Published: 6 December 2019

Publications

Photosensitivity reactions – The other side of summer

Prescriber Update 40(4): 73–74
December 2019

As the weather gets warmer, consider the risk of photosensitivity reactions. Photosensitivity reactions occur with a number of medicines and result in sunburn or dermatitis on sun-exposed skin^1,2.

Drug-induced photosensitivity reactions occur after exposure to a topical or systemic photosensitising medicine and exposure to ultraviolet (UV) or visible radiation¹. The reactions can be classed as either phototoxic or photoallergic³.

Phototoxic reactions

Phototoxic reactions are more frequent than photoallergic reactions. They occur within minutes to hours after exposure to light and result from cellular damage^1–3. Signs include an exaggerated sunburn reaction, vesicles, blisters and bullae². The reaction is restricted to sun-exposed skin².

Photoallergic reactions

Photoallergic reactions are immune-mediated and take a longer time (24–72 hours) to appear after exposure to light^1,2. Photoallergic reactions are eczematous and itchy and may spread to non-exposed areas of skin².

Treatment

The best treatment option is to avoid the photosensitising medicine². If it is not possible to discontinue the medicine, the following sun protection strategies are recommended.

How to be SunSmart⁴

• Slip on a shirt/top with long sleeves and a collar.
• Slip into the shade.
• Slop on sunscreen that is at least SPF 30, broad-spectrum and water resistant. Apply 20 minutes before going outside and reapply every 2 hours.
• Slap on a broad-brimmed hat that shades the face, head, neck and ears.
• Wrap on close fitting sunglasses.
• Don’t use sunbeds.

Visit the SunSmart NZ website to learn more about staying safe in the sun.

What medicines cause photosensitivity?

A variety of medicines have been associated with photosensitivity reactions including antibiotics, cancer medicines, cardiovascular medicines, some decongestants and antihistamines, medicines to treat diabetes, diuretics, hormones, nonsteroidal anti-inflammatory drugs (NSAIDs), psychiatric medicines and retinoids^2,5. See the DermNet NZ website for a list of photosensitising medicines.

The arrival of summer is a good opportunity to review any new medicines started by your patients for photosensitivity. For example, vemurafenib (brand name Zelboraf) is a relatively new medicine that has been associated with mild to severe photosensitivity⁶. Patients should avoid sun exposure when taking Zelboraf⁶.

Refer to the medicine data sheet for further information on photosensitivity reactions for each specific medicine.

References

1. Blakely KM, Drucker AM and Rosen CF. 2019. Drug-Induced Photosensitivity-An Update: Culprit Drugs, Prevention and Management. Drug Saf 42(7): 827-47. DOI: 10.1007/s40264-019-00806-5 (accessed 15 October 2019).
2. DermNet NZ. 2006. Drug-induced photosensitivity. URL: www.dermnetnz.org/topics/drug-induced-photosensitivity/ (accessed 15 October 2019).
3. Khandpur S, Porter RM, Boulton SJ, et al. 2017. Drug-induced photosensitivity: new insights into pathomechanisms and clinical variation through basic and applied science. Br J Dermatol 176(4): 902-09. DOI: 10.1111/bjd.14935 (accessed 15 October 2019).
4. Health Promotion Agency and Melanoma Network of New Zealand (MelNet). 2019. New Zealand Skin Cancer Primary Prevention and Early Detection Strategy 2017–2022. URL: www.sunsmart.org.nz/sites/default/files/documents/1.0%20SS115%20Skin%20Cancer%20Strategy_Feb%202019_Online.pdf (accessed 20 November 2019).
5. Harvard Women's Health Watch. 2017. 10 types of medications that should keep you in the shade this summer July 2017. URL: www.health.harvard.edu/skin-and-hair/10-types-of-medications (accessed 17 October 2019).
6. Roche Products (New Zealand) Limited. 2017. Zelboraf New Zealand Data Sheet 5 September 2017. URL: www.medsafe.govt.nz/profs/Datasheet/z/zelboraftab.pdf (accessed 17 October 2019).