DEAR DR. DONOHUE: For several years, I had ulcers inside my mouth. I visited an ear, nose and throat doctor, who had me stop all medicines, including medicines for cholesterol and osteoporosis, as well as vitamins. The sores cleared up, but they have returned. My cholesterol has risen without my medicine, and I am very careful about what I eat. I am worried about not taking my cholesterol medicine. What should I do? – C.R.

ANSWER: I assume you’re suffering from canker sores. Medicines can aggravate them, but a blanket condemnation of all medicines as being the sole cause is not warranted. You need a second opinion.

The actual cause of canker sores isn’t known. Some experts hold that they result from an immune-system reaction to mouth bacteria. Many people have an outbreak when they eat foods that cause trauma to the mouth lining – foods like pretzels or potato chips. Others find that nuts, chocolate and seafood trigger them. You have to keep a diary of what you eat and see if there is any relationship between food and your outbreaks.

For a few people, emotional or physical stress brings on a crop. In a very few people, vitamin deficiencies can be the cause.

Most canker sores heal on their own in four to 14 days. It doesn’t sound to me like discontinuing your medicine has cut down on the number of relapses you suffer or the length of an attack. I don’t buy the recommendation to stop all medicines without consulting the rest of your doctors.

Avoid abrasive, spicy, acidic foods and beverages. When there is an outbreak, using liquid Benadryl, milk of magnesia or Kaopectate as a mouthwash (don’t swallow them) can relieve the stinging pain. Aphthasol, a prescription medicine, is an oral paste that’s applied to each individual sore. Lidocaine viscous is another treatment that curbs the sting of canker sores. Kenalog in Orabase minimizes canker-sore irritation and promotes healing.

Do consult with the doctors who prescribed your medicines and see if they think it’s safe for you not to use them.

DEAR DR. DONOHUE: My granddaughter, almost 20, has had very irregular menstrual periods for some time. She goes three or four months without a period. She is very overweight. I say this is not normal. My daughter says she thinks it is normal for young girls to have irregular periods. My granddaughter is not pregnant and has never been pregnant, so this isn’t the problem. Please give some advice. – B.L.

ANSWER: In the first two years of menstruating, a young girl’s periods are often irregular. It takes time for the ovaries and the pituitary gland to synchronize their hormone production and for the uterus to respond to those hormones so regular menstrual cycles occur.

At age 20, it is not normal to have such erratic periods. Once a normal pattern is established, periods occur every 24 to 35 days and last three to seven days.

Your granddaughter could have a problem with hormone production, with her ovaries, with her pituitary gland or with her uterus.

You mention that she is overweight. That brings to mind polycystic ovary syndrome. Women with this condition often have infrequent periods, and often the menstrual flow is scanty. Many tend to be overweight. Since these women suffer from an excessive production of male hormone, they can develop facial hair and acne. Their ovaries are usually large and studded with cysts. There are many effective treatments for polycystic ovary syndrome.

You granddaughter needs to be examined.

DEAR DR. DONOHUE: How come you have never written about colitis? I would like to know about it, and I am sure other people would too. – D.E.

ANSWER: Colitis covers many different conditions: ulcerative colitis, mucous colitis, collagenous colitis and even irritable bowel syndrome. I have written about all of those.

Colitis also includes infections of the gastrointestinal tract, of which there are many.

If you drop me a line and let me know which kind of colitis you’d like information on or what kind of symptoms you have, I’ll oblige you.

DEAR DR. DONOHUE: My vitamin B-12 count was a little low. Can I double up on the vitamin? Is it safe for anyone to take the vitamin even if they aren’t deficient? – Anon.

ANSWER: The recommended daily allowance of vitamin B-12 for adult women and men is 2.4 micrograms (mcg).

You can safely take twice the RDA. No adverse effects have been seen even with very large doses of the vitamin. Unless a person needs such doses, they aren’t necessary, and they won’t do a person any more good than the recommended dose – but they won’t cause any harm either. It’s a very safe substance.

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.