A case study published in the Journal for Nurse Practitioners provides evidence that antihistamines may help people suffering from long COVID. The study detailed how two middle-aged women saw a vast improvement in their symptoms after taking antihistamines every day.
The first woman, who is believed to be one first COVID cases in the United States, thought she had recovered from the viral infection. But two months later, her symptoms returned, and she began to experience "profound fatigue, malaise, and headache."
While she was dealing with long COVID, she inadvertently ate some cheese, which she is allergic to. She took 50 mg of the antihistamine diphenhydramine to treat her allergic reaction and started to notice her COVID symptoms improved. However, when she stopped taking the drug, her symptoms returned.
After taking the drug every day for six months, she went to her doctor, who prescribed her a 25 mg dose of hydroxyzine. Then, she increased the amount to 50 mg and reported that her symptoms had mostly gone away.
Another woman was dealing with long COVID symptoms for over a year. At the time, she was taking the antihistamine fexofenadine to treat seasonal allergies and asthma. When she ran out of fexofenadine, she switched to diphenhydramine and noticed that the symptoms of long COVID started to clear up the following day.
Since then, she has been taking 25 mg diphenhydramine at night and 180 mg fexofenadine in the morning. The report noted that her baseline functional status returned to 95% within 60 days.
The researchers said that more studies need to be done to determine if antihistamines can be used to treat long COVID.
"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 co-author Melissa Pinto, associate professor at the University of California, Irvine Sue and Bill Gross School of Nursing. "The possibility that an easy-to-access, over-the-counter medication could ease some of the [long COVID] symptoms should offer hope to the estimated 54 million people worldwide who have been in distress for months or even years."