Q. I had COVID-19 in March 2020. My case was relatively mild, but I experienced terrible brain fog. I could not concentrate well enough to organize a simple budget or pay a few bills. After six months, I could not hold thoughts in my head long enough to make sure I was not making mistakes.

Then, I had an outbreak of cold sores. My primary care doctor prescribed an anti-viral drug called Valtrex. After two rounds of the medication, I noticed I was able to think far better than in the past six months. I can’t prove the Valtrex helped ease the problem, but that was the only change I made at the time. My thinking is that both cold sores and COVID-19 are viral diseases that might impact the brain. Could this antiviral drug have helped?

A. There is growing evidence that the virus that causes COVID-19 can affect brain function. That may be why so many long COVID-19 patients complain of brain fog.

There is also some research to suggest that the SARS-CoV-2 virus might reactivate a herpes outbreak (Cureus, Sept. 16, 2021). The antiviral drug valacyclovir (Valtrex) speeds healing from a herpes outbreak. It would be fascinating if it could also help ease the brain fog associated with COVID-19. Perhaps a researcher will follow up on your observation.

Q. My doctor recently doubled my amlodipine dose because my blood pressure was still too high. I’m now experiencing heart palpitations and an annoying post-nasal drip. Are these side effects of the medicine? My doctor thinks the palpitations are due to anxiety. I take Zyrtec and use nasal spray daily with no relief.

A. Your symptoms could certainly be side effects of your medication. In fact, palpitations are fairly common, especially among women.

The official prescribing information lists “rhinitis” (runny nose) as rare, but it has been reported. Perhaps it is time for your doctor to consider a different type of blood pressure medicine for you.

To help you with that conversation, you may find our “eGuide to Blood Pressure Solutions” helpful. In addition to the pros and cons of various medications, this online resource discusses approaches without drugs. You will find it under the Health eGuides tab at www.PeoplesPharmacy.com.

Amlodipine has been shown to reduce the likelihood of a heart attack or stroke (Cardiology and Therapy, December 2021). Some people find its common side effects such as fluid retention (edema), dizziness, flushing, palpitations, fatigue and digestive distress hard to handle.

Q. I have had an annual flu shot for over 30 years after experiencing two debilitating bouts of flu when I was a young mother. Never again!

Have I avoided the flu because of vaccines, healthy hygiene habits, eating a healthy diet devoid of sugar and processed foods, managing my weight, or popping a handful of immune-boosting supplements daily? I have worked with children for the past 15 years, so I have definitely been exposed. I’ll keep doing what I’m doing, vaccines included, regardless of how effective they may or may not be.

A. We won’t know exactly how effective this year’s flu shot is until next spring, when the data are in. The strains of flu that are circulating this year, however, seem to be well-matched by the antigens in the vaccine.

The flu season is especially bad this year. It hit early and hard. Your flu-fighting advice is quite sensible.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 628 Virginia Drive, Orlando, Fla., 32803, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”