Lower back pain can absolutely make you feel sick, which is a surprisingly common experience. The sensation of “feeling sick” often includes symptoms like nausea, general malaise, or profound fatigue. The relationship between severe back pain and systemic discomfort is complex, involving neurological and hormonal responses. Understanding this connection is the first step toward finding relief and identifying when a symptom signals a more serious underlying problem.
How Severe Pain Triggers Systemic Discomfort
Severe or chronic pain triggers a body-wide stress response that results in systemic symptoms like nausea and fatigue. The intensity of the pain signal activates the sympathetic nervous system, often called the “fight-or-flight” response. This activation diverts resources away from non-essential functions, including digestion, which can slow the movement of food through the gut and directly lead to nausea and stomach upset.
Systemic discomfort is also mediated by hormonal pathways in the body. Intense pain causes the release of stress hormones, such as cortisol and adrenaline, alongside neurotransmitters like serotonin. Serotonin plays a significant role in the gastrointestinal tract, and its release can stimulate receptors that trigger feelings of nausea and sometimes vomiting. The constant state of alarm caused by unmanaged pain requires a huge expenditure of energy, which manifests as exhaustion or malaise.
A specific neurological link involves the vagus nerve, which extends from the brainstem to the abdomen and regulates heart rate and digestion. Severe back pain, especially if it involves nerve compression, can indirectly irritate or activate the vagus nerve. Because this nerve influences the gut, this irritation can reflexively result in profound nausea and digestive disruption.
Shared Underlying Conditions That Cause Both Symptoms
When back pain and systemic sickness occur together, it may signal a single underlying medical condition affecting both the spine area and overall health. Kidney issues are a frequent cause, as both a kidney infection (pyelonephritis) and kidney stones often present with flank or lower back pain. A kidney infection is typically accompanied by a high fever, chills, and severe nausea or vomiting.
Pancreatitis, which is inflammation of the pancreas, is another condition capable of mimicking simple back pain. The severe abdominal pain from pancreatitis often radiates to the mid- or lower back. The inflammation severely disrupts digestive function, causing intense nausea and vomiting, especially after eating. Unlike muscular back pain, the discomfort from pancreatitis may feel penetrating and is often not relieved by changing position.
Spinal infections, such as a spinal epidural abscess or discitis, are serious causes where back pain is compounded by systemic illness. These infections are characterized by severe, localized back pain along with constitutional symptoms like fever, chills, and general malaise. The infection can also trigger nausea and vomiting. If left untreated, the abscess can compress the spinal cord, leading to neurological deficits like weakness or loss of bladder control.
Sudden, severe lower back pain and systemic illness may indicate a rupturing abdominal aortic aneurysm (AAA). The aorta runs along the spine, and a rupture causes pain described as tearing or ripping. This is accompanied by signs of internal bleeding and shock, such as a fast pulse, low blood pressure, confusion, or severe nausea. This is a medical emergency requiring immediate intervention.
Medication Side Effects and Critical Warning Signs
Before concluding that a severe underlying disease is the cause, consider the side effects of medications commonly used to treat back pain. Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, are known to cause gastrointestinal upset, irritation, and sometimes nausea or stomach bleeding, particularly with prolonged use. Since these medications are often the first line of defense, they can be the direct cause of the sickness.
Opioid pain relievers, which are sometimes prescribed for severe back pain, frequently cause nausea and vomiting, especially when first starting the medication. Opioids act on the central nervous system and the gastrointestinal tract, often leading to reduced gut motility and constipation. Muscle relaxers, another common treatment, can cause side effects like dizziness and general malaise, which the patient may interpret as feeling sick.
Because of the potential for severe underlying causes, certain symptoms combined with lower back pain are considered critical warning signs, or “red flags,” that require immediate medical attention. Any back pain accompanied by a high fever or chills, unexplained weight loss, or pain that is constant and worsens at night should prompt an urgent evaluation. Sudden, severe, or “ripping” pain, or any new weakness, numbness, or loss of control over the bladder or bowels, demands an immediate emergency room visit to rule out serious conditions.