DEAR DR. DONOHUE: I am seeing a doctor for weight loss. He has placed me on vitamin B-12 injections three times a week to increase my energy and my metabolism. Isn’t B-12 an iron vitamin/supplement? Will I overdose? Are there side effects? Will my organs be damaged? I am losing weight, but my energy hasn’t increased. — L.A.

ANSWER: Vitamin B-12 perks up people if they are deficient in it. A deficiency of this vitamin causes a very special kind of anemia, pernicious anemia. The vitamin is essential for the production of red blood cells. Anemia is a low red blood cell count.

Too little B-12 in the body also can lead to nerve damage.

A blood test measures the amount of B-12 a person has. It’s not an iron vitamin.

Vitamin B-12 is very safe. Side effects are few and not serious. An upper daily limit to the vitamin has never been established, partially because of its safety.

DEAR DR. DONOHUE: I have a friend who encourages her 16-year-old daughter to use tanning salons. Please write your discouraging advice. — V.M.

ANSWER: Your friend hasn’t been living on planet Earth. Dermatologists have been preaching for years that people should limit their exposure to ultraviolet rays. Both ultraviolet B and ultraviolet A can lead to skin cancer. Ultraviolet A is delivered in tanning salons.

Teenagers believe they are immortal and immune from all illness. Parents need to step in when they are engaged in behavior that is dangerous to their health. If the young woman remains unconvinced of the risk of ultraviolet light, perhaps an appeal to vanity will set her straight. These rays cause premature wrinkles, make the skin leathery and can produce unappealing and permanent color changes.

DEAR DR. DONOHUE: What is the procedure for removing a tick attached to your skin? Can you remove it yourself, or should it be removed only by a physician? — T.R.

ANSWER: It’s safe for people to remove ticks on their own. You need tweezers with fine grooves on their lower, inner surfaces.

Grasp the tick as close to the skin as you can and as close to the tick’s head. Gently but firmly pull the tick straight out, at a right angle to the skin. Don’t crush it.

Don’t bother with popular techniques such as coating the tick with petroleum jelly or applying a just-blown-out match to it.

DEAR DR. DONOHUE: If a person takes medicine for hypertension, cholesterol, triglycerides and an anticoagulant, must he refrain from using Cialis or Viagra? — G.W.

ANSWER: Nitrate medicines, used for chest pain of angina, ought not to be used with Viagra, Cialis or Levitra. The combination might cause a dangerous drop in blood pressure. Alpha blockers used for blood pressure control are another possible danger. Those medicine are prazosin (Minipress), terazosin (Hytrin) and doxazosin (Cardura). It’s a good idea to check with your doctor if you’re on any high blood pressure medicine.

TO READERS: Peripheral artery disease, also called peripheral vascular disease, is a blockage of leg circulation that cause leg pains when a person walks. It’s a very common disorder.

The booklet on peripheral vascular disease describes it and its treatment. Readers can order a copy by writing: Dr. Donohue — No. 109, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

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.