Dear Doctor: My wife wants me to quit eating black licorice because she heard it’s bad for you. I think it’s just that she can’t stand the taste of it herself. I told her I was writing this email, and she said I have to include that I’m 42 and on blood pressure meds.

Dear Reader: Your wife is remembering a warning about black licorice issued by the Food and Drug Administration in 2017, just a few weeks before Halloween. Considering that Americans now spend upward of $2.7 billion (yes, with a B; and yes, we’re kind of shocked) per year on Halloween candy, the FDA’s timing seems spot on. According to the warning, “If you’re 40 or older, eating 2 ounces of black licorice a day for at least two weeks could land you in the hospital with an irregular heart rhythm or arrhythmia.”

To understand why, we need to talk about Glycyrrhiza glabra, the plant used to give licorice candy its distinctive flavor. Commonly referred to as licorice root, Glycyrrhiza glabra is a member of the pea and bean family, and is native to certain areas of Europe, the Middle East and western Asia. Its fleshy roots contain a compound called glycyrrhizin, which is 50 times sweeter than sugar.

Licorice root has medicinal properties, and it is a centuries-old treatment for a variety of ailments, including heartburn, stomach upset, ulcers, sore throat and bronchitis. However, one of the side effects of consuming glycyrrhizin is a potentially dangerous drop in the levels of potassium in the body. This means eating too much licorice can lead to a range of symptoms including high blood pressure, leg swelling, exhaustion, lethargy, cramping, abnormal heart rhythms and even congestive heart failure. Research shows that when you stop eating black licorice, potassium levels will usually return to normal on their own.

If you’re wondering why your wife wanted you to share your age and health status in your email, it’s because according to the FDA, people over the age of 40 who also have a history of hypertension or heart disease should be particularly careful not to eat too much licorice. Eating as little as 2 ounces -- that’s four small pieces -- of licorice every day for two weeks is enough to land someone in the hospital. Scientists at the National Institutes of Health, who take an even dimmer view of the candy, state that even 1 ounce of licorice per day consumed over the course of several weeks may be “potentially unsafe.” To avoid problems, black licorice lovers of any age should never eat large amounts of the candy at one time.

It’s also important to note that glycyrrhizin, the flavoring compound in licorice root, has the potential to interact with some medications, herbs and dietary supplements. For instance, the NIH warns that black licorice blunts the effects of the blood thinner warfarin, and it interferes with certain blood pressure drugs, steroid drugs and diuretics. If black licorice is a constant in your diet and you regularly take any medications or supplements, it would be wise to check with your doctor or pharmacist for any potentially adverse interactions.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My mom is 93, and her doctor says she needs a pacemaker to control a heart arrhythmia. How does a pacemaker work? Is the operation dangerous for someone her age?

Dear Reader: A pacemaker is a small medical device that uses electrical pulses to keep the heart beating at a steady rhythm. It may be needed to stimulate a faster heart rate in cases where the patient’s heart has begun to beat too slowly, or to correct potentially dangerous rhythm problems.

The device consists of two parts -- a battery-operated pulse generator, which contains a small computer chip, and between one and three fine wires, known as leads, which are tipped with electrodes. The generator, which is about the size of a matchbox or smaller, is surgically implanted beneath the skin of the chest, often near the collarbone. The leads are threaded through a vein that leads to the heart, and the electrodes are placed within those chambers of the heart that require outside stimulus. The specifics of the number of leads in a person’s pacemaker, as well as electrode placement, depend on the specific condition the pacemaker is treating.

Once the device has been implanted, the electrodes, which are sensors, read the electrical signals from the heart. They then transmit this data to the computer chip within the generator. Whenever an abnormal heart rate, or arrhythmia, is detected, the computer in the pacemaker instructs the generator to send corrective electrical impulses to the heart muscle. Adjustments can be made with a specialized computer called a programmer, which communicates with the pacemaker.

Pacemaker technology has benefited greatly from the tech revolution, and it continues to evolve. The earliest devices, which date back to the 1960s, were about the size of a hockey puck. Several years ago, a tiny pacemaker that’s smaller than a AAA battery won FDA approval. This device, which has no leads because it is placed directly in the chamber of the heart, is limited to certain patients with specific types of heart pacing needs.

The procedure to implant a pacemaker is performed in a cardiac catheterization lab, usually under small amounts of sedation in combination with local anesthesia. It’s considered to be a minimally invasive surgery, and it typically takes from one to two hours. Potential risks of the surgery include bleeding, infection, swelling or bruising, damage to the blood vessel used to guide the leads, or an adverse reaction to anesthesia used during the surgery. Patients either go home to recover the same day, or they spend one night in the hospital for observation. In the month following pacemaker surgery, patients must be careful to avoid vigorous exercise and heavy lifting.

About 400,000 pacemakers are implanted in the United States each year, half of them in people over age 75. And while surgery carries risks for people of any age, the complication rates of pacemaker implantation are low, including among patients who are in their 80s and 90s. Your mother’s own medical history is an important factor as well. We recommend that you speak with her cardiologist about the risks of the surgery versus the risks of going without it.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Some years ago, I was addicted to cocaine. I’ve overcome that addiction, but it has cost me my sense of smell. Why did this happen, and what can I do?

Dear Reader: It’s difficult to overstate the many ways we rely on our sense of smell. Not only does it provide a crucial connection to the physical world around us, but it’s a direct link to the events and feelings of our past. Whether it’s the scent of a wildfire on the way, the whiff of food going bad in the fridge, or the trace of perfume that instantly calls up memories of a bygone time and place, the sense of smell plays an important role in our safety and quality of life. It’s intricately tied to our sense of taste as well, as anyone who has tried to enjoy a favorite food with a stuffed nose knows all too well.

Our sense of smell, also referred to as olfaction, arises from the millions of specialized nerve cells, called olfactory sensory neurons, that are found in a small area of tissue located high up in the nasal cavity. Each time we breathe in, we inhale the millions of microscopic molecules that are being released by the environment around us. They rush up into the nose and stimulate the odor receptors found on those specialized nerve cells, each of which connects directly to the brain. The brain then interprets the chemical signals it receives as scent.

A diminished sense of smell, known as hyposmia, or a complete loss, known as anosmia, is often due to a blockage in the nasal sinuses, which prevents the scent molecules from reaching the olfactory neurons. This can be the result of inflammation, infection or injury.

Our sense of smell is also affected when the sensory neurons themselves get damaged. Although olfactory sensory neurons are continually replaced throughout a person’s lifetime, it’s possible for the damage or injury to be profound enough that the cycle of repair may be incomplete or even impossible. More rarely, smell disorders may involve injury, disease or dysfunction in the scent pathways within the brain.

Unfortunately, snorting cocaine can damage the inside of the nose in a variety of ways, including chronic constriction of blood vessels, atrophy of the delicate mucous membranes, damage to the flesh and cartilage, and permanent injury to the olfactory nerves themselves. We understand why you connect your diminished ability to smell with your previous cocaine use.

However, a number of other factors may be at play, which is why we think self-diagnosis is risky. Chronic sinus disease, a cold or the flu, injury to the nose or head, smoking, seasonal allergies and dental problems can often result in a diminished sense of smell. Aging plays a role as well, with one-fourth of people older than 50 experiencing hyposmia or anosmia. A diminished or lost sense of smell can be a symptom of conditions such as Alzheimer’s disease, Parkinson’s disease, polyps or tumors. With so many potential causes for the change to your sense of smell, we think it’s important to seek out a diagnosis from an experienced specialist.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)