Blood in snot can be caused by irritation or dryness of the nasal tissue, which may result from using nasal decongestants or inhaled drugs, as well as from conditions like allergic rhinitis, the flu, colds, or sinusitis.

Changes in weather or atmospheric pressure, as well as nasal surgery, can also lead to the presence of blood in nasal mucus.

When only a small amount of blood appears in snot, it’s usually not a cause for concern. However, if bleeding continues and doesn’t stop with pressure, it’s important to see a doctor for proper evaluation and treatment.

Main causes

Blood in your snot can be caused by:

1. Use of nasal decongestants

Frequent or prolonged use of nasal decongestants can cause blood in snot because these medications dry out and irritate the nasal lining, making it more likely to bleed.

What to do: use nasal decongestants only as directed by a doctor and for the recommended duration. As an alternative, saline solution can be used three times a day to clean the nose, or nasal irrigation can be done regularly throughout the day.

2. Allergic rhinitis

Allergic rhinitis causes the nasal lining to become inflamed and overly sensitive when exposed to substances like dust, pollen, or pet dander. This allergic reaction can trigger sneezing, runny nose, nasal itching, and sometimes blood in snot.

What to do: avoid exposure to allergens whenever possible. A doctor may prescribe antihistamines such as loratadine or cetirizine if needed. Natural remedies like inhaling eucalyptus steam or drinking peppermint tea may also help relieve symptoms.

3. Nosebleed (epistaxis)

A nosebleed, or epistaxis, occurs when small blood vessels in the nose rupture, leading to bleeding that may appear as blood in snot. It’s a common condition that is usually not serious but can be uncomfortable or alarming.

What to do: stay calm, tilt your head slightly forward, pinch the soft part of your nose between your thumb and index finger, and apply a cold towel or ice pack to the bridge of your nose.

4. Respiratory infections

Respiratory infections, such as the flu or a common cold, can cause sneezing, nasal discharge, and frequent nose blowing. These actions can irritate and inflame the nasal and sinus linings, resulting in blood in snot.

Fever can also dry out the nasal tissue and thicken mucus, making it easier for small blood vessels to rupture and bleed.

What to do: treatment should be guided by a healthcare provider, who may recommend medications like acetaminophen or ibuprofen to relieve symptoms. To ease congestion, you can do nasal rinses with warm salt water, use saline sprays, inhale steam, and drink 2 to 3 liters of water daily.

5. Dry weather and pressure changes

Dry climates, low humidity, or sudden changes in air pressure—such as during flights, mountain climbing, or diving—can cause blood in snot or even nosebleeds.

Dry air can make the nasal lining crack and form crusts, which may bleed easily when rubbed or blown. Pressure changes can also irritate the sinus lining when pressure isn’t equalized properly.

What to do: keep indoor air humid by opening windows or using a humidifier. Avoid diving if you have a cold or active allergic rhinitis.

If nosebleeds happen frequently, a doctor may prescribe nasal sprays such as oxymetazoline or glucocorticoids, which should only be used under medical supervision.

6. Sinusitis

Sinusitis is inflammation of the sinus cavities, which can cause nasal congestion, facial pain, headaches, and nasal discharge. Because the lining becomes inflamed and swollen, small blood vessels may rupture, leading to blood in snot. Sinusitis can be caused by bacteria, viruses, fungi, or allergies.

What to do: to relieve symptoms, do nasal rinses with saline, inhale warm steam from the shower, and avoid staying in poorly ventilated spaces. The treatment depends on the cause, so it’s important to see a doctor or ENT specialist for proper evaluation and guidance.

7. Inhaled drugs or chemical irritants

Inhaling drugs such as cocaine or poppers, or being frequently exposed to cleaning products or chemical vapors, can cause blood in snot and, in severe cases, nosebleeds.

These substances irritate and dry the nasal lining and constrict blood vessels, making bleeding more likely when the nose is touched or blown.

What to do: stop using the substance or avoid areas where chemical vapors are present. Do not blow or touch your nose forcefully, as it can worsen bleeding.

If a nosebleed occurs, tilt your head forward and apply pressure to the soft part of your nose for 10 to 15 minutes. If bleeding does not stop, seek medical attention right away.

8. After nasal surgery

After nasal surgery, it’s common to notice blood in snot due to irritation and inflammation caused by tissue manipulation during the procedure. Blood clots may also form during healing and mix with mucus, giving it a bloody appearance.

What to do: follow all postoperative instructions provided by your surgeon, including how to clean the nose with saline solution and use any prescribed sprays or medications. Avoid blowing your nose forcefully or engaging in strenuous activities that increase pressure in the nasal area, such as lifting heavy objects.

Keep your head elevated while resting to reduce congestion and bleeding, and drink plenty of water to stay hydrated and prevent dryness in the nasal passages.

9. Use of anticoagulants

Blood-thinning medications like warfarin or heparin can increase the risk of bleeding, which may lead to blood in snot if the nasal tissue becomes irritated.

What to do: if there is only a small amount of blood, it’s usually not a concern. However, if the bleeding is heavy or persistent, contact your doctor to check whether medication adjustments are necessary.

10. COPD (chronic obstructive pulmonary disease)

Chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis, can occasionally cause blood in snot due to airway irritation or secondary infections. While it’s not a common symptom, it can happen in some cases.

What to do: see a pulmonologist, especially if this is the first time you notice blood in snot or if the amount is significant. The doctor will evaluate your condition, identify the cause, and recommend the most suitable treatment.

When to see a doctor

You should see a general practitioner, pulmonologist, or ENT specialist if:

The blood in snot or nosebleed does not stop after gentle pressure
You experience frequent bleeding after nasal surgery
There is severe pain along with the blood in snot or nosebleed

If other symptoms appear, such as fever, foul-smelling nasal discharge, shortness of breath, or vision changes, you are advised to seek immediate medical attention.