What Causes Unexplained Bruising and When to Seek Care

Packages arrive, and you bring them inside. A day later, a deep purple bruise appears on the inside of your upper arm. You don’t know how you got it.

You’re walking back into the house and stub your toe on the patio door frame. A day later, the end of your toe is bruised. It makes no sense to you, as you had shoes on and didn’t feel that you kicked it that hard. What’s going on?

A bruise is an area of skin discoloration that’s larger than a centimeter. It’s caused by damage to the capillaries, or tiny blood vessels, that are just under the skin. When they’re damaged, they leak blood into the tissue, causing the dark purple, blue, red, and black coloring you frequently see.

Most bruises are harmless and go away with time. However, frequent or unexpected bruising can indicate an underlying health condition, malnutrition, or drug interaction. When bruises are tied to issues like those, it’s important to seek care.

Understanding Bruises

When capillaries break when your skin comes into contact with something else, the body’s clotting system seals the break. A normal bruise lines up with the area of impact. You dropped a reusable water bottle on the top of your foot. A bruise appears on the top of your foot. That’s normal. 

Abnormal bruising usually appears spontaneously. You don’t remember bumping into anything, or it appears in unusual areas. For example, you wake up and find a bruise on your stomach. You have no idea why.

Three Levels of Bruising

Most bruises you see are subcutaneous bruises. They occur when blood pools under the skin and may be normal or unexplained.

 Intramuscular bruises occur within muscle tissue. A blow or fall impacts the muscle fibers and causes bleeding within the muscle. If you have an intramuscular bruise, you may not see a bruise forming immediately. It can take a few days. Other symptoms include swelling, muscle stiffness, and lumps.

The third type is a periosteal bruise that occurs on the outer layer of a bone. These bruises may not be visible, but a painful bump or swelling often appears in the injured area.

The Lifecycle of a Bruise’s Coloring

When you first get a bruise, it’s often red because oxygen-rich blood pools under the skin’s surface. It may develop into a more purple, blue, or black tone within a couple of days as the blood loses oxygen. 

By the end of the week, a bruise may gain a yellow or green tinge from bilirubin or biliverdin produced as the body breaks down any remaining hemoglobin. It continues to fade and should be gone within two weeks.

Common Causes of Unexplained Bruising

While a normal bruise appears after a fall, blood draw, or collision, unexplained bruises usually have an underlying cause.

Physiological Causes

Age and genetics may play a role in your unexplained bleeding.

• Aging: Thinner skin and loss of subcutaneous fat weaken the support for your capillaries.
• Genetics: Women often have thinner skin and different fat distribution than men, which makes them more likely to bruise easily. Women also experience monthly periods, which can deplete iron levels.

Medications and Supplements

Some medications and high doses of over-the-counter supplements can cause bruising because they thin the blood or skin tissue. These medications include: 

• Aspirin
• Blood thinners
• Corticosteroids
• Fish oil
• Garlic
• Ginkgo biloba
• NSAIDs
• Topical steroids
• Vitamin E

Nutritional Deficiencies

Malnutrition can also cause unexplained bruising.

• Iron: Most people get enough iron in their diet, but women have a higher risk of anemia, especially if they have heavy periods and don’t eat enough iron-rich foods.
• Vitamin C (Scurvy): Vitamin C is essential for blood vessel strength and collagen synthesis.
• Vitamin K: Vitamin K helps synthesize blood-clotting factors in the liver.

Underlying Medical Conditions

Unexpected bruising is also linked to underlying health conditions.

• Clotting Disorders: Conditions like Hemophilia, Idiopathic Thrombocytopenic Purpura (ITP), or Von Willebrand Disease impact your blood’s ability to clot.
• Liver Disease: If your liver isn’t working properly, it impacts the production of clotting proteins. Your blood needs extra time to form a clot.
• Serious Hematologic Issues: Certain blood cancers, such as leukemia, or bone marrow conditions or blood cancers suppress production of healthy platelets.

Bruising Red Flags: When to See a Doctor

You’ve noticed a bruise and don’t remember doing anything that would have caused it. When should you see a doctor, and how urgent is it?

	Key Symptoms	Where to Go
Non-Urgent Care	It’s been two weeks, and the bruise hasn’t faded. You started a new medication and noticed bruising.	Schedule an appointment with your Primary Care Physician (PCP), if you have one.
Urgent Care	Bruises accompany other symptoms like bleeding gums, exhaustion, frequent nosebleeds, or heavy periods. Large, unexplained bruises appear on your back, face, or trunk. You don’t have a PCP and have had a bruise for more than two weeks. You find small pinpoint brown, purple, or red spots (petechiae) that aren’t fading in a few days.	Go to urgent care in the next day or two.
Emergency Care	Bruises accompany extreme tightness, severe pain, or swelling. You experienced head trauma and see bruising. You’re not only bruising, but you’re finding blood after going to the bathroom, coughing up blood, or suddenly feeling weak.	Go straight to urgent care or the emergency department.

What to Expect During a Doctor’s Visit

When you go to urgent care, your doctor may never have met you before. A quick review of your medical history is important.

Health History

Share any medications you take (both over-the-counter medications and nutritional supplements) and all prescriptions. If possible, take a photo of the label so that the doctor can review the strength and dosing information.

A family history is important. If your mom was anemic, it’s important for the doctor, as there could be a genetic link. Your grandfather might have had a clotting disorder, which is also vital information when it comes to diagnosing the cause of your bruising.

Your doctor will look at your skin. As you age, subcutaneous fat diminishes. Collagen production slows. Your skin often becomes thin and even crepey, and thin skin bruises easily. 

Finally, expect your doctor to check your lymph nodes for swelling, your liver and spleen for tenderness, and the size, location, and shape of your bruise. This helps pinpoint possible health concerns.

Blood Tests

A Complete Blood Count (CBC) checks your platelet levels. It also provides information like your iron levels, which can indicate anemia.

If iron counts are low, doctors may also order tests for your Total Iron Binding Capacity (TIBC) and vitamins like B12 and folate.

Coagulation Panels look at how quickly your blood clots. If blood clots too slowly, bruising is more likely. They can also point doctors to bleeding disorders. 

If bruises persist or come with other symptoms like fatigue or unexplained bleeding, a doctor can determine what’s happening. The right treatment plan helps protect your health and prevent it from worsening.

 Premium Urgent Care’s doctors are here throughout the week and on weekends for walk-in care. We do blood draws on-site, so you don’t need to go to a second location for tests. Check in online and see a doctor without waiting weeks or months for an appointment.