Bruises can appear after scratching, a common experience. While scratching affects the skin’s surface, the applied force can impact underlying structures, causing a visible mark. This is a normal physiological response to trauma, though its severity varies among individuals. Understanding how these marks form and what influences their appearance is helpful.
How Scratching Leads to Bruises
A bruise, medically known as a contusion, forms when small blood vessels, called capillaries, beneath the skin are damaged. These delicate vessels can rupture from minor impacts. When scratching occurs, especially with intensity or repeated action, it can exert enough pressure to break these capillaries. Blood then leaks from the damaged vessels and pools in surrounding tissues, trapped beneath the skin. This collection causes the characteristic discoloration, which changes from red or purplish to blue, black, green, or yellow as it heals. The body’s natural healing process reabsorbs this leaked blood over time, leading to the bruise’s gradual fading, typically within a couple of weeks.
Why Some People Bruise More Easily
Several factors can influence an individual’s susceptibility to bruising, even from light scratching.
Age
As people age, the skin becomes thinner and loses some protective fatty layer cushioning blood vessels. This makes capillaries more fragile and prone to breaking from minor trauma, leading to senile purpura, common in older adults.
Medications
Certain medications can increase bruising tendency by affecting blood clotting or thinning the skin. Blood thinners like warfarin or aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, can prolong bleeding from damaged capillaries. Corticosteroids, used for various conditions, can also thin the skin, contributing to easier bruising.
Nutritional Deficiencies
Nutritional deficiencies can also play a role. A lack of vitamin C can weaken blood vessel walls, as vitamin C is essential for collagen production. Vitamin K deficiency can impair blood clotting, as it is involved in producing necessary proteins. Iron deficiency anemia and certain B vitamin deficiencies may also contribute.
Underlying Medical Conditions
Medical conditions affecting blood clotting or vessel integrity can also result in easy or unexplained bruising. Examples include certain bleeding disorders (e.g., hemophilia, von Willebrand disease), liver disease, or some blood cancers.
When to Consult a Doctor
While bruising from scratching is often harmless, certain patterns or accompanying symptoms warrant medical evaluation. It is advisable to consult a doctor if bruising appears excessive, occurs frequently without a clear cause, or results from very minimal scratching. Medical attention is important if bruises are accompanied by other unusual symptoms, such as unexplained bleeding from areas like the nose or gums, severe pain, or significant swelling. If bruises do not fade after two weeks or appear in unusual locations like the head, abdomen, or back without a known injury, a doctor should be consulted to rule out any underlying medical conditions.