Learn About Smell Training Techniques

Understanding Smell Training and How It Works

Smell training, also called olfactory training, is a method of purposefully exposing yourself to different scents over a period of time. The basic concept involves regularly sniffing specific odors to help improve your sense of smell. This technique was first developed in the early 2000s by researchers studying people who had lost their sense of smell. Since then, it has become an area of ongoing scientific interest.

The human sense of smell works through the olfactory system, which includes receptors in the nasal passages that detect odor molecules. When you smell something, these receptors send signals to the brain. Over time, with repeated exposure to specific scents, your brain may become better at recognizing and processing those smells. This improvement can happen even if your olfactory receptors themselves haven't changed, because your brain is learning to interpret signals more effectively.

Smell training differs from simply smelling pleasant fragrances. The practice involves a structured approach where you focus attention on each scent, often for a set period of time. Participants typically use four different odors in a single training session. The goal is not to enjoy the smells necessarily, but to engage your olfactory system actively and deliberately.

Research has shown varying results with smell training. Some studies suggest it may help people with anosmia (complete loss of smell) or hyposmia (reduced sense of smell) notice improvements after several weeks or months of practice. Other research indicates that results depend on factors like the underlying cause of smell loss, how long the person has experienced the problem, and how consistently they practice.

Practical Takeaway: Smell training is a structured practice of regularly smelling specific scents with focused attention. Understanding that this works through brain adaptation rather than magical scent restoration helps set realistic expectations for what the practice might achieve.

Common Causes of Smell Loss That May Benefit From Training

Smell loss can occur for many different reasons. One of the most common causes in recent years has been viral infections, particularly respiratory viruses. Some people experience a sudden loss or significant reduction in their sense of smell following these infections. This type of smell loss is sometimes called post-viral anosmia or hyposmia. Studies indicate that hundreds of thousands of people worldwide have reported smell changes after viral illness.

Aging is another significant factor in smell loss. The sense of smell naturally declines as people get older. By age 65, roughly one-third of older adults notice changes in their ability to smell. By age 80, this number increases to about half of the population. This occurs because the olfactory receptors in the nose become less sensitive over time, and the brain processes smell signals less efficiently.

Nasal and sinus conditions can also interfere with smell. Chronic rhinosinusitis, polyps, or inflammation in the nasal passages can block odor molecules from reaching the olfactory receptors. In these cases, treating the underlying nasal condition may restore smell, and smell training might help during the recovery process. Allergies that cause nasal congestion can similarly reduce smelling ability temporarily.

Other causes of smell loss include head injuries, certain medications, nutritional deficiencies, and neurological conditions like Parkinson's disease or Alzheimer's disease. Some people experience smell loss after cancer treatment, particularly radiation or chemotherapy that affects the head and neck region. Smoking can also damage olfactory receptors and reduce smell sensitivity over time.

It's worth noting that smell loss can be temporary or permanent depending on its cause. Understanding what caused your smell loss matters because smell training may work better for some causes than others. For example, research suggests smell training may be more beneficial for people with post-viral smell loss than for those with smell loss from other causes.

Practical Takeaway: Smell loss has many different causes, ranging from viral infections and aging to nasal conditions and medications. Identifying what caused your smell loss can help you understand whether smell training might be useful for your situation.

Step-by-Step Guide to Practicing Smell Training

The basic smell training routine involves four distinct scents that you practice with regularly, usually daily or several times per week. Common scents used in training include rose, lemon, clove, and eucalyptus. These particular scents were chosen for research studies because they represent different types of smells: floral, citrus, spice, and minty. However, other scents can be used as long as they are clearly distinct from one another.

To begin your practice, gather four scent sources. Many people use essential oils, dried herbs in small containers, or scent samples. Each scent should be strong enough to detect but not overwhelming. Some people use small jars with cotton balls soaked in essential oil. Others purchase pre-made scent kits designed specifically for olfactory training. The containers should be easy to open and close.

Here's how a typical training session works: Sit in a quiet, comfortable location. Pick up the first scent container and bring it close to your nose. Breathe in the smell while focusing your attention on it. Try to recall if you remember this scent from your past, or think about what the scent reminds you of. Spend about 20 seconds concentrating on this smell. Then, set the container down and move to the next scent. Repeat this process with each of your four scents.

Complete this routine once or twice daily. Some research suggests that practicing twice daily may produce better results than once daily, though more research is needed on optimal frequency. Continue this practice for several weeks or months. Early studies involved training periods lasting three to six months, with some people practicing for longer. Improvement, if it occurs, often develops gradually rather than suddenly.

After several weeks, you may consider rotating your scents to introduce new odors to your olfactory system. Some people switch out one scent while keeping the other three the same. Others change all four scents. There isn't strong evidence yet about whether rotating scents produces better results than using the same four scents continuously.

Practical Takeaway: A basic smell training routine involves spending about 20 seconds concentrating on each of four distinct scents, once or twice daily, for several weeks or months. Consistency matters more than finding the "perfect" scents.

What Research Says About Effectiveness and Results

Medical research on smell training has produced mixed but somewhat encouraging findings. Several studies have documented cases where people practicing smell training experienced improvement in their sense of smell. A notable 2009 study published in the journal Laryngoscope found that people with post-viral smell loss who practiced olfactory training showed measurable improvements in standardized smell tests compared to a control group that did not practice training.

However, research also shows that results vary significantly between individuals. Not everyone who practices smell training experiences improvement. Some people notice substantial gains in their ability to smell, while others notice no change at all. Success appears to depend partly on what caused the smell loss in the first place. People with post-viral smell loss may be more likely to see improvement than those with smell loss from other causes.

The timing of when you start training may also matter. Some research suggests that people who begin smell training earlier after experiencing smell loss might see better results than those who wait months or years. However, case studies also document people gaining back some smell ability through training even years after the initial loss occurred.

Several factors may influence how much improvement a person experiences. Age appears to play a role, with younger people potentially showing greater improvement. The severity of smell loss at the start also seems relevant—some research suggests people with partial smell loss may improve more noticeably than those with complete loss. How consistently someone practices the training also influences outcomes, though the specific relationship between frequency and results remains unclear.

It's important to note that "improvement" in smell training research doesn't always mean returning to normal smell function. Sometimes improvement means noticing a few smells that were completely undetectable before, or smelling scents more faintly than before the loss. Complete restoration of normal smell is less common than partial improvement.

Practical Takeaway: Research shows smell training may help some people recover some smell ability, particularly those with post-viral smell loss, but results are individual and improvement is often gradual rather than complete.

Combining Smell Training With Other Approaches

Smell training works best as part of a broader approach to managing smell loss rather than as a standalone solution. If your smell loss results from a treatable cause, addressing that cause