“It has no risk — except boredom,” Dr. Dalton said wryly.
Before you begin, however, it is wise to rule out other conditions that could be affecting your sense of smell.
“I saw somebody recently who had smell dysfunction following Covid-19, and it turned out they had inflammatory nasal polyps,” said Dr. Sunthosh K. Sivam, an ear, nose and throat specialist and an assistant professor at the Baylor College of Medicine in Houston. Once he removed the polyps, which were unrelated to Covid, his patient’s sense of smell improved greatly.
“Seeing an E.N.T. is a good way to make sure nothing else is missed,” he added.
How do you choose your scents?
To start, decide on four scents that are familiar to you and that evoke strong memories, the experts said. These are the fragrances that you will stick with throughout the initial phase of your training. Maybe one of them is a scented shampoo, a favorite cologne or lemons from the tree in your backyard. An avid home cook, for example, might use certain spices from his pantry.
Alternatively, “some people have had a lot of success with things that smell bad,” Dr. Dalton said.
At one point during her smell training, Ms. Rao, the restaurant critic, used spoiled milk. Ms. Drager, who had Covid-19 over the summer, extinguishes a candle every day and tries to smell the smoke.
If that doesn’t sound appealing, you can choose to buy a smell kit that contains essential oils: the classic scents are rose, eucalyptus, clove and lemon. The kits usually retail for under $50.
Or you can purchase these oils yourself at a place like Whole Foods. Ms. Kelly includes instructions on how to make your own scent kit on the AbScent website.
If you buy your own oils and you want to smell them directly from the open container, first ask someone who isn’t smell impaired to try it. Then ask whether the person can easily smell the fragrance when the scent is a few inches below his or her nose. (Some containers have such small openings that it might be difficult to get a good whiff.) In the process, avoid getting any of the oils on your skin because they are highly concentrated.