis
very tender muscles
occasional mouth ulcers
fatigue after slight exertion
unexplained high fevers
history of candidiasis
chest pain when breathing
frequent sore throats
morning stiffness for 45-120 minutes
... and more than 10 others

Step 3: Rule Out or Confirm each Possible Cause

A differential diagnosis of your symptoms and risk factors finds the likely cause of photosensitivity.

Arriving at a Correct Diagnosis

The Analyst™ is our online diagnosis tool that learns all about you through a straightforward process of multi-level questioning, providing diagnosis at the end.

In the Environmental Risk Factors section of the questionnaire, The Analyst™ will ask the following question about rash after sun exposure - sun allergy:
Do you get a rash from the sun? This is not the same as a sunburn. Redness may appear after only minutes, sometimes accompanied by swelling, a burning sensation, itchy blisters, small or large raised/bumpy areas, pain, fever or nausea.
Possible responses:
→ Don't know
→ Never
→ Occasionally
→ Regularly on face/cheeks only
→ Regularly anywhere besides the cheeks
Based on your response to this question, which may indicate lack of photosensitivity, photosensitive rash, regular sun rash on cheeks or regular sun rash, The Analyst™ will consider possibilities such as Lupus, SLE (Systemic Lupus Erythematosus).  Approximately 80% of patients with SLE have dermatological manifestations during the course of their illness.  The acute skin eruption manifests itself as a photosensitive rash which often has a butterfly appearance and involves the bridge of the nose and cheeks.  A feature of this rash is a sparing of the crease seen on the sides of the mouth when smiling.  Photosensitivity is less common in patients of color but occurs in 50% of all patients with SLE.
Concerned or curious about your health?  Try The Analyst™
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