Dear Doctor: What are the risks of a colonoscopy? Based on what I know about the procedure, it seems entirely likely that the colon could be damaged.

Dear Reader: Many people share your concerns, especially if they've never undergone the procedure. The first thing you should know is that colonoscopy is the gold standard in colorectal cancer screening. It can locate and remove polyps that may later increase the risk of colon cancer, and it's critical to the diagnosis of colon cancer in its early stages, when the disease is most curable. Colonoscopy may not be perfect, but studies have found decreased mortality rates among people who have a colonoscopy between the ages 50 and 75. That being said, the colonoscopy is not an entirely benign test.

First, there is the bowel preparation necessary to clear the colon. For some people, the medications to empty the bowels can cause abdominal bloating, pain, nausea, vomiting and alterations of the body's electrolytes.

Many patients who undergo colonoscopies are sedated prior to the procedure, and in people with a previous history of heart disease or severe lung disease, the sedatives can lead to abnormal heart rhythms, a drop in blood pressure and a decrease in the blood oxygen level. These problems are rare, but those with heart and lung disease should be aware of the risks.

After the preparation, the gastroenterologist inserts the scope and adds air to distend the colon, an act called insufflation. Here's where the primary risk comes in: The scope and the insufflation of the colon can indeed lead to perforation (tearing) of the colon. Perforations are more likely to occur after the age of 75; the perforation rate is nearly 6 times higher in that age group than in people under 60. Also, people who are ill from other diseases, such as heart failure, diabetes or cancer, have a greater rate of perforation. So, too, do those with diverticula of the colon (small pouches caused by weakness in the colon wall). Removal of a large polyp also increases the risk of perforation. Large perforations require surgical repair, while small perforations can be managed without surgery. Worldwide, perforation rates from a screening colonoscopy occur once in every 1,428 colonoscopies.

Other risks arise from polyp removal -- standard procedure upon their discovery -- because it can cause bleeding, and this risk increases in patients with a bleeding disorder. To reduce the likelihood of bleeding, all patients having a colonoscopy should stop taking any blood thinners several days beforehand.

As for infections, this complication is very rare and is related to defective equipment or improper cleaning of equipment.

The overall death rate from both screening and diagnostic colonoscopies is about 1 in 35,000, and the rates are continuing to decline.

Although there is a risk from colonoscopies, you should be aware that the risk of colon cancer is much higher -- more than 40 cases per 100,000 people each year in the United States -- and the colonoscopy is essential in the diagnosis of this and other colon diseases. If your doctor says you should have one, I would urge you to follow that advice.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Is it true that chemotherapy not only makes you lose your hair, but that it can also change the color and texture of hair that grows back, and even get rid of gray?

Dear Reader: We think your question may be addressing two different types of cancer treatment -- chemotherapy and immunotherapy. And in both cases the answer is yes; each can have an effect on the regrowth of hair.

After decades of use, much is known about the side effects of chemotherapy. These powerful drugs target cells in the body that grow and divide rapidly. However, chemotherapy drugs are indiscriminate. They can't tell the difference between the rapidly dividing cancer cells and the cells that form our hair, eyebrows and eyelashes.

Many cancer patients undergoing chemotherapy experience hair loss. Depending on the type of treatment, it can range from partial, with perceptible thinning of hair on the scalp and body, to complete hair loss, including body hair, eyelashes and eyebrows. When hair begins to grow back, usually three to six months following treatment, it can indeed be different from the hair that was lost.

For some patients, hair that was previously straight before treatment may grow back slightly coarse and quite curly. We've had some of our patients refer to this as "chemo curl." Changes in color, while not common, are also possible. Once the cells that control hair growth and color recover from the effects of chemotherapy and begin to function again, many patients find that their hair reverts to the color and texture it was before treatment.

Your question about cancer therapy returning color to gray hair makes us think you're talking about recent news stories emerging from the field of immunotherapy. Unlike chemotherapy, which directly targets cancer cells, immunotherapy drugs enlist a patient's own immune system in the fight against cancer cells. It's a new and often experimental approach to treatment, and the full range of potential side effects is not yet understood.

Last year, researchers followed 52 lung cancer patients who were each taking one of a trio of immunotherapy drugs in order to monitor any side effects the treatments might produce. They were surprised to see that 14 of the patients had their hair color go from gray to shades that varied from dark brown to black. One of the 14 patients had patches of black interspersed in his gray hair.

Of these 14 patients, 13 responded well to the immunotherapy drugs. This has led researchers to suspect that the change in hair color is linked to -- or is even an indicator of -- how well the cancer drugs are working. The researchers concluded that the sample size is small enough that these changes in hair color can be random flukes, so they plan to continue to investigate.

If you're hoping that immunotherapy can be used to reverse or stave off the onset of gray hair, you'll have to be patient. At this point in time, immunotherapy drugs have very serious side effects, so their use on otherwise healthy people is still a long way off.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My daughter, who is in her 40s, has fibromyalgia. Is there any cure for this painful condition, or any natural remedies? I hate to see her suffer.

Dear Reader: The word "suffer" perfectly sums up fibromyalgia, and my heart goes out both to your daughter and to you, who can see the condition's terrible effect on her. A chronic pain disorder initially termed "fibrositis syndrome" in the mid-19th century, fibromyalgia has been an official diagnosis only since 1990. The condition causes widespread musculoskeletal pain and fatigue, as well as sleep problems and difficulties in concentration and with memory.

In the United States, 2 to 3 percent of the population suffers from fibromyalgia, with women affected twice as often as men. Blood tests can't detect fibromyalgia, so the diagnosis is based on a person's symptoms, including the tender points identified during a physical examination. That said, people with fibromyalgia have shown abnormal biochemical responses to painful stimuli, and those responses can help guide treatment.

The first step in treating fibromyalgia is to understand the illness and what triggers a flair of symptoms. Anxiety and depression are common with fibromyalgia, and the resulting emotional stress can create a cycle of worsening pain and even lower energy levels.

Let's take a look first at non-medical interventions. Practicing good sleep hygiene is vital because poor sleep can worsen fibromyalgia pain and fatigue, and trigger the cycle mentioned above. Relaxation techniques and therapy can relieve anxiety and depression, while meditation training can ease pain. Further, reflexology and acupuncture have each shown benefits in small studies at easing a variety of symptoms.

Exercise is a crucial component of therapy. Multiple studies have shown that it decreases pain, increases flexibility and boosts energy. Note that if exercise is too vigorous or of high impact, it may cause a flair of symptoms. The key is to start slowly with low-impact exercise, such as walking, biking, swimming or water aerobics. As symptoms improve, patients can increase their level of exercise.

Although they don't cure the illness, various drugs and supplements can improve specific symptoms.

-- The antidepressants amitriptyline, duloxetine and milnacipran can be effective in several ways. Amitriptyline improves sleep, but can lead to dry mouth, constipation and grogginess the following day. Duloxetine can help ease depression or generalized anxiety and has been shown to reduce pain as well.

-- The muscle relaxant cyclobenzaprine can improve sleep and decrease fatigue. It also has been shown to reduce pain after four weeks of use, but not after eight weeks.

-- The anticonvulsants gabapentin and pregabalin can ease pain.

-- The synthetic cannabinoid Nabilone has shown some benefits in improving sleep, but none against pain.

-- Vitamin D supplementation has shown some efficacy against subjective feelings of pain.

Because fibromyalgia is a chronic condition, opiates are not recommended due to the likelihood of tolerance or addiction.

Yet, even with all these treatment options, the best hope is that people can find help controlling, if not curing, their specific symptoms.

Your daughter has one thing in her favor -- the fact that you are there for her and taking her condition seriously.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)