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If you’ve ever had a runny nose or sneezed without a tissue, you’ve probably become close and personal with your snot. You may have noticed that it changes color or texture from time to time. Nasal discharge can be clear, green, black, and many other colors in between.

Your mucus is there to protect your nose and sinuses from things like dust, bacteria, and other environmental dangers.

Why might mucus change color? It usually has something to do with what’s going on inside or outside your body. You may be healthy or have a cold, allergies, or another underlying condition.

Here’s your guide to the different conditions that can affect the color of your snot, tips to find relief, and when to see your doctor.

Clear snot is considered “normal” or healthy. Your body produces around 1.5 liters of this discharge each day, though you likely swallow most of it.

This type of mucus is made up of water with proteins, antibodies, and salts. Once it reaches the stomach, it dissolves. Your body continues making it around the clock to help line and protect your nose and sinuses.

Allergic rhinitis or “hay fever” may also cause clear, runny nasal discharge. Although you may feel quite ill, allergies aren’t caused by a virus. The symptoms are your body’s response to irritants like pollen, cat or dog fur, and dust mites.

Some people develop a runny nose during pregnancy called nonallergic rhinitis. Researchers explain that this condition is caused by hormonal changes and can develop at any point during gestation. It’s more common between weeks 13 and 21. This condition usually resolves within a couple of weeks after delivery.

If you’re feeling congested or stuffy, you may notice your snot is white. You may also experience swelling or inflammation in your nose and a slow flow of nasal mucus.

Being stuffy makes your snot lose its water content. It becomes thick and even cloudy — both signs that you may have a cold or infection brewing.

The common cold can make you feel generally unwell. Your symptoms will usually develop between one and three days after being exposed to the virus. Children are particularly prone to colds. Adults, on the other hand, may experience between two and three colds each year.

Yellow mucus is a sign that whatever virus or infection you have is taking hold. The good news? Your body is fighting back. The yellow color comes from the cells — white blood cells, for example — rushing to kill the offending germs. Once the cells have done their work, they’re discarded in your snot and give it a dark yellowish tinge.

Your illness may last anywhere from 10 to 14 days, but keep an eye on your nasal discharge.

If your immune system kicks into high gear to fight infection, your snot may turn green and become especially thick. The color comes from dead white blood cells and other waste products.

But green snot isn’t always a reason to run to your doctor. In fact, some sinus infections may be viral, not bacterial.

Still, if you’ve had your cold or infection for 12 days or more, it may be a good time to make an appointment. You may have a bacterial sinus infection or another bacterial infection that requires medication. Look for other signs you’re not getting better, like fever, headache, or nausea.

Blood in your snot will tinge it pink or red. Blood may flow a bit if you’ve blown your nose a lot or if you’ve had some kind of hit to the nose.

People who are pregnant may also experience bloody snot. This may be due to blood volume increases, hormones, or swollen nasal passages.

If your child is experiencing bleeding, call their pediatrician. This is especially important if your tot is under age 2.

If your blood is the result of an acute injury like a car accident, seek medical attention to rule out more serious issues.

You should also see your doctor if you:

Brown snot may be the result of old blood exiting the body. Or you may have inhaled something red or brown that has discolored your mucus. Possibilities include dirt, snuff, or paprika.

Most commonly, people who smoke or are in households with smokers can have gray-black snot. Being subject to heavy air pollution may cause your snot to come out black. People who use drugs may also have black snot.

Black nasal mucus may also be a sign of a serious fungal infection. While not common, people with compromised immune systems may be susceptible to this type of illness.

There are four types of fungal infections of the sinuses:

Whatever the potential cause, it’s a good idea to check in with your doctor for a more formal diagnosis.

The actual texture of your snot has a lot to do with its moisture content. Nasal mucus that flows freely has more water content than snot that’s hard. In some cases, drinking more water may help thin your mucus. Changes in texture can happen throughout the duration of an illness.

Watery discharge from the nose may be a warning sign of a cerebrospinal fluid (CSF) leak. A leak happens when there’s a tear in the membranes surrounding your brain, likely from injury or certain medical conditions, like hydrocephalus.

Other symptoms of a CSF leak include:

If you suspect you may have a CSF leak, seek medical attention.

It may be difficult to tell the difference between a cold or other viral infection, and a bacterial infection. Color isn’t always the best indicator of whether you should see your doctor. Instead, pay attention to the duration of your illness and the worsening of your other symptoms.

Most colds last between 5 to 10 days. They usually peak in severity between days three and five. A bacterial infection may worsen as it progresses and continue beyond this time period.

Other signs you should make an appointment:

In rare cases, the infection may spread to the eye or brain. Seek medical attention immediately if you notice any of the following symptoms:

Think your snot may be the result of allergies? There are several things you can do to clear your congestion:

For congestion from colds and other conditions:

Alternatively, you may try using a neti pot to rinse debris or mucus from your nose. Be sure if you do, to use the neti pot prior to applying any nasal spray, such as Flonase. You can find neti pots online here.

To use a neti pot:

Snot is produced by your sinuses as protection against the outside world and its many viruses and other dangers. Most causes of congestion are due to viruses and allergies, not bacterial or fungal infections.

Unless you have an underlying medical condition, you may try at-home comfort measures to clear your congestion. If you notice warning signs of bacterial infection or have other concerns about your health, see your doctor.

Read this article in Spanish.

Last medically reviewed on March 2, 2022

Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.

Meredith Goodwin M.D., FAAFP

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