Sunscreen Flashcards
What types of UV light exist?
UVA (so called tanning rays): used in suntan salons and photoreactions with drugs
UVB (“burning rays”): Vitamin D production
UVC: usually don’t reach the surface due to ozone layer
What is actinic keratosis?
They are considered a precancer, and are caused by exposure to ultraviolet radiation. They form on areas of the skin that are exposed to the sun (face, neck, shoulders)
Rate types of skin cancers by lowest to highest severity?
Basal Cell Carcinoma–> Squamous Cell Carcinoma –> Melanoma
What is the “ABCD” key to track the warning signs of melanoma?
A: Assymetrical in malignant, and symmetrical in benign cases
B: Border (uneven in malignant cases, even in benign cases)
C: Colour (various shades in malignant cases, single shade in benign)
D: Diameter (larger than 6mm in malignant cases, smaller than 6mm in benign cases)
What are some relevant effects of sun exposure?
Drug sensitivities (phototoxic and photoallergy)
Phototoxic: The drug causes increased irritation following exposure to skin (the most common sun-related drug interaction)
Photoallergic: The body has an allergic reaction to drugs following exposure to the sun (more splotchy compared to phototoxicity)
Sulfas, tetracyclines, NSAIDs, retinoids are affected by phototoxicity and photoallergy
Photo-aggravated disorders: Rosaceas
Certain wavelengths of light can help improve psoriasis symptoms
What does SPF (sun protection factor) represent?
The ratio between the time with sunscreen that results in minimal burn vs. time that causes a minimal about of burning unprotected
ex. Burning doesn’t happen until 120 minutes with protection, but in 30 without protection. SPF =120min/30min=4
SPF=4
therefore agents with SPF 45, allow you to stay 45x longer in the sun vs. being unprotected to get to the same amount of burning
What is the concern with higher SPF sunscreen agents?
They are safe agents on their own, but this might make patients overconfident about their protective properties. They might stay out too long and cause more damage
When should sunscreen be applied?
Apply 30 min before exposure
Apply every 2 hours
Reapply after swimming, water can slough off the layers (every 40-80 minutes)
Should we apply sunscreen on infants?
MInimum age is 6 months, babies before that age are usually not exposed to the direct sun anyways
Do sunscreens provide full protection against the energy?
No, not even close, but its better than being unprotected
Does sunscreen seep into the blood?
This is an unfortunate outcome, but the risk of sunburns is greater compared to sunscreen absorption into the blood. We still recommend sunscreens
What are some tan-promoting products?
Beta carotene (yellow pigment)
canthaxanthin
dihydroxyacetone (DHA) (pigmenting agent, reapply every 2 days)
What’s the best therapy for burns?
Run sunburned skin over water for 15-20 minutes
A dry skin lotion can be applied (keeps skin soft and reduces scarring)
lidocaine reduces pain, but 5% of people are sensitive
topical steroids are good for especially bad burns (blistering)
What are some de-pigmenting agents?
Hydroquinone (rx: 5% and cosmetics: 2%)
Monobenzene (rx only, but more potent)
