Q. My dad is a good man. He is also an alcoholic.

He has been in recovery for seven years. Today, he admitted to my family that he has been getting drunk on Listerine!

A. Good people can sometimes become addicted to alcohol. We have heard from more than 100 readers about the dangers of drinking high-alcohol-content mouthwash. Some brands, like Listerine, contain as much as 26.9% alcohol. That’s about twice as much as wine.

Readers have described loved ones who died from liver and kidney damage after consuming large amounts of alcohol-containing mouthwash. This problem can affect people of all ages.

One reader wrote: “My elderly mother was drinking Listerine.

She had me and my sisters all getting it for her, and none of us was the wiser for a while. Now we have figured it out, so I told her I will no longer get it for her.

“She is going blind, and I am wondering if this is what caused her loss of eyesight. They say she has macular degeneration and glaucoma. Nothing more can be done for her eyes. She has drunk Listerine all her life and now she’s 94.”

Regardless of the source, alcohol can damage multiple organs. Medications such as naltrexone or acamprosate may be helpful in overcoming the addiction, along with counseling or AA.

Q. I read a question from a reader experiencing ear pain when flying. My solution for flights is to take Sudafed three hours before landing.

The decongestion medicine seems to open my sinuses, and I land without any pain in my ears.

A. Pseudoephedrine (Sudafed) is an oral decongestant that can open nasal passages. Since ear pain upon descent is related to changes in air pressure, it is not surprising that this medication could help. It is only available behind the counter, though, so people will have to ask the pharmacist for it.

Q. I developed Graves’ disease about a year ago. It caused a rapid heart rate, insomnia and hand tremors. I also lost weight without trying.

My doctor prescribed methimazole, which worked, but now I am hypothyroid. My hair is falling out, and I have no energy.

I have also gained back all the weight that I lost. What can I do to get back to normal?

A. It sounds as if your treatment for an overactive thyroid gland (Graves’ disease) might have been a bit too rigorous. Doctors need to tread a fine line when treating thyroid problems, since either too little or too much thyroid hormone can make a person feel ill.

Symptoms of hypothyroidism include dry skin, constipation, fatigue, puffy eyes, hoarse voice, slow pulse, depression, and hair loss. One unique feature that can be a tip-off to this condition is the loss of the outer third of the eyebrows.

We discuss symptoms and treatment of both hyper- and hypothyroidism in our “eGuide to Thyroid Hormones.”

Both fatigue and hair loss can be consequences of excessive thyroid hormone, just as from too little thyroid hormone. Your physician should help you adjust the dose of methimazole so that you do not have symptoms.

Sometimes the treatment for Graves’ disease results in an underactive thyroid gland.

The usual treatment for that is to take supplemental thyroid hormone, usually levothyroxine. You will also find an extensive discussion of this in our online resource, located under the Health eGuides tab at www.PeoplesPharmacy.com.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 300 W. 57th Street, 41st Floor, New York, NY 10019, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”