Dear Doctor: I play in a weekend softball league, and my shoulder aches for a couple of days after the game. Aspirin hurts my stomach, so I wonder whether using a pain medication in a cream or an ointment might help?

Dear Reader: Thanks to effective over-the-counter drugs, banishing minor aches or pains is as easy as a trip to your medicine cabinet. These pain relievers, which are also used to reduce fever, fall into two main categories. One is acetaminophen, sold under the brand name Tylenol. The others are nonsteroidal anti-inflammatory drugs, or NSAIDs. Aspirin, ibuprofen and naproxen (sold under the brand name Aleve) are all NSAIDs.

As you have found, stomach upset can be a side effect of NSAIDs like aspirin. For people who prefer not to take ibuprofen or NSAIDs in pill form, topical pain relievers, which are applied directly to the skin, offer an alternative. The idea is that the medication, when placed on or near the point of pain, will be absorbed into the body, bypassing the stomach, and offer targeted relief.

A visit to the drugstore for a topical pain reliever can be confusing. Not only do you have your choice of creams, gels, foams, patches, sprays and (we're almost done) roll-ons, the products themselves fall into several distinct categories. Once you understand what they contain and how they work, you can decide what's right for you.

-- Topical NSAIDs: Yes, we're talking about aspirin, ibuprofen or naproxen again. However, studies show that blood levels of NSAIDs that are delivered through the skin are quite low, so potential for stomach upset is greatly reduced. What's important here is to follow the dosage recommendations. Don't use too much or reapply too often. And never use multiple NSAID products at once. Talk to your doctor about which ones to use, because they exist in both prescription and over-the-counter forms.

-- Capsaicin: This is the compound in chili peppers that gives them their kick. Topical products with capsaicin work by essentially desensitizing your body's pain response. However, some people find the burning sensation to be so intense that they are replacing one kind of discomfort with another.

-- Menthol: Like capsaicin, menthol is a counterirritant that creates a new, cooling sensation powerful enough to distract from the pain.

-- Methyl salicylate: Also known as oil of wintergreen, this is another counterirritant. It first makes the skin feel cool, and then feel warm. It's similar to aspirin, so be sure to read the label for counter-indications.

Finding a product you like may take some trial and error. When you do:

-- Remember that topical pain relievers are meant for pain that is mild to moderate.

-- They should be used for no longer than seven days, unless your doctor says otherwise.

-- Wash your hands immediately after applying the product.

-- Never use on an open wound or damaged skin.

-- Do not wrap or bandage the affected area until you're sure the product has been fully absorbed, as warmth and pressure may cause a higher level of absorption.

-- For that same reason, you should never use a heating pad with these products.

(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: I had my thyroid removed because of papillary cancer, and my surgeon has advised me to take high levels of vitamin D. He says there may be a correlation between low vitamin D levels and the development of cancer and Alzheimer's disease. If I remember correctly, the normal blood range for vitamin D is between 30 and 60 nanograms per millileter. I take 8,000 units a day, which keeps my blood level near 60 ng/ml. What's the evidence for higher levels of vitamin D?

Dear Reader: You and I share the same past cancer diagnosis -- and the same search for answers. When I was 26, I was also diagnosed with papillary thyroid cancer. At the time, I racked my brain for why I developed this cancer. I was healthy at the time, had a good diet and exercised regularly. I was also outdoors a lot, so my vitamin D levels were good.

As with so many cancer diagnoses, I ultimately couldn't find any factor that would have increased my risk. True, there is a definite link between papillary thyroid cancer and radiation exposure, which can come from radiation fallout due to nuclear accidents, as well as excessive X-ray radiation to the neck and oral area. But I hadn't been exposed to nuclear fallout, and I'd had only the normally recommended dental X-rays. (Today's more modern X-rays expose patients to lower doses than previous generations.)

I haven't stopped looking for connections, however, between a diagnosis of disease, risk factors and possible preventive measures.

That brings us to your current question. The normal blood level for vitamin D is between 20 and 50 ng/ml. This level -- generally considered necessary for good bone health -- is recommended by the Institute of Medicine, which conducted a review of studies on the topic. Some organizations, such as the National Osteoporosis Foundation, recommend 30 to 50 ng/ml as the normal range. But both of these recommendations are about good bone health, not the prevention of cancer and Alzheimer's disease.

The World Health Organization looked at multiple retrospective studies evaluating a potential connection between vitamin D levels and colon cancer. They did find a link between low vitamin D levels and colon cancer, specifically that people with blood levels of 20 ng/ml or less had significantly higher colon cancer rates.

However, retrospective studies look at disease after the disease has happened, and it can be difficult to make a solid correlation that way. A prospective study assessing vitamin D concentrations prior to the diagnosis of colon cancer did not find any evidence that vitamin D levels had any relation to colon cancer.

Studies focused on prostate cancer have shown both benefit and increased risk among people with higher levels of vitamin D, so it would seem that supplementation does not appear to have an impact one way or another. With regard to breast cancer after menopause, an analysis of nine prospective studies showed a decrease in breast cancer rates among women with higher levels of vitamin D, but this decrease was not seen in women whose levels were above 35 ng/ml. Still another analysis of 18 studies assessing overall breast cancer risk in women did not find any benefit to vitamin D supplementation.

In summation, there may be slight benefit to minimal supplementation in women after menopause to get their levels to 35 ng/ml to decrease the incidence of breast cancer. But in men, the benefit of reduced cancer risk has not been shown.

In relation to cognitive decline, a study published in the journal Neurology in 2012 showed a slight increase in Alzheimer's disease in people whose vitamin D levels were lower than 20 ng/ml. The authors concluded that more studies are needed to evaluate the potential connection.

Let's say that there is a benefit to vitamin D supplementation in lowering the risk of cancer and Alzheimer's disease. To reach a level of 20 ng/ml, you probably would not need to take more than 400 units of vitamin D per day. For a postmenopausal woman to reach the benefit needed for a possible reduction in the risk of breast cancer, she probably would not need to supplement with any more than 800 units per day.

In light of the evidence, 8,000 units of vitamin D daily seems too high. The blood serum level of 60 ng/ml also may be too high. Although the topic needs to be studied more, higher amounts of vitamin D could potentially lead to greater bone turnover and possibly weaker bones.

Ask your doctor if you can reduce the amount of vitamin D that you are taking, as there currently is no evidence to support it.

(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: I've read about a recent study that found that elderly patients with female doctors fared better than those who were treated by men. I wonder -- what do Dr. Ko and Dr. Glazier think about these results?

Dear Reader: You're referring to the results of a study performed by Harvard researchers, published in December 2016 in the journal JAMA Internal Medicine. To say that it caused a bit of a stir is an understatement. Our colleague Dr. Ashley gave his take on these findings yesterday. Our reactions follow later.

Researchers analyzed data from more than 1.5 million Medicare patients 65 and older who were hospitalized between January 2011 and December 2014. What they found was that patients whose doctors were women were less likely to be readmitted to the hospital in the next 30 days, and had lower mortality rates than the patients who were treated by men.

This particular study didn't look into the reasons why, but the authors cited prior studies that found differences in how women and men practice medicine. Specifically, the research suggests that female doctors are more likely to adhere to clinical guidelines, provide more preventive care and communicate more effectively than their male peers.

The Harvard study was prompted, in part, by the fact that women doctors now account for one-third of all physicians and one-half of medical students. Researchers were interested to learn whether career interruptions to start a family, the challenges of home-life balance, and the resulting increase in part-time employment might compromise the quality of care.

So what did we think of the results?

Dr. Glazier: My gut reaction is that it is very hard to generalize. As a patient, I have had both men and women who were extraordinary and compassionate physicians. And I have had teachers, mentors and colleagues who are exceptional, irrespective of their gender.

Considering that this is a single study of modest statistical significance, I don't give it tons of credence. What I would say is that it is paramount to find a doctor with whom you connect both personally and professionally, someone who is compassionate, kind and smart, all qualities that transcend gender.

Dr. Ko: As a female physician early in my career, I am naturally delighted to hear the findings. Medicine has historically been dominated by men, who have been seen as more intelligent and more capable than women. The results are validating and confirm my role to perform this noble work.

The authors admit they can't answer the question "Why?" But since prior studies suggest that women tend to communicate better, listen more effectively and have more emotional intelligence, then the message here is that communication is key. Our training of young physicians should focus on honing these skills and exemplifying these qualities.

The danger is that some patients may oversimplify these results, assuming that to prevent death and re-hospitalization, they need a female physician. But the truth is that there are as many male physicians who are compassionate communicators as there are women physicians who lack those qualities.

What I do hope is that all physicians will take a cue from these results to embrace the qualities and behaviors that may contribute to better care.

(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.)