The second patient, a middle-aged teacher, has a similar story. A month after contracting SARS-CoV-2 – the virus that causes COVID-19, she was still suffering from joint pain, insomnia, a rapid heart rate, and difficulty concentrating. A year later, the symptoms remained debilitating.
One day, the patient randomly switched her antihistamine medication from fexofenadine to 25 milligrams of diphenhydramine, as the latter was more convenient to find.
The next morning, she noticed her brain fog and fatigue had improved, so she kept it up.
The patient now takes 25 mg of diphenhydramine at night and 180 mg of fexofenadine in the morning, and says she feels 95 percent better.