The biggest factors impacting the color of pus are what the it is made of, particularly where proteins and enzymes are concerned, and why it was created in the first place — which is to say, what sort of disease or condition it’s meant to be fighting. Pus is a thick liquid that humans and many animals produce in response to infection. It is usually white, clear, or yellowish in color, but in some cases it may also appear red, green, or brown. In very rare cases it can also be blue, but this is usually a reaction to only a very few number of pathogens or harmful cells. Color can say a lot about a person’s health and the state of his or her injury, and most medical professionals use the color of pus that is oozing from a wound or internal injury to help make a diagnosis. As such, anyone who is concerned about the colors they see should probably get medical help in order to get to the root of the issue.
Basics of Pus
There are a couple of different reasons why the body produces pus, but almost all of them have to do with infection. The liquid typically pools around the site of an injury or damaged tissue in order to flush out some of the most harmful bacteria. It’s part of the body’s immune defense and its main goal is to help remove diseased or infected cells and other particles. It’s made primarily of neutrophils, which are white blood cells.
The color of pus is largely dependent on where the injury is, what sort of infection is involved, and how long the infection has been going on. Though pus is an important part of the immune response, it is also usually a sign that something is wrong. Color can be a good indication of what, exactly, is amiss, which in turn can lead to more effective treatments and faster healing times.
White and Yellow Varieties
It’s usually considered “normal” for the body to create white, yellow, or clear pus, though this is usually because these are the colors that come about in response to so-called “common bacteria.” This includes Streptococcus pyogenes and Staphylococcus aureus. These strains are responsible for dozens of different infections, ranging from minor skin conditions like pimples to deadly diseases like meningitis.
Simply being common doesn’t make light-colored pus something that should be ignored, though. There are many potentially serious reasons why white, yellow, or clear fluid may be leaking from a wound, and for this reason the condition should often be investigated by a medical professional. Depending on the amount of pus and severity of the condition, antibiotics might be recommended to help fight the underlying infection.
Reddish Tints
Pus can also take on a reddish color. Red pus is usually due to blood mixing with the pus cells. This frequently occurs in urinary tract infections as well as certain skin infections like pimples and boils. The presence of blood does not necessarily mean that the body is having trouble fighting the infection; rather, it more commonly signals that the skin or other bodily tissues have become very irritated.
Green Hues
Green is another common color of pus and might mean one of two things. This pus may be caused by Corynebacterium diphtheriae, which is an uncommon infection of the upper respiratory tract. Pus can also get a green coloring from an antibacterial protein called myeloperoxidase. This brightly colored protein is naturally produced by certain types of white blood cells.
Brown Coloring
Brown pus is usually a sign of an amoebic liver abscess, which is caused by the parasite Entamoeba histolytica. Symptoms of an amoebic liver abscess include abdominal pain, fever, chills, diarrhea, jaundice, joint pain and weight loss. If left untreated, these abscesses can burst and spread the infection to the lungs, brain and heart.
Rare Blue Shades
Blue pus is usually considered very rare, and is the least common of all the different types. This color typically indicates an infection caused by Pseudomonas aeruginosa, which most often infects the urinary tract, pulmonary tract, lungs, kidneys, and blood. Burn wounds are especially vulnerable to Pseudomonas aeruginosa. If left untreated, these infections can become fatal.
Importance of Medical Help
Regardless of its color, pus is not always visible. While it is most commonly associated with open wounds, it can also be found inside the body. Symptoms of pus inside the body, which is also called an abscess, include swelling, heat, pain, redness and compromised function in the area. Many abscesses will not heal on their own, which means that patients should seek professional medical treatment once they notice that something is wrong in order to improve their condition. Pus is the body’s way of protecting itself, but it is also a warning sign that modern medical practitioners can translate and, in most cases, reverse.
Is Yellow Pus a Sign of Infection?
All pus, regardless of color, is a sign of infection. However, not all pus is a cause for concern. For example, most pimples develop a buildup of pus towards their center, which usually appears white in color. However, most pus is actually whitish-yellow upon closer investigation. Either way, pus-filled pimples are a normal skin condition that is rarely a cause for concern beyond aesthetic preferences.
In other situations, pus is a problem because of where it is located and how much is present. Yellow pus that occurs in the mouth, around an injury, or at an incision or injection site usually requires medical treatment. Pus can also develop internally, whether deep under the skin or around organs and tissues. In these circumstances, the patient is unable to detect the pus, but will often see a physician because of other symptoms, such as fever, swelling, pain, difficulty breathing, or other health issues.
What Color Pus Is Bad?
Pus that is white, yellow, or clear in appearance is common and is a normal reaction to typical skin conditions and minor injuries. It is also normal to see pus of a pink or reddish hue because it signifies the presence of blood in the area, which is not uncommon. Be wary of pus with these hues that are:
- Prolific
- Unusual
- Chronic
- Foul-smelling
- Accompanied by other signs of infection
Pus that demonstrates these symptoms is almost always serious and should be evaluated right away by a medical professional. In fact, it is always a good idea to call your doctor if you notice anything other than minor pimple pus on your body, just to be safe.
Pus that has a blue, brown, or green color is not normal and requires immediate medical attention. These colors often signify the presence of dangerous bacteria, infections, or parasites and should be evaluated as soon as possible. Infections and pus buildup can lead to sepsis, which can be fatal when left untreated. Fortunately, most of these issues are treatable when caught early enough.
Clear Pus VS White Pus
You may notice a clear fluid that drains from pimples, minor injuries, or wounds from time to time. While many people assume this is a type of pus, it is actually known as serous fluid and it's a good sign in many situations. This type of drainage occurs when the area is still very inflamed, but infection is not currently present. As long as the drainage is not profuse and stays clear or slightly tinged with blood, there is no cause for concern. It should also improve over time.
Fluid that has built up an accumulation of dead white blood cells, along with bacteria and damaged tissues, will turn white. This is technically pus and only occurs when an infection is present. However, you may notice both pus and serous fluid in some situations. Keep in mind that while some serous fluid exiting through the skin is normal, a buildup of this substance is not. This leads to swelling and can be a sign of serious conditions that require prompt medical treatment.