How does clotted blood look? A visual guide to different types

September 27, 2025 •

4 min read

According to the CDC, up to 900,000 Americans are affected by blood clots each year. Understanding how does clotted blood look is crucial for recognizing a potential health threat and knowing when to seek immediate medical attention.

Quick Summary

Clotted blood appears as a dark, semi-solid, and sometimes jelly-like mass, with colors ranging from deep red to black, depending on its location and age. The texture and presentation vary significantly between an external wound and a potentially dangerous internal thrombosis.

Key Points

External vs. Internal: External clots are visible on wounds or during menstruation and are part of the body's natural healing. Internal clots form inside blood vessels and are often invisible, with symptoms like swelling or pain being the only signs.
Color and Age: The color of clotted blood can indicate its age; brighter red means it's fresh, while darker red, brown, or black indicates older, oxidized blood.
Normal Menstrual Clots: Small, infrequent menstrual clots are normal, but very large or frequent ones warrant a medical consultation.
DVT Symptoms: Look for symptoms of deep vein thrombosis (DVT) like unexplained swelling, pain, redness, or warmth in one limb, especially the leg.
Emergency Signs: Sudden shortness of breath or chest pain could indicate a pulmonary embolism (PE), a serious complication of a blood clot that requires immediate emergency care.
Medical Imaging: The only way to truly see an internal blood clot is through medical imaging techniques like an ultrasound, not visual inspection of the skin.

The Basics of Blood Clotting

Blood clotting, or coagulation, is a vital process that prevents excessive bleeding when a blood vessel is damaged. Platelets and proteins in the blood plasma work together to form a clot at the site of injury. This is a normal, healthy function. However, when clots form inside veins or arteries without a clear purpose, they can become a serious medical issue, blocking blood flow and potentially dislodging to travel to the lungs or brain. Therefore, understanding the appearance of a blood clot is essential for your safety.

External Blood Clots vs. Internal Clots

It is important to differentiate between visible external clots and those that form internally.

External Blood Clots

These are the clots you see on the surface of a wound, such as a scrape or cut, or during menstruation. Their appearance varies based on freshness and exposure to air:

Fresh clots: Often appear as a reddish-jelly-like substance at the wound site. They are made of platelets and fibrin, which trap red blood cells.
Older clots (scabs): As the wound heals, the clot dries and hardens, forming a dark, crusty scab. These are typically black or dark brown in color.
Menstrual clots: These are common during heavy periods and are usually dark red, brown, or black and can range in size. They are a combination of blood, tissue, and mucus. Small, infrequent menstrual clots are generally not a concern, but large clots (bigger than a quarter) or an increase in their frequency should be discussed with a doctor.

Internal Blood Clots

Internal clots, or thrombi, form inside the blood vessels. They are not visible on the surface of the skin, though they may cause visible symptoms. Their appearance is only seen via medical imaging. What you will see are the effects they have on the surrounding tissue.

Deep Vein Thrombosis (DVT): A clot that forms in a deep vein, most often in the leg. Symptoms include redness or a bluish discoloration of the skin, swelling, pain, tenderness, and warmth in the affected limb. The skin might look discolored, but you won't see the actual clot.
Pulmonary Embolism (PE): Occurs when a DVT breaks loose and travels to the lungs. It is a medical emergency. You cannot see the clot, but symptoms include sudden shortness of breath, sharp chest pain, and coughing up blood.
Heart Attack/Stroke: Clots blocking blood flow to the heart or brain are critical. Visual signs might include a pale or bluish appearance of the skin (especially lips), or a visible change in facial expression and mobility due to a stroke.

The Spectrum of Color and Texture in Clotted Blood

The color and texture of a blood clot can provide clues, especially with external wounds or menstrual bleeding. The variation is primarily due to the blood's age and oxygen exposure.

Bright Red: This indicates fresh blood that has clotted almost immediately after exiting the body. It is often thick and gelatinous.
Dark Red/Maroon: Clots that are a few hours old will appear darker. This is a very common color for menstrual clots.
Brownish/Black: This coloration signifies older blood. As blood ages and is exposed to oxygen, it oxidizes and darkens. Scabs are a prime example.
White: Rarely, a clot may appear whitish. This can be caused by a platelet-rich, red blood cell-poor clot. These are less common but can occur in certain conditions.

A Comparison of Different Types of Clots


Feature	External Clots (e.g., Scab, Menstrual)	Internal Clots (e.g., DVT)
Visual Appearance	Visible on the skin's surface or discharged from the body. Can be jelly-like, crusty, or brownish.	Not visible from the outside. Signs include swelling, redness, and discoloration.
Location	On a wound, cut, or from the uterus during menstruation.	Inside a deep vein, most commonly in the leg, but can be anywhere.
Symptoms	Bleeding stops, wound heals. Minimal pain.	Pain, tenderness, swelling, warmth, and skin discoloration.
Risk Level	Normal and protective function of the body.	High risk, can be life-threatening if it moves.
Resolution	Dissolves on its own as the wound heals.	Requires medical treatment, such as blood thinners.

When to Seek Medical Attention

While the sight of a normal, protective external clot is not a cause for concern, recognizing the warning signs of an internal clot is essential. Do not attempt to self-diagnose by searching online images; instead, focus on the symptoms. It's always better to be cautious.

For External Wounds: If bleeding does not stop after applying pressure for a few minutes, or if the wound shows signs of infection like pus or severe swelling, seek medical help.
For Menstrual Clots: If you pass large clots (bigger than a quarter) regularly, experience very heavy bleeding (soaking through a pad or tampon in less than two hours), or have severe pain, consult a healthcare provider.
For Internal Clot Symptoms: If you experience any symptoms of a DVT (swelling, pain, redness in a leg) or a PE (chest pain, shortness of breath), seek emergency medical care immediately. A stroke requires immediate emergency attention.

Conclusion: How Does Clotted Blood Look? Summary

In conclusion, the appearance of clotted blood is not a single, universal image. It varies widely based on whether the clot is external or internal, fresh or old, and the specific circumstances. While external clots are a sign of the body's natural healing process, internal clots can be dangerous and require immediate medical intervention. Awareness of the signs and symptoms is more important than the visual appearance of the clot itself. For more information on blood clots and prevention, consider visiting the National Blood Clot Alliance. If you have concerns about any symptoms, speaking to a medical professional is always the right course of action.

Frequently Asked Questions

In a wound, a fresh blood clot typically looks like a dark, red jelly-like clump. As it dries and hardens to form a scab, its color will turn dark brown or black and its texture will become crusty.

The color of a blood clot itself does not necessarily indicate its danger. Dangerous internal blood clots (like DVT) are not visible on the skin's surface. What's more important are the accompanying symptoms, such as swelling, redness, and pain in the affected area.

Menstrual clots can look like small or large clumps of blood and tissue. They are commonly dark red, brown, or black. While small clots are normal, large clots (bigger than a quarter) can be a sign of a medical issue.

No, you cannot see a deep vein thrombosis (DVT) directly in your leg. Instead, you would see the symptoms it causes, such as swelling, redness, warmth, or a bluish discoloration of the skin in the affected area.

A bruise (or hematoma) typically starts as a red area that turns blue, black, and eventually yellow/green as it heals. It is usually flat. A dangerous blood clot, especially DVT, often causes swelling, is warm to the touch, and can cause significant pain, which a simple bruise does not.

Black coloration in clotted blood, such as in a scab or menstrual clot, typically indicates that the blood has oxidized and is older. In external bleeding, black clots are generally a sign that healing is progressing and the blood is no longer fresh.

Blood clots in stool can appear as maroon or black clumps, or as streaks of bright red blood. This can indicate bleeding in the gastrointestinal tract and should be evaluated by a doctor immediately.