5 reasons you keep getting those mysterious bruises

• Bruising easily is often the result of taking blood-thinning medications, including ibuprofen.
• Other medications that can lead to more bruises are steroids like Prednisone and Hydrocortisone.
• Having a deficiency in vitamin C or K may also cause easy bruising.

If you get large, dark bruises from small bangs or bumps, or seem to get bruises for no reason, this may be a sign that you bruise more easily than normal.

Most of the time bruises are normal and nothing to worry about. But if you bruise extremely easily or get bruises without any injury, this can be a sign of a serious issue like a vitamin deficiency or blood clotting disorder.

Here are five reasons why you may be bruising easily and when you should see a doctor.

1. You take blood-thinning medications

Blood-thinning medications help protect you from heart attacks and strokes by preventing blood clots. But clotting actually helps keep bruises under control.

Bruises happen when something like a bump damages the small blood vessels right under the surface of the skin. The blood vessels leak, creating a purplish welt. Normally, your blood will clot quickly, stopping the blood vessels from leaking and preventing extreme bruising.

But if you take blood thinners, your blood won't clot as easily or quickly. This allows for more blood to leak out, making it appear as if you have larger, more severe bruises.

Some of the most common blood-thinning medications include:

• "Aspirin and Plavix (clopidogrel) are antiplatelet medications most often to blame for easy bruising," says Sharon Orrange, MD, a professor at the University of Southern California's Keck School of Medicine.
• Blood thinners like Coumadin (Warfarin) and Lovenox (Enoxaparin) can also cause easy bruising.
• Novel oral anticoagulants, like Xareltro Eliquis, and Pradaxa
• Non-steroidal anti-inflammatory drugs like Ibuprofen may also inhibit clotting, Orrange says.

Important: You shouldn't stop taking blood thinners just because you bruise easily - talk to your doctor about your options to address the problem.

2. You have a vitamin deficiency

Having low levels of the following vitamins can make it harder for your blood to clot correctly, which causes more bruising:

• Vitamin K: Your body needs vitamin K to form the proteins that allow blood to clot normally and stop bleeding. Having too little vitamin K can cause easy bruising as well as more serious symptoms like blood in your urine or stool.

• Vitamin C: Vitamin C helps your body form collagen, which creates the structure of your blood vessels. Too little vitamin C can make your blood vessels more likely to damage and cause bruising. Vitamin C deficiency can also cause fatigue and depression.

3. You take steroid medications

Since steroid medications fight inflammation, your doctor may prescribe you some if you have an inflammatory condition like arthritis or lupus.

But steroids can also have side effects for your skin:"Steroids such as Prednisone and Hydrocortisone cause thin skin and lead to easy bruising," Orrange says. This is true whether you take steroids as a pill or as a topical cream.

Thinner skin means the blood vessels under your skin's surface may be more likely to be damaged, leading to bruising.

4. You have a blood clotting disorder

Certain diseases can make it harder for your blood to clot, leading to excessive bleeding and bruising from injuries.

• Von Willebrand disease is a genetic disorder in which you have too little of the protein that help your blood clot. The disease can also cause nosebleeds and heavy menstrual bleeding.
• Hemophilia is another genetic condition that makes it harder for your body to clot normally. Along with easy bruising, hemophilia can cause symptoms like bleeding of the mouth and gums or bleeding after getting shots.
• Platelet function defects are conditions in which your platelets don't work properly, leading to excessive bleeding and bruising.

5. You're over 75

As you age, your body produces less collagen and elastin proteins, which are important for the structure of your skin. Losing these proteins makes the skin less resistant to pressure and friction, Orrange says.

Your skin also gets thinner as you age, which means your blood vessels have less protection and you're more likely to bruise, Orrange says.

"These changes are more significant in those over 75 years of age," Orrange says.

When to see your doctor

Though most bruising is normal, Orrange says the following signs may be an indication that something more serious is going on:

1. You develop bruises without any injuries or get severe bruises from minor hurts.
2. Bruising on your arms or legs is more common, while bruises on other areas like your abdomen may be a sign of a disease like pancreatitis.
3. You're getting bruises all over. "Easy bruising we worry about usually occurs on multiple areas of the body," Orrange says.
4. Along with bruising, you have a history of bleeding after invasive procedures or surgery, including dental work.

If you have any of these signs, or your bruising seems abnormal for other reasons, talk to your doctor about what the cause might be.

Insider's takeaway

Bruises are part of your body's normal reaction to getting injured, but bruising too easily can be a cause for concern. In some cases, excessive bruising can be linked to a dangerous vitamin deficiency or a blood clotting disorder.

As a general rule, you should reach out to your doctor "if you notice five or more bruises greater than 1 cm (the width of an average fingernail) in diameter," Orrange says.