Losing the sense of smell can be difficult and frustrating, says neuroscientist Richard Doty, PhD, FAAN, who directs the Smell and Taste Center at the Perelman School of Medicine at the University of Pennsylvania.

It also can be dangerous. A study in JAMA Otolaryngology—Head & Neck Surgery found that people who can't smell are almost three times as likely to experience a smell-related hazardous event—such as cooking or gas fires, undetected gas leaks, or eating spoiled food—as those with normal olfactory function. People should regularly check smoke detectors and natural gas monitors, stay close to the stove when food is cooking, and label leftover food with dates. They also should bathe and do laundry on a regular basis, says Dr. Doty.

After Karen Jentz first noticed a diminished sense of smell several years ago, her doctor told her to make sure she changed the battery in her smoke alarm regularly and set reminders when she was cooking. Having read about links between smell loss and Parkinson's or Alzheimer's disease, the 74-year-old retired teacher, who lives in Fairfield, IA, decided to participate in research to learn more. She contacted the Michael J. Fox Foundation for Parkinson's Research and was told about a study looking at people without Parkinson's or Alzheimer's to see if losing a sense of smell ups the risk of developing either disease years later. She completed the scratch-and-sniff test they sent her. “I did abysmally,” she says. “So now I'm participating in that study.”

Treatment for smell loss depends on the cause. For example, many drugs, including certain antibiotics, antihistamines, antihypertensives, and diabetes therapies, can interfere with the ability to smell. The solution can be as simple as changing the prescription.

A therapy known as olfactory training involves repeatedly sniffing specific scents while looking at a picture related to each scent to help stimulate the olfactory system and establish a memory of that smell. Jentz recently started olfactory training herself after her doctor recommended it. “These scents are strong enough that I actually can still smell them, and it's kind of pleasant,” she says.

Research suggests that olfactory training could be particularly effective for people who lost their senses of smell and taste because of respiratory infections. In a study published in Rhinology in 2016, 71 percent of patients with postinfectious olfactory loss improved over one year with olfactory training, while 37 percent of patients spontaneously recovered without training over the same period. About 20 to 25 percent of people with olfactory loss related to Parkinson's disease or trauma recover their sense of smell, per several studies.

Adding spices or marinating dishes in sweet or sour sauces can boost flavor, suggests Dr. Doty.

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