DEAR DR. DONOHUE: I am interested in knowing more about eczema. I have it on my feet and hands. It gets itchy. It comes and goes. How does a person get this? Is it allergies? Can it spread? Is there a cure? – L.H.

ANSWER: Eczema is skin inflammation. It’s not exactly an allergy, but it is found most often in people who do have other allergies, like hay fever, or food allergies. The inflammation is brought about by the immune system reacting to something that remains unknown. Genes definitely are involved.

Inflamed skin loses its ability to hold water. Dry skin itches, and the itch can be exasperating.

The patches of involved skin turn red and often have tiny blisters – so tiny that they’re difficult to see without a magnifying lens.

Eczema can pop up anywhere, but it most often appears on the neck, the elbow crease, behind the knees, on the face, wrists, forearms, hands, feet and scalp. It can spread to other skin areas.

The urge to scratch the involved skin is all but irresistible, but it should be resisted. Easy for me to say, but hard for the eczema patient to do. Scratching causes bleeding and skin thickening, and it adds to the distress.

There isn’t a cure, but there are controls. Skin hydration is a primary goal.

Moisturizers like Eucerin, Cetaphil, Nutraderm, Vaseline and Aquaphor are easily found and should be used often, especially after bathing. Don’t take long, hot showers or baths. Use mild soaps. Don’t wear wool. Cool compresses ease itching.

Cortisone creams and ointments calm the inflammation. Two noncortisone products are Protopic ointment and Elidel cream.

They come with a cancer warning based on mice studies where large doses were used for prolonged periods. There is no evidence of a human cancer link, to date.

DEAR DR. DONOHUE: You wrote about menstrual cramps. I remember that, in high school, our physical-education teacher told us to kneel on the floor with one’s head touching the floor and hold that position.

It did help me, so I thought I would pass it along. – M.H.

ANSWER: That’s one I haven’t heard.

Menstrual cramps most often occur in a girl who has been having periods only for one or two years.

They’re contractions of the uterus. The uterus is a muscular organ. The contractions are stimulated by prostaglandins, hormonelike substances whose production is high at the time of a menstrual period.

Nonsteroidal anti-inflammatory drugs, NSAIDs – Advil, Aleve, Motrin and many others — can counter the effects of prostaglandins and are often successfully used for menstrual cramps.

Thanks for the tip.

DEAR DR. DONOHUE: We read in your column and heard in other places that Vicks VapoRub works well on toenail fungus.

Because my husband takes medication that is processed by the liver, oral nail fungus medicines are not an option for him. He tried Vicks.

We watched his toenail turn black. We wonder what happened. Should we continue or discontinue? – P.H.

ANSWER: Discontinue.

I have heard of the Vicks treatment, but I don’t remember endorsing it. I’ve also heard of vinegar treatment, which I can’t endorse either. I might have mentioned both as popular but unproven therapies. I suspect that people who claim cure with these treatments were treating something that wasn’t a fungal infection.

Vicks VapoRub has camphor, menthol and eucalyptus oil. I’m not aware that any of these ingredients has antifungal activity.

I don’t know why the nail turned black. It takes 12 or more months for the nail to grow from its base to the tip, so if the discoloration stays, it’s likely to stay a long time. Your husband could consult a dermatologist.

If you’re worried about the fungus, you can stop worrying. I have never heard of toenail fungus directly or indirectly shortening a person’s life. Only if the nail were painful would treatment be required.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www .rbmamall.com