Medically Reviewed by Gabriela Pichardo, MD on June 13, 2020

Runny Nose: Cold


This is one of the most common causes of a runny nose. Other symptoms might include sneezing, a stuffy nose, and a sore throat. They come on slowly and usually go away on their own. You’ll feel better if you rest and drink lots of fluids.

Runny Nose: Flu


Flu symptoms appear quickly and often include fever, aches, and chills. Most people get better anywhere between a few days and 2 weeks, but antiviral treatments can shorten your illness by 1-2 days. Be on the lookout for complications among people at high risk such as young children, adults over 65, pregnant women, and people with conditions like asthma, heart ailments, and diabetes. 

Nosebleeds: Dry Sinuses


Parched air draws moisture from your sinuses, so they’re more likely to dry and crack. This makes it easy for bacteria to infect the area. Both conditions can cause bleeding. Use a humidifier to put moisture back into the air.

Nosebleeds: Hereditary Hemorrhagic Telangiectasia


This rare genetic disorder can weaken blood vessels and cause your nose to bleed more often for no clear reason. You might wake to a bloody pillow or notice small red spots on your hands or face. It can cause serious problems, such as a blood clot in your lungs or a stroke. Although it’s genetic, HHT may not show up until you’re older. Talk to your doctor if you notice symptoms or if you have relatives with the disease.

Nosebleeds: Other Causes


They range from allergies, hemophilia, and nose picking to blood thinners, aspirin, nasal sprays, and more. The bleeding itself isn’t usually serious. But see a doctor if you injure your nose, it bleeds for more than 30 minutes, or you can’t breathe properly.

Decreased Sense of Smell: Polyps


These growths in your nose are usually harmless, but they can prevent smells from getting to the right cells. Medication or minor surgery can get rid of them and make things as good as new.

Decreased Sense of Smell: Diabetes


Doctors don’t know exactly what the link is. High blood sugar may damage nerves, blood vessels, or organs that make up your complex sense of smell. Or it could upset your endocrine system, which could interfere with your sniffer. Learn the signs of diabetes and talk to your doctor about how to manage it or, better yet, prevent it.

Decreased Sense of Smell: Alzheimer’s


It might be an early sign of this or another brain condition, like Parkinson’s or Huntington’s disease, multiple sclerosis, or motor neuron disease. It’s best to catch these conditions early. See a doctor right away if you don’t notice smells as much as you used to or can’t tell one from another. Though it’s hard to treat illnesses that attack the nervous system, your doctor may be able to slow or ease some symptoms.

Phantom Smell: Brain Disorder


You may smell something that isn’t there. The aroma could be pleasant or nasty. You might have it in one or both nostrils. It could stick around or come and go. Causes include epileptic seizures, head injuries, brain tumors, or a condition like Parkinson’s disease. See your doctor right away to rule out these conditions.

Phantom Smell: Sinus Infection


Sinus infections can also make things taste unpleasant or bland. The phantom smell usually goes away on its own in a few weeks or months. Your doctor might suggest that you rinse your sinuses with a saltwater solution.

Red Nose: Rosacea


This condition causes the middle of your face to flush red. Over time, especially in men, it can thicken and redden the skin on the nose, a condition known as rhinophyma. In serious cases, it can change the shape of your nose and even make it harder to breathe.

Yellow Snot: Infection? Maybe


You can’t really tell exactly what’s going on just by the color of your snot. Colored mucus may be a sign of a virus or a bacterial infection, but it might also be due to an allergy, among other things. Your immune system uses white blood cells to get rid of bacteria. This turns your snot yellow as it fights the germs. After 10 or more days it might start to turn green. That’s when you may want to talk to your doctor about antibiotics. It should become clear after you get better.

Brown Snot: Air Pollution, Smoke, Dried Blood


If air quality in your area is so bad that it turns your snot brown, it’s probably a good idea to stay inside and avoid exercising outdoors. You can find out what the air’s like from your local weather report. Heavy tobacco use might also turn your mucus dark. So can dried blood.

Black Snot: Fungal Infection


Yes, it’s a real thing. It may mean that fungus is growing in your respiratory system. It could also be a sign of another serious medical condition that requires immediate care. Or it could be something ordinary, like dirt, smoke, or dried blood.

Clear Snot: Good Health


This is the kind you want! It’s usually a sign of good health, as long you don’t have too much. If there’s more of it than normal then it might be a sign of allergies, a cold, or the flu. Your doctor or pharmacist can help you manage allergies or a cold with over-the-counter medications. Talk to your doctor if you think you might have the flu. The doctor might suggest a prescription medicine to fight it and prevent complications.

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CDC: “Cold Versus Flu,” “Flu Symptoms & Complications,” “Flu Treatment,” “People at High Risk of Developing Flu-Related Complications.”

Cleveland Clinic: “When Do Frequent Nose Bleeds Signal Rare, Dangerous Disorder?”

Mayo Clinic: “Nasal Polyps,” “Nosebleeds,” “Phantosmia: What causes olfactory hallucinations?” “Rosacea.”

Journal of the Neurological Sciences: “Evaluation of olfactory dysfunction in neurodegenerative diseases.”

MedlinePlus: “Degenerative Nerve Diseases.”

Diabetic Medicine: “Association between diabetes mellitus and olfactory dysfunction: current perspectives and future directions.”

NIH News In Health: “What Your Nose Knows.”

NHS Choices: “Smelling things that aren't there (phantosmia).”

National Rosacea Society: “All About Rosacea.”

University of Utah Healthcare: “The Skinny on Snot.”

Harvard Health Publishing: “Don’t judge your mucus by its color.”