Antihistamines show promise in treating long COVID-19 symptoms, UCI case report says

The effects of COVID-19 on individuals range from mild symptoms to several weeks of illness to ailments including brain fog, joint pain, exercise intolerance and fatigue that last for months after the initial infection. The clinical term for these lingering long COVID-19 effects is post-acute sequelae of SARS-CoV-2, for which there is no standard treatment.

"Patients tell us they wish more than anything that they could work and do the most basic activities they used to before they got sick with long COVID. They are desperately searching for something to help them get back on their feet," said the report's corresponding author, Melissa Pinto, UCI associate professor of nursing. "Currently, there is no cure for PASC, only symptom management. A number of options are being tried, with antihistamines being one of them. The possibility that an easy-to-access, over-the-counter medication could ease some of the PASC symptoms should offer hope to the estimated 54 million people worldwide who have been in distress for months or even years."

The case report, recently published in The Journal for Nurse Practitioners, describes two healthy, active middle-aged women with PASC who found, by chance, that antihistamines led to greatly enhanced daily function, now sustained for almost a year. Both took over-the-counter antihistamines to treat other conditions – the first one had triggered her dairy allergy by eating cheese, ­and the other had run out of the allergy medication she usually took – and experienced improved cognition and much less fatigue the next morning. The first woman's long COVID-19 symptoms also included exercise intolerance, chest pain, headaches, a rash and bruising, while the second coped with joint and abdominal pain, as well as the rashes and lesions known as "COVID toes."

In the first case, the woman didn't take another antihistamine for 72 hours; when her symptoms reappeared, she took the medication and again found relief. With guidance from her primary healthcare provider, who prescribed her an antihistamine, she began a daily dosage that has significantly decreased her other long COVID-19 symptoms. She reported that she has regained 90 percent of her pre-COVID-19 daily function.

In the second case, the woman took a different over-the-counter antihistamine as a substitute for what she had taken for years to manage her seasonal allergies. After noting that her long COVID-19 fatigue and cognition had improved, she continued to take it daily along with other allergy medicine. Her course of treatment, which now includes both over-the-counter medications, has also significantly reduced her additional long COVID-19 symptoms. She reported that she has regained 95 percent of her pre-illness functioning.

Previous studies, including those in the Journal of Investigative Medicine and Pulmonary Pharmacology & Therapeutics, have similarly shown the potential benefit of antihistamines as treatment for PASC.

"Most patients tell us that providers have not recommended anything that has helped. If patients wish to try OTC antihistamines, I urge them to do so under medical supervision. And because providers may not know about new potential treatments, I would encourage patients to be active in their care and consider taking research and case reports like ours to appointments with providers so they can help create a regimen that will work," Pinto said. "The next steps for this research into antihistamine treatment are to conduct broad-based trials in order to evaluate efficacy and to develop dosage schedules for clinical practice guidelines."

Additional co-authors on the report are Amir Rahmani and Candace Burton, UCI associate professors of nursing; Thomas Hughes and Heather Abrahim, UCI nursing science graduate students; Natalie Lambert, associate research professor of biostatistics & health data science at the Indiana University School of Medicine; Dr. Rana Chakraborty, pediatric infectious disease specialist at the Mayo Clinic; and Charles Downs, associate professor at the University of Miami School of Nursing & Health Studies.