Can Aspirin Help With Anxiety? What the Science Says

Aspirin has real anti-inflammatory effects on the brain, and inflammation does appear to play a role in some anxiety disorders, but the leap from those two facts to “aspirin treats anxiety” is much larger than it sounds. No major medical guideline recommends aspirin for anxiety, no large randomized trial has demonstrated a clear benefit for anxious patients, and the human evidence that does exist is mostly observational or comes from small pilot studies with mixed results. The story is more interesting than a flat “no,” though, because the biological plausibility is genuine and a handful of findings keep the question alive in research circles.

Why Researchers Even Looked at Aspirin for Anxiety

The idea that a common painkiller could affect mood or anxiety traces back to a broader shift in psychiatry: the recognition that chronic, low-grade inflammation in the body can influence the brain. Over the past two decades, studies have repeatedly found that people with anxiety disorders tend to have higher blood levels of inflammatory markers like C-reactive protein (CRP) and certain cytokines. Elevated concentrations of these signals have been described in generalized anxiety disorder, panic disorder, PTSD, and various phobias, though the relationship is not uniform across every study or every patient.¹

A large study using data from the UK Biobank found that people in the top fifth of CRP levels had roughly 12-15% higher odds of elevated anxiety symptoms and generalized anxiety disorder compared to those in the bottom fifth.² A separate genetic analysis in a Dutch cohort similarly found that a genetic predisposition toward higher CRP was associated with increased risk of anxiety disorders.³ Those effect sizes are small, but they point in the same direction, which is what prompted researchers to ask whether dampening inflammation with a well-known, widely available drug like aspirin could make a dent in anxiety symptoms.

What Aspirin Does in the Brain

Aspirin blocks both COX-1 and COX-2, two enzymes involved in producing prostaglandins and other inflammatory molecules. Unlike most painkillers, aspirin’s block on COX-1 is irreversible, which is why even a small daily dose has lasting effects on platelet function and inflammation. Beyond simply blocking inflammatory signaling, aspirin stimulates the body’s own anti-inflammatory “braking signals,” including lipoxins, and reduces blood levels of CRP, TNF-α, and IL-6 without suppressing beneficial immune-regulatory molecules like IL-4 and IL-10.⁴

Aspirin’s effects also reach the brain’s resident immune cells, called microglia. In laboratory studies, aspirin shifted microglia away from an activated, inflammatory state and toward a more protective profile. It strongly reduced the production of pro-inflammatory molecules like IL-1β and TNF-α while increasing anti-inflammatory IL-10. It also changed the expression of multiple inflammation-related genes in a direction researchers describe as broadly beneficial.⁵ These findings come from cell cultures, not living brains, but they illustrate that aspirin doesn’t just reduce inflammation at the margins. It appears to recalibrate the brain’s immune environment in ways that could, in theory, influence mood and anxiety.

Aspirin and the Stress Hormone System

Anxiety and the body’s stress response are closely linked through the hypothalamic-pituitary-adrenal (HPA) axis, the hormonal cascade that controls cortisol release. Several small human studies have tested what aspirin does to this system, and the results are genuinely mixed, which is part of why the field hasn’t reached a clear verdict.

In one pilot study of healthy adults, aspirin pre-treatment significantly reduced the cortisol awakening response, the spike in cortisol that normally occurs shortly after waking, and also improved working memory.⁶ A blunted morning cortisol surge is interesting because an exaggerated awakening response has been linked to anxiety and chronic stress. In another small study, aspirin significantly blunted the cortisol response to vasopressin stimulation in healthy men, suggesting it can dampen the HPA axis when it’s artificially provoked.⁷

But a different small study found the opposite pattern: aspirin actually increased the ACTH response to naloxone stimulation by about 46%, with a corresponding (though not statistically significant) 26% increase in cortisol.⁸ The direction of aspirin’s effect on stress hormones appears to depend on how the HPA axis is being stimulated, which means you can’t simply say “aspirin calms the stress system.” It modulates the system in ways that are context-dependent and not fully understood.

What Human Observational Data Show

The most encouraging human data come from observational studies, which are useful for generating hypotheses but can’t prove that aspirin itself is responsible for the association they find. In a large nationwide cohort study of people diagnosed with cancer, those who used aspirin had a lower rate of developing depression, anxiety, and stress-related disorders compared to non-users. The reduction was about 12% overall, and stronger for people who used aspirin continuously and at low doses.⁹ Among patients with cardiovascular disease, the reduction was about 19%, and among breast cancer patients, roughly 26%.

An earlier study of cardiac patients found a similar pattern: aspirin users reported less depression, anxiety, and worry compared to non-users, as assessed both by self-report and by someone who knew them well. The researchers tried to account for the fact that sicker patients might be more likely to take aspirin and also more likely to be anxious, but the association held after adjusting for coronary artery disease status and other clinical variables.¹⁰

These findings are suggestive, but they carry the standard limitations of observational research. People who take aspirin regularly tend to be engaged with their healthcare, may have other health behaviors that protect against anxiety, and are often taking aspirin for cardiovascular reasons, meaning they may receive closer medical monitoring. Confounding is always lurking in studies like these, which is why randomized controlled trials matter so much.

The Randomized Trial That Disappointed

The most rigorous test of aspirin for mental health to date was the YoDA-A trial, which randomized young adults with moderate to severe depression to receive aspirin, rosuvastatin (a statin), or placebo alongside their usual treatment. After 12 weeks, aspirin showed no significant benefit over placebo on depression scores. In fact, aspirin was actually worse than placebo on a quality-of-life measure.¹¹

This trial wasn’t designed to measure anxiety specifically, and the participants were young (aged 15-25), so it doesn’t necessarily close the door on aspirin for older adults or for anxiety in particular. But it is the best-quality human evidence available, and it landed squarely in the negative column. The gap between the observational data (which looks promising) and this randomized trial (which doesn’t) is something the field still hasn’t resolved.

Conflicting Signals from Animal Research

Animal studies on aspirin and anxiety offer a useful window into mechanisms, but they also highlight a puzzle that hasn’t been solved: the same drug can produce anxiety-like or anti-anxiety effects depending on how it’s given.

In one study, rats that received chronic daily doses of aspirin (mimicking medication overuse) showed significantly increased anxiety-like behavior on standard behavioral tests. The aspirin-treated animals spent far less time in the open arms of an elevated maze compared to controls, a classic indicator of heightened anxiety.¹² The researchers linked this to neural hyperactivity in the amygdala, the brain region most closely tied to fear and anxiety processing.

Yet a separate study found that salicylic acid, aspirin’s active metabolite, had clear anti-anxiety effects at moderate doses in rats. The animals spent more time in the open arms of the maze and made more open-arm entries, both signs of reduced anxiety. The effect appeared to involve the GABA system, the same neurotransmitter system targeted by benzodiazepines like Xanax and Valium.¹³

The difference between these two findings likely comes down to dose and duration. A rat study examining multiple dose levels found that low-to-moderate doses of aspirin increased antioxidant capacity and partially reduced inflammation, while high doses actually increased damage and impaired cognition.¹⁴ This suggests a nonlinear relationship where aspirin’s effects on the brain flip from helpful to harmful above a certain threshold, which would not be unusual for a drug with such broad pharmacological activity.

How Aspirin Compares to Other Anti-Inflammatory Drugs

If the inflammation theory of anxiety is correct, you might expect other anti-inflammatory drugs to show similar effects. The evidence here is uneven. The COX-2 inhibitor celecoxib has accumulated the strongest track record among anti-inflammatory agents tested for psychiatric conditions, with multiple studies and meta-analyses showing benefit as an add-on treatment for major depression.¹⁵ Aspirin’s evidence base for psychiatric conditions is thinner than celecoxib’s, though aspirin has shown some signal for protective effects in schizophrenia and bipolar disorder.¹⁶

An interesting wrinkle emerged from the cancer-cohort study mentioned earlier: while aspirin use was associated with lower rates of anxiety and mood disorders, the use of non-aspirin NSAIDs (like ibuprofen and naproxen) was associated with a higher rate.⁹ This divergence suggests that the effect, if real, isn’t simply about reducing inflammation in a generic way. Aspirin may have unique properties, possibly related to its irreversible COX inhibition, its lipoxin-stimulating effects, or its particular influence on brain immune cells, that other painkillers don’t share.

The Serotonin Connection

There’s another layer to this story that rarely gets discussed outside pharmacology circles. Serotonin, the neurotransmitter most closely associated with anxiety and depression treatment, is stored in large quantities in blood platelets, and aspirin’s main cardiovascular effect is on those same platelets. Research has shown that individual differences in serotonin levels actually influence how well aspirin works on platelets. People with higher baseline serotonin levels retained more platelet reactivity after aspirin exposure, meaning aspirin was less effective at its primary job of thinning the blood.¹⁷

Whether this platelet-serotonin interaction translates into meaningful effects on brain serotonin and therefore mood is unknown. It’s plausible that by affecting platelet serotonin handling, aspirin indirectly influences circulating serotonin levels, but that chain of reasoning has more links than the available evidence can support. It does, however, raise the possibility that aspirin could interact with SSRIs and other serotonergic medications in ways that haven’t been fully mapped. If you’re taking an antidepressant and considering adding aspirin, this is yet another reason to involve your doctor.

Real Risks of Self-Medicating with Aspirin

Aspirin’s familiarity and over-the-counter availability can make it seem harmless, but long-term or high-dose use carries significant risks. The most well-documented concern is gastrointestinal bleeding. In a large prospective study of women, those who used two or more standard-dose aspirin tablets per week had about a 43% higher risk of GI bleeding compared to non-regular users. The risk climbed steeply with dose: women taking more than 14 tablets per week had more than double the risk.¹⁸

Several factors compound this risk, including older age, a history of ulcers or GI bleeding, and simultaneous use of other NSAIDs or blood-thinning medications.¹⁹ Someone self-medicating with aspirin for anxiety might not realize they’re accumulating cardiovascular-level antiplatelet effects on top of whatever other medications they’re taking, and the bleeding risk from aspirin doesn’t plateau with time. It remains elevated as long as you’re taking it.

There’s also a less obvious concern raised by the animal research. The rat study showing increased anxiety with chronic aspirin use was designed to model medication-overuse headache, but the anxiety that accompanied it was a separate finding. The researchers traced it to neural hyperactivity in the amygdala, suggesting that chronic analgesic exposure can itself become a source of anxiety-like brain changes.¹² Translating rat findings directly to humans is always risky, but the possibility that daily aspirin could paradoxically worsen anxiety through overuse-related brain changes is worth taking seriously, especially for anyone tempted to try aspirin as an ongoing self-treatment.

Who Might Benefit and Who Probably Won’t

If aspirin does have anti-anxiety properties, the evidence so far suggests they would be most relevant to a specific subset of people rather than anyone who feels anxious. The observational data showing the strongest associations involved people already taking low-dose aspirin for cardiovascular reasons, particularly those with documented heart disease or cancer.⁹ These are populations with elevated systemic inflammation, which means they’re the ones most likely to have an inflammation-driven component to their anxiety in the first place.

For someone with garden-variety situational anxiety, or anxiety driven primarily by psychological factors like rumination or avoidance, the inflammation pathway is probably a minor player at best. The research linking inflammation to anxiety disorders describes a real but modest statistical association. Having high CRP raises your odds of anxiety by somewhere around 12-15%, not by 200%. That means inflammation is one contributor among many, and knocking it down with aspirin, even if that worked perfectly, would address only a fraction of most people’s anxiety.

The animal data also suggest that dose matters enormously. The anti-anxiety signal appeared at moderate doses, not high ones, and chronic high-dose exposure pushed things in the wrong direction. If there is a therapeutic window, it’s likely narrow and hasn’t been defined in humans for this purpose.

Where Aspirin Research Fits in the Broader Anti-Inflammatory Psychiatry Movement

Aspirin’s potential role in anxiety is really one piece of a larger scientific effort to determine whether anti-inflammatory treatments can help psychiatric conditions. Meta-analyses have found that anti-cytokine treatments can reduce depressive symptoms in people with chronic inflammatory diseases, though the effect appears to depend on how depressed someone is to begin with.²⁰ The field is slowly moving toward a model where inflammatory biomarkers might help identify which patients would respond to anti-inflammatory add-on treatments, but that kind of precision psychiatry is still years from clinical practice.

For aspirin specifically, the evidence is caught in an awkward middle stage. The biological mechanisms are plausible and increasingly well-characterized. The observational human data are suggestive. But the one well-designed randomized trial that tested aspirin for a mood disorder in otherwise healthy young people came up empty, and no comparable trial has been done for anxiety as the primary outcome. Until someone runs a large, properly powered randomized trial of aspirin for anxiety, preferably in a population selected for elevated inflammatory markers, the honest assessment is that aspirin remains an interesting hypothesis rather than a viable treatment. Anyone considering it should weigh the GI bleeding risk against an unproven benefit, which is not a favorable equation for most people.