Loss of the sense of smell usually means either that there is something wrong in the nose or sinuses, or (rarely) there is something wrong with the brain/nervous system, because these are the parts of the body that are involved in smelling. Some prescription medications can also interfere with smell. Your sense of smell and taste are connected, so taste problems often accompany problems with smell.

Let’s focus on sinus problems, as these are much more common than brain problems. (Also, as an allergist, I am in a good position to tell you about sinus problems, but I am not an authority on the brain.) Chronic inflammation of the nasal linings and sinuses lasting longer than three months (a condition called chronic rhinosinusitis) can lead to loss of smell and a bad taste in the mouth. The symptoms of chronic rhinosinusitis are nasal congestion or blockage, pain or pressure in the face, post-nasal drip (the sensation of mucus draining down the back of the throat), and decreased sense of smell. Most people with chronic rhinosinusitis have at least two of these symptoms. Many people also notice fatigue.

Some people with chronic rhinosinusitis form nasal polyps, which are small gelatinous globs of mucous and fluid that grow high up in the nose and occasionally can be blown out into a tissue. They look like small skinless grapes. Nasal polyps make the nose feel blocked most or all of the time, and people become very prone to sinus infections because mucus cannot drain out of the nose properly. People with nasal polyps often say that they cannot smell or taste their food. If you think you could have sinus problems, you could talk to your PCP. You may need to see an ear, nose and throat specialist or an allergist. Treatment to remove the polyps surgically or shrink them with medications can bring back your sense of smell.

There are various medications that can interfere with the sense of smell or give a bad taste in the mouth, or both. Some chemotherapy medicines can have these effects, but people are usually told about these side effects when they are treated. Certain drugs used to treat high blood pressure, such as amlodipine, diltiazem, and some ACE inhibitors, can interfere with smell. There is a long list of medications that give people a bad taste in their mouths, but these don’t usually affect smell at the same time. If you are or were taking any drugs when you had these symptoms, then check the side effects and see if they could be related.

Learn more in the Everyday Health Allergy Center.