In general, a red nose is caused by the body's reaction to something. What usually happens is that the body speeds up the heart rate and more blood is pumped to different areas of the body, such as the nose. The body can also redirect blood flow to certain areas if it feels the need. These bodily reactions are, in turn, triggered by some external and internal factors.
An external factor that causes redness of the nose is temperature. Especially during the winter, the cold temperature causes the body to conserve energy and heat by slowing blood flow. From time to time, the body opens the blood vessels and releases small streams of blood, causing the nose to turn red. In cases of frostbite, the body sends more blood to exposed areas, such as the nose, to warm them. If a person's nose becomes redder and more painful when touched, they should be transferred to a warmer, safer area and may need medical assistance.
Drinking alcoholic beverages can also cause a red nose. Too much alcohol in the body makes the blood vessels more vulnerable to rupture. The blood that flows from the broken vessels will then go to the surface of the skin, making the nose red. This is why a person who has had a drink to excess may have flushed cheeks to accompany their bright red nose.
Skin disorders like rosacea can also be a factor. Rosacea is a form of adult acne characterized by redness of the nose and cheeks, as well as small facial bumps that may contain pustules. If this condition becomes advanced, it can lead to rhinophyma, or a "bulb nose," in which the nose is so infected that it becomes red and inflamed. A fungal infection called seborrheic dermatitis can also cause this problem, along with itchy, flaky skin. These conditions may not be curable but can be treated with antibiotics or antifungal medications.
Redness of the nose can also accompany many illnesses, such as colds, flu, and allergies. A person tends to scratch the itchy nose or wipe away mucus, which makes the redness more noticeable. Sunburned people are also more likely to have a red nose, as the nose is one of the most exposed parts of the face. For a quick fix to a red nose, and the face in general, a person can splash ice water on their face to constrict blood vessels and reduce the appearance of redness.