Several common medication categories can cause easy bruising, including over-the-counter pain relievers, blood thinners, antidepressants, and corticosteroids. In many cases, the bruising is a known side effect rather than a sign of something dangerous, but sudden or unexplained bruising after starting a new medication deserves attention.
Understanding which drugs affect bruising, and how they do it, can help you have a more informed conversation with your doctor about whether a change is needed.
Over-the-Counter Pain Relievers (NSAIDs)
Aspirin, ibuprofen, and naproxen all belong to a class of drugs called NSAIDs, and they’re some of the most common culprits behind unexplained bruises. These drugs work by blocking an enzyme called COX-1, which plays a key role in helping platelets clump together to form clots. When that process is suppressed, even minor bumps can bleed under the skin longer than usual, producing a visible bruise.
There’s an important difference between aspirin and other NSAIDs. Aspirin permanently disables the clotting ability of each platelet it touches, and since platelets live for 8 to 9 days and can’t repair themselves, the effect lasts until your body makes fresh ones. Ibuprofen and naproxen, by contrast, bind reversibly, so their effect on clotting wears off as the drug leaves your system. This is why people on daily low-dose aspirin tend to bruise more persistently than those who take ibuprofen occasionally.
Blood Thinners and Antiplatelet Drugs
Prescription anticoagulants like warfarin and direct oral anticoagulants (sometimes called DOACs) are designed to reduce clotting, so bruising is essentially a built-in trade-off. In studies of patients undergoing minor surgical procedures, bruising and pocket hematomas occurred in roughly 2% to 6.5% of patients on warfarin therapy, compared to about 1.2% when no anticoagulant was present. Patients on antiplatelet drugs like clopidogrel showed similar rates, with about 8% to 10% developing significant bruising after procedures.
If you’re on a blood thinner for a heart condition, stroke prevention, or a clotting disorder, some degree of easy bruising is expected. The key concern isn’t the occasional bruise on your arm or shin. It’s bruising that appears on your torso, face, or back without any known injury, or bruising accompanied by other bleeding such as blood in your urine, nosebleeds that won’t stop, or unusually heavy periods.
Antidepressants (SSRIs and SNRIs)
This one surprises many people. Common antidepressants like sertraline, fluoxetine, and venlafaxine can increase bruising through an indirect mechanism involving serotonin. Platelets don’t just use clotting proteins to do their job. They also rely on serotonin, which they absorb from the bloodstream and release during clotting to help blood vessels constrict and wounds seal. SSRIs and SNRIs block that serotonin uptake in platelets the same way they block it in the brain, leaving platelets with less serotonin to work with. The result is weaker platelet clumping and a higher chance of bruising or minor bleeding.
The risk increases when SSRIs are combined with NSAIDs or blood thinners. If you take an antidepressant alongside daily aspirin or ibuprofen and notice new bruising, that combination is a likely explanation.
Corticosteroids (Oral and Topical)
Long-term use of corticosteroids, whether taken as pills like prednisone or applied to the skin as creams, can cause bruising by physically weakening the skin itself. Steroids suppress the cells that produce collagen, elastin, and other structural proteins in the skin’s deeper layers. Over time, this leads to thinner, more fragile skin where blood vessels sit closer to the surface and rupture more easily.
With topical steroids, skin thinning can begin surprisingly fast, within 3 to 14 days of starting use. The changes affect every layer of the skin: collagen production drops, elastic fibers fragment and thin out, and the structural support around small blood vessels deteriorates. Clinically, this shows up as visible veins, easy tearing, and purple bruises that seem to appear from minimal contact. For most conditions, doctors recommend limiting topical steroids to the lowest effective strength and using them for no more than 2 to 4 weeks continuously.
Oral corticosteroids taken for months or years produce similar changes throughout the body, not just where the drug is applied. People on long-term prednisone for autoimmune conditions or chronic lung disease frequently notice bruising on the forearms, hands, and other areas with naturally thinner skin.
Chemotherapy Drugs
Chemotherapy causes bruising through a different pathway. Rather than interfering with how platelets work, many chemo drugs reduce the total number of platelets your bone marrow produces. A normal platelet count falls between 150,000 and 400,000 per microliter of blood. Bruising risk begins to climb noticeably once the count drops below 75,000, at which point the odds of bleeding roughly triple. When counts fall below 50,000, the probability of a bleeding event ranges from 0% to nearly 10%. Below 10,000, spontaneous bleeding, including bruising with no injury at all, becomes common, with rates as high as 40%.
Platelet counts typically hit their lowest point 7 to 14 days after a chemotherapy cycle and recover as the bone marrow rebuilds. During that window, new bruises, tiny red dots on the skin (called petechiae), and bleeding gums are all signals that platelet levels are low.
Herbal Supplements
Several popular supplements have documented effects on platelet function and can contribute to bruising, particularly when combined with other medications on this list. Garlic supplements inhibit platelet clumping through multiple pathways, including blocking the same COX enzyme targeted by aspirin and interfering with chemical signals platelets use to activate each other. Ginkgo biloba contains compounds called ginkgolides that prevent platelets from aggregating by blocking a specific activating molecule on platelet surfaces. Studies in human volunteers have confirmed significant platelet inhibition after ginkgo use.
Because supplements aren’t always discussed during medical visits, they’re an easy-to-miss contributor to unexplained bruising. Someone taking a daily ginkgo supplement alongside low-dose aspirin, for example, may be compounding the antiplatelet effect without realizing it.
Why Age Makes Medication-Related Bruising Worse
Aging skin loses connective tissue, subcutaneous fat, and structural support around small blood vessels. The junction between the skin’s outer and inner layers flattens, and years of sun exposure accelerate the damage. This age-related fragility, sometimes called actinic purpura, produces the dark purple blotches commonly seen on the forearms and hands of older adults.
Medications amplify this process significantly. Aspirin, NSAIDs, and anticoagulants are all closely associated with worsening actinic purpura. An older adult on daily aspirin for heart protection and a topical steroid for eczema is experiencing two separate mechanisms of skin and vascular weakening at once. This layering of risk factors explains why bruising often becomes dramatically worse in people over 65 who take multiple medications.
When Bruising Signals Something Serious
Most medication-related bruising is a nuisance, not an emergency. But certain patterns warrant a call to your doctor. Large bruises appearing on the chest, abdomen, back, or face without a clear cause are more concerning than bruises on the shins or forearms, where minor bumps are common. Bruising that starts suddenly after beginning a new medication is worth reporting, even if the drug isn’t typically associated with bruising. Easy bruising paired with other bleeding, such as prolonged bleeding from small cuts, heavy menstrual periods, or bleeding gums, suggests a more significant clotting problem that may need lab work to evaluate. A family history of easy bruising or bleeding disorders also raises the index of suspicion for an inherited condition rather than a medication effect.