Serous Drainage

Serous drainage is a clear to yellow fluid that leaks out of a wound. It’s slightly thicker than water. It’s the fluid that makes your bandage look and feel wet. This type of wound drainage is a normal part of your body’s healing process. Too much serous fluid is a sign of an infection.


An illustration of three wound dressings with serous drainage and other types of exudate.
Serous drainage is one of three types of exudate (wound drainage).

What is serous drainage?

Serous drainage, or blood serum, is a type of fluid that comes out of a wound with tissue damage. It’s normal for your wound to leak small amounts of this clear fluid. However, if you notice your wound drains a lot of fluid, or if the fluid draining is thick like pus, contact a healthcare provider. A lot of serous fluid or pus leaking from the wound can indicate the presence of a bacterial infection.


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What does serous drainage look like?

Serous drainage is a clear to yellow fluid. The texture of serous drainage is slightly thicker than water. When you remove the bandage that covers your wound, you may see a wet outline in the gauze of your bandage.

What makes up serous drainage?

Serous drainage is plasma without proteins. Plasma is the liquid base of blood. Plasma is over 90% water and less than 10% solids. The solids include proteins like fibrinogen, which is a protein that your liver makes to help with blood clotting.

When you get a wound and start to bleed, blood proteins stop below the surface of your skin at the wound to limit bleeding by coagulating. During coagulation, your proteins change your liquid blood into a semisolid state. This process prevents you from losing too much blood. As a result, liquid plasma (without proteins) moves to the surface of the wound while the proteins stay behind.


Why do I have serous drainage?

Serous drainage is a sign that your immune system is working correctly to heal a wound. Serous drainage is normal in small amounts. Large amounts of serous drainage can be a sign of an infection, so reach out to a healthcare provider if you have a lot of wound drainage.

What are the different types of wound fluids?

There are three different types of fluid in addition to blood that come from a wound, including:

  • Serous drainage: Serous drainage is a clear to yellow fluid that’s a little bit thicker than water. Serous drainage is normal and it’s a sign that your body is healing.
  • Serosanguinous fluid: Serosanguinous fluid is a combination of serous fluid and blood. It’s usually a light pink to red color. This is a sign that your body is healing the wound and isn’t a concern in normal amounts.
  • Purulent drainage: Purulent drainage, the thickest of the three types, is white, yellow or brown fluid. It indicates that bacteria entered your wound and caused an infection. Infections can be harmful to your body, so this fluid needs treatment. It may have an unpleasant odor.

Possible Causes

What causes serous drainage?

Serous drainage occurs when your body heals a wound. It’s important for your body to direct blood and other body fluids to the site of a wound to start the healing process. Your immune system starts the process of inflammation, which sends components of your immune system to the wound to destroy invaders like bacteria that can make you sick. The process of bringing fluids to the site of a wound causes it to have serous drainage. You may also have serous drainage if you have a significant amount of swelling beneath your skin.

There are three types of wounds that can cause serous drainage, including:

  • An open sore: An open sore is the most common type of wound caused by tissue damage in your skin.
  • Venous ulceration: This type of wound occurs when the veins in your legs aren’t able to push blood back up toward your heart as well as they should and your legs swell. The poor blood flow and excess swelling break down the skin barrier and can cause an ulcer.
  • A partial-thickness wound: A partial-thickness wound is a break in the layers of your skin that doesn’t reach below the dermis (the second layer of your skin).

You may also have serous drainage after surgery.

Care and Treatment

How do I stop serous drainage?

Serous drainage will stop on its own as your wound heals. Treating your wound helps serous drainage go away and can help prevent infection. To take care of your wound, you should:

  • Wash the wound gently with soap and water. Pat the wound area dry.
  • Cover the wound in a bandage or wound dressing. You might want to apply a topical antibiotic to your wound to prevent infection.
  • Change the bandage over your wound daily or as directed.

Follow a healthcare provider’s instructions if they mention a specific way that you need to take care of your wound.

In most cases, repeated use of alcohol or hydrogen peroxide can lengthen your healing process or prevent a wound from healing properly. Ask your healthcare provider what you should apply to your wound.

Is serous drainage dangerous?

No. Serous drainage isn’t dangerous when it occurs in small amounts in your bandage. This is a normal process of how your body heals. Contact a healthcare provider if you notice your wound leaks a large amount of fluid or if your bandages seem to be soaked with fluid when you change them.

When To Call the Doctor

When should a healthcare provider treat serous drainage?

Visit a healthcare provider if:

  • You have a wound that won’t heal.
  • Your wound leaks a lot of fluid.
  • Yellow or white pus or a cloudy fluid leaks from the wound.
  • You experience severe pain or swelling.
  • You experience fevers or chills.
  • Redness around your wound is spreading or getting larger.

A note from Cleveland Clinic

You don’t need to worry about serous fluid since it’s a normal part of how your body heals itself. When you have a small wound, you can take care of it at home by cleaning your wound and applying a new bandage at least once per day. If you experience soggy bandages that need changing frequently or you have severe pain or swelling at the site of your wound, visit a healthcare provider.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 05/30/2023.

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