What Is the Difference Between Hyperaemia vs. Erythema?

Hyperaemia refers to the movement of blood into a tissue while erythema is sometimes a symptom of hyperaemia.

Hyperaemia is a broad medical term that describes the movement of blood into a tissue. The increased amount of blood causes swelling or congestion. Hyperaemia can have a variety of causes and reactions. 

Erythema is sometimes a symptom of hyperaemia, characterized by redness, swelling, and other less visible reactions. Erythema’s causes can range from massages to allergic reactions to medications. Symptoms of erythema can be short-lived or long-lasting.  

Symptoms of hyperaemia

Hyperaemia can occur both internally and externally. Hyperaemia is a physiological response, meaning it is a symptom itself. Usually, hyperaemia is a byproduct of a more extensive medical condition. 

Some symptoms of hyperaemia include: 

• Redness in the whites of the eyes
• Inflammation of the skin (red marks, red rings, or any form of redness)
• Eye congestion 
• Rashes
• Symptoms related to heart failure
• Swelling
• Itching
• Internal heat
• Sores
• Red bumps
• Blood clots

Symptoms of erythema

All the symptoms of hyperaemia can also be symptoms of erythema. However, there are some telltale signs that are specific to erythema. 

For example, rashes and skin redness caused by erythema will disappear when you apply pressure. Other types of rashes caused by hyperaemia remain red when pressure is applied.

Some common symptoms of erythema include:

• Itchiness
• Raised or round red bumps
• Sores 
• Red bull’s-eye rashes
• Large pink or red rashes
• General irritation of the skin
• Cold sores
• Fever
• Joint pain
• Filled lymph nodes

Hyperaemia has many causes. Some are minor, like sunburns, while others are more complicated, like heart failure. There are two different types of hyperaemia: active hyperaemia and passive hyperaemia. 

Active hyperaemia occurs when an increase of blood rushes to functional tissue. Erythema is a type of active hyperaemia. Some causes of active hyperaemia are:

• Exercise
• Eating
• Fever
• Inflammation
• Injury
• Hot weather
• Blockage of part of the body’s tissue
• Allergic reactions 
• Sunburn
• Massages
• Waxing
• Infections
• Acne

Passive hyperaemia occurs when blood flow in one part of the body is restricted. In these cases, the excess blood leads to hyperaemia. Examples of passive hyperaemia are:

• Heart failure
• Clotting in the lungs 
• Clotting in the liver

There are also two types of erythema: erythema multiforme and erythema nodosum.

Allergic reactions or sensitivities cause erythema multiforme. Erythema multiforme is always a sign of a broader health issue, never a diagnosis. Some of the allergies or infections that cause erythema multiforme are:

• Herpes simplex
• Steroids
• Antibiotics
• Certain types of barbiturates
• Anticonvulsants
• Skin infections
• Radiation

Erythema nodosum is also caused by certain infections, allergies, and sensitivities. However, its causes and symptoms are very different. 

The main signs of erythema nodosum are red bumps on the shins, fever, joint pain, and enlarged lymph nodes. Some causes of erythema nodosum are:

• Strep infections
• Tuberculosis
• Crohn’s disease
• Cancer
• Pregnancy
• Antibiotics 
• Iodides
• Contraceptives
• Bromides

Hyperaemia and erythema are closely related, and both conditions are a symptom of an underlying problem. Their treatment will therefore target the cause.  

In some cases, it will be clear whether you have erythema or another kind of hyperaemia. In other cases, your symptoms may be internal and not as visible. 

Some of the symptoms that suggest your hyperaemia is erythema are:

• Red bumps on the shins
• Sores on the mouth
• Large red rashes
• Itchiness
• Red bull’s-eye rashes
• Raised, round bumps
• Fevers
• Joint pain
• Congestion of the lymph nodes

There is no single treatment for hyperaemia or erythema. Both are natural responses to circumstances within or outside your body. 

Usually, hyperaemia and erythema are resolved by treating the broader issue that’s causing them. If your hyperaemia or erythema is related to an allergy or sensitivity, you should stop exposure to your allergens. 

Some of the outward symptoms of both hyperaemia and erythema can be very uncomfortable. If you have a rash, burn, or sore, there are many treatments that can ease the discomfort. 

If you notice rash, redness, soreness, swelling, or any other symptom that you can’t explain, you should seek medical care. These symptoms often mean that you’re experiencing irregular congestion or movement of the blood and should be examined.