With summer now in full swing, let’s discuss a less than desirable effect of the hot, sunny weather: sun-induced reactions (photosensitivity) from medications!
You might be wondering:
- what is that?
- do my medications put me at risk?
- what do I do in case of such a reaction?
So here we go!
Sun-induced reactions to medications are of two main types: phototoxic or photoallergic.
Phototoxic reactions are far more common and look like sunburns. There may be blistering, lesions or skin swelling and they typically occur only on skin exposed to light. There are two main types of ultraviolet rays (UVA and UVB) that reach the earth. It is UVA light that can reach deep into the skin and react with some medications causing increased sensitivity to the sun. UVA rays coming through a window and fluorescent lights can also cause a reaction.
Photoallergic reactions only show up in some people. They involve the immune system, cause very itchy skin and may spread to areas of the skin that are not exposed to light. Compared to phototoxic, photo-allergic reactions can continue even when a medication is no longer present in the body.
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Some common medications that can cause photosensitivity reactions include:
- antibiotics
- tetracycline (e.g. doxycycline and tetracycline)
- fluoroquinolone (e.g. ciprofloxacin and moxifloxacin)
- sulfonamide antibiotics (e.g. sulfamethoxazole/trimethoprim)
- acne medications (e.g. isotretinoin and adapalene)
- diabetic medications (e.g. gliclazide)
- antidepressants (e.g. imipramine)
- water pills (diuretics) (e.g. hydrochlorothiazide)
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If you are on a photosensitizing medicine, you can prevent developing a reaction by limiting the time you spend outside; however, this may be difficult! Therefore it is recommended to wear protective clothing (wide-brimmed hats, long sleeves and trousers) and apply sunscreen. The Canadian Dermatology Association recommends using a sunscreen with a sun protection factor (SPF) of at least 30 and one that offers broad-spectrum UVA protection.
The following are some tips for using sunscreen.
- Apply generously and evenly over all skin areas exposed to sun – including the lips, ears and tops of feet
- Apply 15-30 minutes before sun exposure
- Reapply after swimming or sweating
- Follow the teaspoon rule
- 0.5–1 teaspoonful on the face and neck
- 1–1.5 teaspoonful to arms, shoulders and torso
- 2–2.5 teaspoonful to the legs and the tops of the feet
- Lip balms with SPF should also be used to protect lips
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Here are some tips to help manage a reaction:
- use cool tap water compresses to relieve pain
- avoid going out in the sun to prevent further damage
- use skin protectants (e.g. petrolatum) to moisturize and hydrate the skin
- topical corticosteroids or oral antihistamines may be used for itchy skin
- consult with your pharmacist if experiencing pain
Monitor for worsening burn and pain for a day or two after sun exposure. If the reaction is severe or there are signs of infection consult your doctor.
Talk to one of our pharmacists if you have any questions about sun-induced reactions.