Skin color is determined by several factors, such as the amount of natural pigment (melanin) and blood flow under the skin. Variations of these two main factors are responsible for the range of colors that are seen in the human race. While we all expect to see varying degrees of brown and red, there are instances where the skin may turn blue. Usually it is a serious sign of insufficient oxygen in the body and always requires immediate medical attention. However, there are instances where a bluish tinge may be due to environmental factors or only occurs momentarily due to a disturbance with blood flow through some part of the body.
When is blue skin a dangerous sign?
Contact with blue substances can tint the skin blue for a period of time. For example, contact with food coloring agents that have a strong blue color or with dyes and ink can turn the skin blue. Since the hands are the main way that we make physical contact with the environment without any covering (for most people), it is highly prone to become tinged with strongly colored agents in the environment. This is obviously not a danger unless the substance that made contact with the skin is toxic.
The other major reason why skin turns blue in color is due to changes in the blood oxygen levels. Blood is a bright red color when it has sufficient oxygen, as a result of oxgen binding with hemoglobin. The red that we see is due to blood reflecting red light and absorbing other color of the spectrum. When oxygen levels are low and carbon dioxide levels rise the change in blood chemistry cause it to have a blue tinge. However, this does not mean that the blood is blue in color. It is still red, albeit a different shade, but now reflects some blue light as well.
If the bluish color of skin is due to this change in blood oxygen levels then it is considered to be dangerous. The body needs oxygen to survive and insufficient oxygen leads to tissue injury (ischemia) and even tissue death. When the heart or brain tissue dies, the consequences can be very serious and even life-threatening. However, even tissue death in the extremities like the fingers can be dangerous although not usually life-threatening.
Causes of Blue Discoloration on the Hands
The tips of the extremities are often more likely to turn blue faster than the torso or head. This is due to the fact that the blood has to travel further to reach the ends of the extremities, such as the fingers and hands of the upper limb. Oxygen may therefore be utilized before it can reach the ends although this does not explain every case of blue discoloration of the hands and fingers.
Inks, Dyes and Colorants
There are many substances in our daily environment that can tint the skin. Ink is one such example and is a substance that most of us are exposed to when using a pen. Dyes and food coloring agents can also color the skin blue but this is more likely to occur with people who are exposed to these substances, like in the workplace. Sometimes more than two or more chemicals may interact on the skin to yield a blue color although a person cannot recall touching anything with a strong blue color.
Certain climatic conditions can also cause blueness of the skin, even in a healthy person. Extreme cold is one example. It causes the tiny blood vessels in the skin to constrict (narrow) as a way of conserving temperature. This reduces blood flow to the skin surface and this cause the area to become pale and even blue in color. High altitudes can have the same effect due to the cold but also due to the low oxygen levels in these areas.
Disruptions in blood flow can prevent oxygen-rich blood from reaching a part of the body or for blood low in oxygen from leaving an area and returning to the heart. In this way oxygen cannot reach a part of the body and carbon diocide accumulates. As a result it may cause the area to appear blue in color. This may include conditions such as:
- Peripheral arterial disease
- Raynaud’s phenomenon
- Anemia and other disorders that affect the oxygen-carrying capacity of blood.
- Blood clots
- External compression like with tourniquets.
The heart is responsible for circulating blood. It receives low oxygen blood and sends it to the lungs for oxygenation. The oxygen-rich blood returns to the heart and is then pumped to the entire body. If the heart is malfunctioning then the blood cannot be distributed as normal and blood may not be able to be properly oxygenated.
This can happen with a range of different cardiac diseases, such as heart failure, myocardial infarction (heart attack) and cardiomyopathy. It may also occur with heart valve disease and congenital heart defects, particularly a group of conditions known as cyanotic heart disease.
Read more on heart diseases.
Lung and Airway Disease
The airways and lungs are responsible for delivering oxygen into the bloodstream and removing carbon dioxide which is then passed out into the environment. Diseases of the lungs and airways can therefore lead to a low blood oxygen levels and/or a build up of carbon dioxide in the system. This may be seen with conditions such as:
- Chronic obstructive pulmonary disease (COPD)
- Infections of the airway (laryngitis, tracheitis or bronchitis) or lungs (pneumonia)
- Pneumonitis (allergic)
Drugs, Poisons and Toxins
A number of different chemicals can affect the blood oxygen levels, circulation of blood or functioning of the lungs. This can occur with pharmaceutical drugs, but usually with an overdose. Poisons may have a similar effect and can include synthetic substances like arsenic or natural substances like the toxins in certain poisonous fish. Venom is another toxin which is delivered by an animal or insect into the skin. Sometimes these toxins are not always obvious, like when in contaminated water, and only has an effect after long term consumption.