Pharmacists Counsel Patients on Drugs With Heat and Photosensitivity Effects

Extreme heat is no longer a seasonal inconvenience—it is a documented driver of emergency department visits and hospitalizations. According to the CDC, hot days are associated with worse pregnancy and birth outcomes and increased hospitalizations for heat illness, cardiovascular and respiratory disease, asthma, diabetes, kidney disease, mental health conditions, and injuries.¹

The agency identifies infants and children, pregnant women, adults older than 65 years, people with disabilities, people with chronic health conditions, people with mental health conditions or substance-use disorders, and people who lack access to cooling as being at heightened risk.

“Heat-related counseling is important for a few reasons. For one, the warm weather increases the likelihood that people will be outside. Going to the ocean or lake helps us to cool down,” Kimberly M. Kelly, PhD, MS, FSBM, a professor at the University of Tennessee Health Science Center, said. “Meanwhile, being outdoors increases the likelihood of sunburns, which can increase our risk of skin cancer. Being in water can wash away our sunscreen. These are concerns for everyone in the sun.”

Where a patient lives also matters. Urban heat islands, common in low-wealth city neighborhoods with less greenspace and more pavement, trap more heat than surrounding areas, and rural communities face their own risks from limited access to cooling and greater travel distances to care. Layered on top of these social and environmental risk factors is a clinical one that often goes unaddressed at the point of prescribing: medications themselves.

“Pharmacists play an important role as some medications increase our risk for sunburn,” Kelly said. “Also, as the medication experts, pharmacists need to be knowledgeable on over-the-counter products, like sunscreen. Some people have allergies to ingredients in sunscreen.”

How Medications Undermine the Body's Cooling System

The CDC states plainly that medications and heat can interact, leading to potentially severe adverse effects, and that many medications—including OTC products—can impair heat tolerance and the body's ability to regulate its temperature.¹

“Even ibuprofen—a common over-the-counter pain medicine—can increase the risk of sunburn,” Kelly said. “Perhaps one of the best known for its phototoxic effects is doxycycline, a common antibiotic.”

A 2024 systematic review and meta-analysis in eClinicalMedicine put that warning to the test, reviewing 35 randomized studies to determine whether medications flagged by the World Health Organization actually worsen the body's core temperature response during heat stress.²

The review found that not all commonly cited drug classes carry equal risk. Medications with strong anticholinergic properties raised core temperature by 0.42°C at air temperatures of 30°C or higher, alongside reduced sweating and higher skin temperature, though this evidence was limited largely to the drug atropine. Nonselective beta-blockers, such as propranolol, raised core temperature by 0.11°C, and selective beta-blockers, such as atenolol, showed no effect.²

The sympathomimetic adrenaline raised core temperature by 0.41°C, and anti-Parkinson agents, including bromocriptine and combined levodopa-carbidopa, raised core temperature by 0.13°C. Notably, the researchers found no clear evidence that antidepressants, diuretics, antipsychotics, anxiolytics, or antihistamines altered core temperature during heat stress, and they cautioned that conventional public health messaging about drugs such as antidepressants may not be well supported by the underlying evidence.²

That nuance matters for counseling, but so does a major limitation the authors flagged themselves. Of the 353 study participants across all 35 trials, 95.5% were men, and the average participant age was younger than 30 years. The population most likely to be prescribed these medications in real life—older adults with chronic disease—was almost entirely absent from the underlying research.¹

What the Real-World Hospitalization Data Show

Where the clinical trial evidence is thin, a large real-world analysis fills in some of the gaps. A study of Medicare beneficiaries 65 years and older with chronic conditions—including heart failure, diabetes, dementia, chronic kidney disease, and chronic obstructive pulmonary disease—found that 42.1% of patients who were later hospitalized for a heat-related event had experienced a heatwave during the study period, and that heatwave exposure was associated with a 21% to 33% increase in heat-related hospitalization risk, depending on medication class.³

Importantly, several medication classes were tied to increased hospitalization risk even during nonheatwave summer periods. Rate ratios ranged from 1.16 for anticholinergic agents to 1.37 for antipsychotics, and loop diuretic use was specifically associated with heat-related hospitalization among patients with dementia, heart failure, and myocardial infarction. The study's authors concluded that older patients with chronic conditions may face heightened hospitalization risk from heat-sensitizing medications throughout the summer, not only during officially declared heatwaves, and they called for improvements to prescribing protocols and drug labeling to better communicate this risk to clinicians and patients.³

Sun Sensitivity: A Related but Distinct Risk

Heat tolerance is not the only medication-related risk that intensifies with sun exposure. A separate mechanism—drug-induced photosensitivity—covers phototoxic and photoallergic skin reactions that occur when a photosensitizing drug absorbs ultraviolet or visible light. Phototoxic reactions can appear within minutes to hours of the first sun exposure and are dose-dependent, while photoallergic reactions are immune-mediated, require a prior sensitization period, and can occur even at low drug doses.⁴

The list of implicated drug classes is broad and includes several products pharmacists dispense daily: nonsteroidal anti-inflammatory drugs (NSAIDs) such as ketoprofen, which is the most frequent cause of photoallergy among topical NSAIDs; thiazide diuretics, which cause photosensitivity in an estimated 1 to 100 of every 100,000 treated patients; amiodarone, which causes phototoxicity in 25% to 75% of patients; tetracyclines and fluoroquinolone antibiotics; certain statins and fenofibrate; several antipsychotics and antidepressants, including phenothiazines and selective serotonin reuptake inhibitors; and antifungals such as voriconazole. Clinical symptoms typically appear on sun-exposed skin and include erythema, swelling, blisters, peeling, burning, itching, and hyperpigmentation.⁴

Beyond sun sensitivity from medication, being exposed to the sun can increase the risk of skin cancer.

“Everyone is at risk for developing skin cancer. However, people with lighter skin tones are at highest risk of skin cancer,” Kelly said. “Other groups that are at elevated risk are people with occupations or lifestyles that keep them out in the sun.”

In the Skin Cancer Awareness Now! project, which was used to promote skin cancer prevention and screening in community pharmacies, investigators found that community pharmacy is an effective location for skin care awareness, particularly in rural and medically underserved communities.⁵

“In our project, we help pharmacists to recognize the features of melanomas, the ABCDEs, as well as other concerning skin rashes. We have seen pharmacists who have identified concerning rashes while giving immunizations, with one pharmacist referring for what turned out to be an aggressive melanoma,” Kelly said.

Building the Counseling Conversation

The CDC's clinical guidance for health care providers centers on a 5-step patient management approach: assessing heat- and air quality-related risk factors, educating patients on staying cool, educating patients on hydration, educating patients on air quality, and making a medication management plan for HeatRisk orange, red, and magenta days. The agency also points clinicians toward a structured screening questionnaire to identify heat and air-quality risk factors during routine visits.¹

For pharmacists, this translates into concrete, recurring touchpoints. Every refill of a beta-blocker, diuretic, antipsychotic, or anticholinergic medication is an opportunity to ask how a patient is managing hydration and cooling on hot days, particularly for patients who are older, live alone, or lack reliable access to air conditioning—all factors the CDC identifies as compounding heat risk.¹ Every new prescription or OTC purchase involving a known photosensitizer is an opportunity to counsel on sun avoidance, protective clothing, and sunscreen, given how quickly phototoxic reactions can develop after exposure.⁴

“[Pharmacists] should be knowledgeable about potentially problematic ingredients in sunscreen,” Kelly concluded. “Perhaps the easiest thing that pharmacists can talk about is ‘slip, slop, slap, seek, slide’ from an Australian skin cancer program. Slip on protective clothing, slop on sunscreen, slap on a hat, seek shade, and slide on sunglasses.”

REFERENCES

1. Centers for Disease Control and Prevention. Clinical Overview of Heat. Heat Health. September 18, 2025. Accessed July 8, 2026. https://www.cdc.gov/heat-health/hcp/clinical-overview/index.html

2. Meade RD, Notley SR, Akerman AP, et al. The effect of prescription and over-the-counter medications on core temperature in adults during heat stress: a systematic review and meta-analysis. eClinicalMedicine. 2024;77:102886. doi:10.1016/j.eclinm.2024.102886

3. Bobb JF, Ho KK, Yeh RW, et al. Heatwaves, medications, and heat-related hospitalization in older Medicare beneficiaries with chronic conditions. PLOS ONE. 2020;15(12):e0243665. doi:10.1371/journal.pone.0243665

4. Kurpas M, Wysokińska E, Marcinek K, Rogoż K, Dwornicka K. Drug-Induced Photosensitivity—From Light and Chemistry to Biological Reactions and Clinical Symptoms. Pharmaceuticals. 2021;14(8):723. doi:10.3390/ph14080723

5. Kelly KM, Dhumal T, Scott VG, et al. SCAN! A pharmacy-based, sun safety feasibility study. J Am Pharm Assoc (2003). 2021;61(1):e69-e79. doi:10.1016/j.japh.2020.10.004