Dear Doctor: Considering the recent news coverage of how hot-air hand dryers do little more than blow bacteria around, am I better off just wiping my hands on my pants when using a public restroom?

Dear Reader: First, let's consider why this would have seemed a ridiculous question only two decades ago -- before bathroom hand dryers had proliferated throughout the developed world. The use of paper towels in bathrooms had created concerns about environmental impact, both in connection to the trees used to make the paper towels and in the amount of trash produced. Bathroom hand dryers, although they used energy, decreased the use of, and trash from, paper towels -- not to mention they were (and remain) -- very cost-effective. The operation of bathroom hand dryers is only one-tenth to one-twentieth the cost of a year's worth of paper towels.

But, yes, now there are concerns about bathroom hand dryers and hygiene. In short, air hand dryers can aerosolize bacteria. A recent study at the University of Connecticut School of Medicine evaluated whether hand dryers contaminated the area around them with bacteria. The authors looked at three buildings within the school and placed bacterial growth plates (supplemented with sugar) in the bathrooms underneath the hand dryers. Each plate was placed 12 inches from the outlet of the hand dryer, left open to air for 2 minutes and then closed.

After 48 hours, the growth of bacteria was then measured. The plates near non-operating hand dryers grew 0 to 1 colony of bacteria. Those plates exposed to 30 seconds of air from operating hand dryers grew 18 to 60 colonies of bacteria, depending on the bathroom. That's a very big difference.

Multiple strains of bacteria, from 21 different species, were seen on the growth plates. The bacteria appeared not to come from the hand dryer itself, but from bacteria in the bathroom that was sucked into the air coming out of the fan. The reason: A high volume of air passes through these driers (19,000 linear feet per minute at the nozzle).

Two interesting notes: First, researchers saw no difference between women's and men's restrooms. Second, placing a HEPA filter within the hand dryer led to a fourfold reduction in the number of bacteria seen on the plates.

But because the hand dryers disperse bacteria does not necessarily mean they will increase the risk of infections, at least for most people. Those who have compromised immune systems, disruptions of the skin or intravenous lines, however, could potentially develop invasive infections. Furthermore, if you're washing your hands to prevent passing an infection to others, using a hand dryer may make the action moot. When you shake someone else's hand, you may transfer bacteria from the dryer air to them.

It may defeat the purpose of washing your hands in the first place, right? Not quite. The logic behind that conclusion is still hypothetical. A better study would be comparing the bacteria upon the hands of people who used either hand dryers or paper towels.

Until then, we're still not willing to suggest you dry your hands on your pants. It's simply better to use paper towels. Perhaps, sometime in the future, hand dryers with HEPA filters will become widely available.

(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: Years ago, I was told not to consume grapefruit or grapefruit juice with statins. Now I understand that this restriction no longer applies. Is this correct?

Dear Reader: The reason people are warned to steer clear of grapefruit when taking statins, which are drugs that lower cholesterol, is that certain compounds within the fruit and its juice affect the way the medications are absorbed. Known as furanocoumarins, they interfere with the metabolic processes that break down a range of medications, including statins. And while you're correct that there are now a few brands of statins that don't interact with those compounds, it's important to check with your pharmacist or physician regarding your particular prescription before adding grapefruit to your diet.

Statins are a class of drugs that get broken down with the help of an enzyme known as CYP3A4, which is found in the gastrointestinal tract and liver. It's a process that controls how much of a drug is released into the bloodstream, and it is factored into the calculations used to determine drug dosages. What happens in the presence of furanocoumarins, which are found not only in grapefruit but also in pomelos and Seville oranges, is the work of that key enzyme is inhibited. As a result, a larger amount of the drug than is intended enters the blood and accumulates in the body. In the case of statins, too much of the drug in the body can lead to grave complications, such as increased risk of damage to the liver and muscles, which can lead to kidney failure.

Grapefruit is a good source of vitamin C and has a bit of potassium as well, so patients often ask if there's a minimum amount they can safely consume while taking statins. Unfortunately, with many statins, the answer is still no. That's because we each secrete a different amount of the CYP3A4 enzyme in the small intestine. The same glass of grapefruit juice that would be safe for one person would be dangerous for someone else.

Interestingly, that same compound that generates an overabundance of statins in the blood will decrease the available amount of a few other drugs, including fexofenadine, an allergy medicine sold under the brand name Allegra. Apple juice and orange juice have the same effect on fexofenadine, which is why the labels on both the prescription-level and over-the-counter varieties of the drug carry a warning against taking it with any fruit juices.

An estimated 20 percent of the population between the ages of 45 and 70 are prescribed statins, so the fact that several of the brands now available do not appear to affect the CYP3A4 enzyme is good news. The statins that remain on the no-grapefruit list are atorvastatin (Lipitor), lovastatin (Mevacor) and simvastatin (Zocor). And while the current literature suggests that rosuvastatin (Crestor) and pravastatin (Pravachol) as well as a few other statin drugs have limited or no interaction with furanocoumarins, we urge you to check with your pharmacist or physician before adding grapefruit to your diet.

(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: After suffering from a metallic taste in my mouth for two years, I've been told by my doctor that I might be suffering from burning mouth syndrome. What can you tell me about this? I'm past menopause, take blood pressure medication, have had numerous X-rays and am pre-diabetic, all of which an internet search suggested might be factors.

Dear Reader: Burning mouth syndrome is a poorly understood chronic condition that leads -- just as the name says -- to a burning sensation within the mouth. The sensation occurs without any visible changes -- no lesions, no redness, just pain. The rate of the disease varies widely, but it appears to occur in about 1 in 1,000 people. The syndrome is rare in people under 30 and is most prevalent in those ages 60 to 80. Women are more afflicted than men by a ratio of 5-to-1.

Multiple theories have been proposed about the syndrome's cause, with a dysfunction of nerves that lead to the mouth being the most likely reason. These nerves fire abnormally, giving the sensation of pain even when there's no trauma to create pain. But then, the brain itself may play a role, possibly altering the sensory input received from the mouth. Also supporting a brain connection is the fact that the syndrome is frequently associated with stressful life events, sleep disorders, anxiety and depression.

Regardless, the pain is described as a scalding sensation, accompanied by tingling, numbness and a feeling of dryness in the mouth. A bitter or metallic taste (like you are experiencing) is noted in two-thirds of patients. The tongue is the most common area involved, but the pain can occur anywhere in the mouth, including the lips.

The syndrome is characterized by how often the symptoms occur. For 10 percent of people, the symptoms occur every few days; 35 percent of people experience the symptoms daily, but find them worse in the evening and reduced or absent in the morning; 55 percent of people have symptoms all day long.

As you have done, it is important to rule out specific causes for the burning sensation in the mouth. Vitamin deficiencies, diabetes, autoimmune conditions and certain types of chemotherapy or radiation can lead to mouth-related nerve damage. Infections, the antidepressant paroxetine and ACE inhibitors used for blood pressure can all cause mouth pain.

Treating the syndrome can be difficult. Topical medications such as capsaicin (from chili peppers), clonazepam, lidocaine and doxepin can deaden the nerve stimuli in the area of pain. In small studies, the antioxidant alpha-lipoic acid has shown benefit in 35 to 70 percent of people with the syndrome when taken at 600 milligrams per day.

Because of the psychological issues often associated with burning mouth syndrome, cognitive behavioral therapy can be effective in reducing pain, as can antidepressants -- SSRIs, SNRIs and tricyclic drugs, like amitriptyline. Drugs used for nerve pain, including gabapentin and pregabalin (Lyrica), may also help.

Unfortunately, burning mouth syndrome can last for months to years, with many people having some degree of symptoms even after five years. So it's best not to simply hope that it will go away. Severe symptoms warrant the use of a topical medication, alpha-lipoic acid, cognitive behavioral therapy or even oral medications.

(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.)