Why do some people bruise easily and when do you need to worry about it? An expert explains.

By Kylie Andrews

We’ve all sported the odd black and blue mark from a knock, but for some of us, the slightest bump seems to result in a multi-coloured extravaganza, which might last as long as several weeks.

Other people might find they bruise a lot, even if the bruises themselves are not spectacular, but they cannot recall the impacts that would explain the marks.

So why do some people bruise more easily than others? And can it mean something sinister?

We bruise when something happens to break or burst the blood vessels that carry blood around our bodies.

Red blood cells leak out into the surrounding tissue, but they cannot survive outside the blood vessels so they pool in the flesh and start to break down.

This can result in a kaleidoscope of changing colours as the bruise progresses from black to brown to green to yellow.

It turns out there can be a number of explanations for bruising more easily. Here are some of the most common ones:

You’re a woman

Dr Andrew Miller, dermatologist and senior lecturer at ANU and a spokesman for the College of Dermatologists, said women tend to bruise more easily than men.

Scientists do not know exactly why but it is probably to do with collagen (supporting tissue in the skin) and other factors such as skin thickness and subtle variations in the way blood vessels are supported.

How to treat a bruise:

  • A decent deep bruise can take two to three weeks to go

  • While there are creams around that are supposed to reduce bruising, Dr Andrew Miller said “they probably don’t make a great deal of difference”

  • He suggests a cold pack and pressure to reduce the bleeding

We all have a fibrous matrix that holds our skin together and supports the blood vessels and the fine blood vessels.

Well-supported blood vessels are more tightly held in place and are therefore less likely to break and result in bruising when the skin is pushed or pulled.

While there are many factors that affect the firmness of the supportive matrix, it seems that men tend to have an overall advantage.

“The fibrous layer of the skin is thicker in men, as a rule, than it is in women. So they do have thicker skin,” Dr Miller said.

Getting older

As you get older, the firmness of the fibrous layer of your skin and the fat beneath it decreases.

Like many things as we age, it all starts to get a bit saggy and floppy.

This makes older people more vulnerable to bruising because the internal structure of their skin just is not as capable of holding the blood vessels firmly in place.

“When you bump against things, the skin moves more,” Dr Miller said.

“The shearing is greater and that results in more mechanical stress and more bruising.”


You’ve spent a lot of time in the sun

Unfortunately for sun-lovers (or those of us too old to have been protected by sunscreen), sun exposure really affects the firmness of the skin.

“The analogy I use to my patients is that the sun rots their skin, just like a piece of canvas,” Dr Miller said.

Bruising linked to sun damage is especially common on the forearms in men and women, and the lower legs in women (due to wearing dresses).

Dr Miller said it is consistently the sun-exposed areas that are affected by easy bruising in older people.

“These same people, if they were to do the same relatively minor trauma on their trunk wouldn’t get a mark,” he said.

This bruising is often due to capillary bleeding, which results in the purple-black lesions that can cover the arms and legs of older people.

These bruises form easily and rapidly but take a long time to go, leading to an almost permanent accumulation of bruises.

You’re on certain medications

There are some medications that can have an effect on bruising.

Corticosteroids can cause an increase in easy bruising because they thin out the collagen in the skin.

Antiplatelet drugs (such as aspirin) and anticoagulant drugs (such as heparin or warfarin) can cause excessive bruising, which is when a really big bruise develops from a minor trauma.

“Antiplatelet drugs will interfere with clotting. That won’t necessarily make you bruise easily but you’ll bruise excessively,” Dr Miller said.

“So there has to be some sort of trauma there instead of ‘oh my goodness, I can’t remember anything to give myself that’.”

There are also some health conditions that result in easy or excessive bruising — these include leukaemia, haemophilia, Von Willebrand disease, Ehlers-Danlos Syndrome and a few others.

When do you need to worry about your bruising?

The main thing to look out for is when you sustain a big bruise for a relatively minor reason.

“People who get big bruises with relatively little trauma, then that is an indication that they should probably speak to their doctor about it,” Dr Miller said.

If worried about your bruising then speak to a health professional about it.

This post originally appeared on ABC News.

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