Can Aspirin Cause Back Pain as a Side Effect?

Short answer: Back pain is not a common side effect of aspirin, but it can occur and may signal something else such as kidney irritation or bleeding that warrants attention. ^[1] Back or side (flank) pain is listed among serious adverse effects that need medical evaluation. ^[1]

What We Know About Aspirin and Back Pain

• Back or side pain is reported as a serious adverse effect. Consumer drug references list “lower back or side pain” among symptoms that can happen with aspirin and should prompt medical advice. ^[1] Similar listings include unusual tiredness, decreased urination, dark urine, and swelling, which may suggest kidney strain or bleeding. ^{[2] [3]}
• Aspirin is intended to relieve musculoskeletal pain (including backache). Many labels cite muscular aches and backache among uses, so new or worsening back pain while taking aspirin is unexpected and should be assessed. ^{[4] [5] [6]}
• Bleeding risk is a known issue with aspirin. As a nonsteroidal anti‑inflammatory drug (NSAID), aspirin can increase the risk of stomach and other bleeding, especially in older adults or those on anticoagulants or steroids. Bleeding can sometimes present with back or flank pain if the kidneys or retroperitoneal area are involved. ^{[7] [8] [9]}

Possible Reasons for Back Pain During Aspirin Use

• Kidney irritation or reduced kidney function: Lower back or flank pain, decreased urine, dark urine, swelling, and increased thirst may indicate kidney involvement and need prompt evaluation. ^{[1] [2]}
• Gastrointestinal or internal bleeding: Black stools, vomiting blood, unusual bruising, or persistent weakness with back pain could reflect bleeding complications. ^{[2] [3] [7]}
• Drug interactions or co‑morbid conditions: Combining aspirin with other NSAIDs, anticoagulants, or steroids raises bleeding risk and may complicate pain symptoms. ^{[7] [8] [9]} Aspirin use with certain procedures (e.g., neuraxial/epidural) is generally considered safe for major bleeding but requires individualized risk review. [PM15]
• Coincidental mechanical back pain: You might simply have a back strain unrelated to aspirin; however, new or unusual pain patterns during aspirin therapy deserve a check, especially with any “red flag” signs. ^{[4] [5] [6]}

Red Flags: When to Seek Urgent Care

Seek urgent medical care if back or side pain is accompanied by any of the following:

• Decreased urination, dark urine, swelling of legs/face, or marked fatigue possible kidney involvement. ^{[1] [2]}
• Black, tarry stools; vomiting blood; unusual bleeding or bruising possible internal bleeding. ^{[2] [3] [7]}
• Light‑colored stools, upper right abdominal pain, loss of consciousness, severe nausea/vomiting possible serious systemic effects. ^{[1] [3]}

These combinations of symptoms while on aspirin merit immediate evaluation and stopping the drug until a clinician advises further. ^{[2] [7]}

Practical Ways to Cope Safely

• Stop aspirin and check with a clinician if you develop new or worsening back/side pain. This is especially important if you notice any red‑flag symptoms listed above. ^{[1] [2]}
• Hydrate and avoid additional NSAIDs. Using multiple NSAIDs together increases bleeding and kidney risk; do not add ibuprofen or naproxen on top of aspirin unless your clinician approves. ^{[7] [8] [9]}
• Consider alternative pain options if appropriate. Depending on your history, a clinician may suggest acetaminophen (paracetamol) for pain instead of an NSAID, or non‑drug measures like heat, gentle mobility, or physical therapy. Always individualize based on your medical conditions and medications. ^{[5] [6]}
• Use the lowest effective dose for the shortest time. This general rule for over‑the‑counter pain relief helps reduce adverse effects. ^{[9] [10]}
• Review your medication list for interactions. Anticoagulants, steroids, and multiple NSAIDs increase bleeding risk; alcohol use also raises risk. ^{[7] [8] [9]}
• Monitor stool and urine changes. Early recognition of black stools, reduced urination, or dark urine can help catch complications sooner. ^{[2] [1]}
• If aspirin was recommended for heart protection, do not stop without guidance. For cardioprotective use, talk to your clinician to weigh risks and benefits and consider alternatives if back pain arises. ^[9]

Who Is at Higher Risk

• Adults over 60, prior ulcers or bleeding problems, and those on blood thinners or steroids face higher bleeding risk with aspirin. These groups should be especially cautious with new back or side pain. ^{[7] [8] [9]}
• People with kidney disease or dehydration may be more susceptible to kidney‑related side effects; watch for flank pain and urine changes. ^{[1] [2]}

Bottom Line

• Aspirin can rarely be associated with lower back or side pain, and when it occurs, it may point to kidney or bleeding issues that need medical attention. ^{[1] [2]}
• Because aspirin is also used to treat backache, new or worsening back pain while taking it is atypical and should be discussed with a clinician especially if any red‑flag symptoms are present. ^{[4] [5] [6]}