Ask Your Pharmacist

May 19, 2022

I was only in the sun for five minutes last week, and I got a sunburn. Could this be related to the antibiotic I have been put on for my rosacea?


After the weather this past Saturday, we certainly are thinking more about how to protect ourselves from the sun's harmful light. To answer your question, yes, it is possible you had a skin reaction also known as a photosensitivity reaction from an interaction between the antibiotic you are taking and the sun's ultraviolet light. In fact, several prescription and over- the-counter medications can trigger toxic and allergic reactions to the sun's ultraviolet light. Photosensitivity reactions can develop as skin eruptions that appear as a rash. The skin may appear reddened, feel warm to touch, with pain and skin inflammation. Examples of medications commonly associated with photosensitivity reactions include antibiotics such as tetracycline, doxycycline, sulfamethoxazole/trimethoprim, and other medications such as nalidixic acid, voriconazole, amiodarone, hydrochlorothiazide, naproxen, piroxicam, chlorpromazine and thioridazine.  

The best way to deal with these types of skin reactions is to prevent getting them in the first place. Talk to your pharmacist when you start a new medication and discuss any precautions that may be necessary to prevent photosensitivity reactions. It may be necessary to stay out of the sun entirely when on certain medications. When this is not possible, it is important to cover up areas of the skin exposed to the sun and to use adequate sun protection. In some instances, after speaking with your doctor or nurse practitioner, it may be necessary to discontinue a medication that has caused a photosensitivity reaction.  

About 80 per cent of damaging ultraviolet light exposure occurs between 11:00 a.m. and 3:00 p.m. Take this knowledge into account when choosing outdoor activities. Wearing ‘sun-safer’ clothing with ultraviolet protective factor (UPF), ultraviolet protective eyewear, and wider brimmed hats, is especially important during these hours. If you already have sun damaged skin, avoid going out in the sun during these peak times. 

What is the difference between UVA and UVB?

Bottom line: both types of ultraviolet light, UVA and UVB, damage your skin in a way that leads to skin cancer. UVB is connected to sun protection factor (SPF) and is responsible for sunburns. Damage caused by burns is strongly linked to melanoma. UVA is connected to the term ‘broad spectrum’. UVA is associated with many types of skin cancer and may also cause sunburn. Health Canada advises choosing a broad-spectrum product with a minimum SPF of 30. Dermatologists advise, especially for those with pre-existing skin conditions or skin damage, to use an SPF of 60 or 70.

Which is better, sunscreen or sunblock?

Both types of protection are effective, if used properly. The key is to choose a product that is a good fit for your lifestyle. If you are not comfortable with the product, you aren’t going to use it. Test your chosen product on a small patch of skin first to see if it agrees with your skin. Sun blocks such as titanium dioxide and zinc dioxide act as physical barriers which tend to be thicker, and more visible on the skin. If you develop pimples easily, for example, this may be too much for your skin. 

Sunscreens containing active ingredients such as homosalate, oxybenzone, octocrylene, or avobenzon, are creamier but can run off quicker with perspiration and water. If using a spray-on product, spray your hands with the spray and then apply to your skin. This will help avoid getting the product in your eyes or mouth.

Choose a product with protection against both UVA and UVB that is water resistant. Be sure to check the expiry date of your sun care product.

How much sunscreen should I apply?

Follow the “Teaspoon Rule”. Apply one teaspoon (five mL) of sunscreen for the face, head, and neck. Apply one teaspoon each to the upper extremities. Apply one teaspoon each to the front torso and the back torso and two teaspoons each to the lower extremities. In total, apply nine teaspoons (45 ml) for the whole body. Apply 15 minutes before going outside and reapply every two hours.

Make protecting yourself against sun exposure part of your family’s life. For a list of dermatologist-recognized sunscreens, please go to the Canadian Dermatology Association:

Dr Kevin Duplisea (PharmD BSc. Pharm, BSc. ACPR) is a pharmacist In Quispamsis, New Brunswick. His opinions expressed in this newspaper are published for educational and informational purposes only, and are not intended as a diagnosis, treatment or as a substitute for professional medical advice, diagnosis or treatment. Send your questions to


Quispamsis pharmacist Kevin Duplisea dispenses information and advice on a wide range of pharmacy questions in a regular column published in several newspapers.

If you have a question you’d like to see answered in his column, you can send it to him at