Can Prednisone Cause Gas and Bloating?

Prednisone commonly causes gastrointestinal symptoms, and gas and bloating are among them. In clinical studies, GI disturbances rank as one of the most frequently reported side effects, and a randomized trial in adults with asthma found that gastrointestinal disturbance was reported significantly more often during prednisolone treatment than during placebo.¹ The reasons go beyond simple stomach irritation: prednisone reshapes gut motility, disrupts the microbial communities living in your intestines, and can set the stage for bacterial overgrowth that produces excess gas.

How Common Are Digestive Side Effects on Prednisone

In a study of 55 patients treated with prednisone for oral inflammatory conditions, roughly 55 percent experienced some adverse side effect, and gastrointestinal disturbances topped the list alongside mood changes, increased urination, and insomnia.² That study also found that the duration of treatment mattered more than the daily dose when it came to side effects. In other words, the longer you stay on prednisone, the more likely you are to develop gut symptoms, even if your dose is relatively modest.

A separate randomized controlled trial in adults with asthma confirmed the pattern from a different angle. Participants taking a short course of prednisolone reported gastrointestinal disturbance and sleep disruption significantly more often than those on placebo, even though appetite scores and caloric intake did not differ between the two groups.¹ That last point is worth lingering on: the GI symptoms showed up even when eating habits stayed the same, suggesting something more than just overeating or dietary change is at work.

Among patients with inflammatory bowel disease, who are frequently prescribed steroids, the picture gets more complicated. A survey-based study of IBD patients found that the total number of medications, use of steroids, and use of neuropsychiatric drugs all correlated with higher side-effect scores.³ The challenge in that population is disentangling the drug’s effects from the disease itself, since IBD already causes bloating and gas. But steroid use still independently tracked with worse symptom reports.

How Prednisone Changes Gut Movement

One of the more underappreciated ways prednisone causes bloating involves its effects on the muscular contractions that push food through your digestive tract. In a rat study, prednisone increased the frequency of stomach contractions and sped up gastric emptying at lower doses, but it simultaneously slowed transit through the small intestine.⁴ That combination means food gets dumped into the intestines faster than usual, then sits there longer. When partially digested food lingers in the small bowel, bacteria have more time to ferment it, producing hydrogen and methane gas in the process.

The same study found that prednisone reduced the number of mucosal mast cells in the gut wall, and there was a strong positive correlation between mast cell numbers and intestinal transit speed. Mast cells play a role in regulating how the gut moves, so by suppressing them, prednisone may be indirectly slowing the intestinal conveyor belt. This is an animal model, so the exact numbers do not translate directly to humans, but the mechanism is consistent with the bloating many people describe: food moves through the stomach quickly (sometimes causing nausea or discomfort), then stalls in the intestines.

A canine study using the closely related steroid prednisolone showed a similar pattern in a different species. Dogs treated with prednisolone had significantly delayed gastric emptying compared to controls, with the half-emptying time rising from about 137 minutes to 184 minutes.⁵ That study tested a prokinetic drug (mosapride) alongside prednisolone and found it restored emptying time to near normal, which hints at a practical avenue: motility-promoting medications may help counteract steroid-induced sluggishness.

Microbiome Disruption and Gas Production

Your gut harbors trillions of bacteria that help break down food, and prednisone changes their composition in ways that favor gas production. A study in rats given prednisone for six weeks found significant shifts in gut microbial communities: several bacterial groups that produce short-chain fatty acids declined, while others increased. The reduced production of short-chain fatty acids was linked to the drop in specific beneficial genera.⁶ Short-chain fatty acids are a major energy source for the cells lining your colon and help regulate water absorption and motility. When their production drops, the result can be looser stools, increased fermentation by less helpful bacteria, and more gas.

It is not just bacteria that get reshuffled. A separate rat study found that long-term prednisone treatment caused dysbiosis of the fungal microbiota in the gut and altered the ecological balance between fungi and bacteria.⁷ Fungal overgrowth in the gut, particularly of species like Candida, has long been associated with bloating and excessive gas in clinical practice. When steroids suppress the immune system locally in the gut, opportunistic fungi can expand into niches previously kept in check.

Perhaps most striking, a human study found that even short-term oral glucocorticoid treatment caused measurable gut dysbiosis and metabolic changes in healthy men. Certain bacterial species linked to insulin resistance increased, while others declined, and microbial pathways related to sugar and fat metabolism were altered.⁸ This is notable because these were healthy volunteers with no underlying disease, so the shifts were caused by the steroid itself, not by the condition being treated. Changes in microbial fermentation patterns help explain why bloating and flatulence can show up within days of starting prednisone, not just after months of use.

Small Intestinal Bacterial Overgrowth

When the wrong bacteria colonize the upper part of the small intestine in excessive numbers, the result is a condition known as small intestinal bacterial overgrowth, or SIBO. The hallmark symptoms are bloating, excessive gas, and sometimes diarrhea. A large retrospective study found that steroid use was associated with a higher rate of SIBO compared to non-use, with roughly one in five steroid users affected versus about one in seven non-users. The risk climbed further when steroids were combined with other immunosuppressive drugs.⁹

SIBO develops when the body’s natural defenses against bacterial overgrowth break down. Normally, stomach acid, bile, the immune system, and the sweeping contractions of the small intestine keep bacterial counts low in the upper gut. Prednisone can compromise several of these defenses at once: it suppresses immune surveillance in the gut lining, and as described earlier, it slows intestinal transit, giving bacteria more time to proliferate. If you’re also taking a proton pump inhibitor (a common acid-suppressing medication), the risk compounds. SIBO has been detected in a quarter to two-fifths of patients with irritable bowel syndrome-type symptoms, with gaseous bloating and excessive flatulence being the most characteristic complaints.¹⁰

The practical takeaway is that if you’re on prednisone and experiencing persistent, worsening bloating along with foul-smelling gas or watery diarrhea, SIBO is worth discussing with your doctor. Breath testing can detect it, and treatment typically involves a course of targeted antibiotics.

An Interesting Wrinkle About Irritable Bowel Syndrome

Given everything above, you might expect that steroid users would be more likely to develop irritable bowel syndrome. The evidence actually points the opposite way. A population-level study found that current users of oral steroids had a lower risk of being diagnosed with IBS, and those taking doses above 10 mg of prednisolone daily had about 60 percent of the risk compared to non-users.¹¹ This likely reflects prednisone’s powerful anti-inflammatory properties. IBS involves low-grade inflammation and visceral hypersensitivity in the gut wall, and prednisone directly dampens both of those.

This creates a paradox that confuses many patients. Prednisone can cause bloating through the motility, microbiome, and SIBO mechanisms described above, while simultaneously suppressing the kind of gut inflammation that causes IBS-type bloating. For someone whose bloating is driven mainly by inflammation, prednisone might actually improve things. For someone whose gut was functioning well before they started the drug, the motility and microbiome disruptions can create new bloating where none existed. The net effect depends on what was going on in your gut before you started the steroid.

What Happens When You Stop

Bloating does not always resolve the moment you stop taking prednisone. In fact, withdrawal can temporarily make gut symptoms worse. A surgical case series documented a striking phenomenon: acute ileus from steroid withdrawal. In 43 patients who had undergone surgery for ulcerative colitis, steroid withdrawal triggered episodes of bowel paralysis that mimicked intestinal obstruction, totaling 76 separate episodes.¹² The gut essentially stopped moving. Symptoms resolved quickly once intravenous steroids were administered, confirming that the withdrawal itself was the cause.

That is an extreme scenario involving surgical patients, but the principle scales down. Your body adjusts to prednisone’s effects on gut motility and immune function. When the drug is removed, especially abruptly, there is a transition period where the gut’s normal regulation has not yet reasserted itself. During tapering, some people notice increased gas and abdominal distension that gradually improves over days to weeks. This is one reason doctors taper prednisone slowly rather than stopping it cold. The adrenal glands need time to resume their own cortisol production, and the gut’s motility patterns need time to normalize.

Locally Acting Steroids Cause Less GI Trouble

Not all corticosteroids affect the gut equally. Budesonide, a steroid designed to act locally in the intestinal wall rather than circulating throughout the body, causes substantially fewer systemic side effects than prednisone. A head-to-head trial in Crohn’s disease found that steroid-associated side effects were significantly less common in the budesonide group, affecting 29 patients compared to 48 on prednisolone.¹³ A second trial confirmed this, finding that twice as many patients responded to budesonide without any steroid side effects compared to prednisone.¹⁴

Budesonide is not appropriate for every condition that prednisone treats, since its localized action means it does not suppress whole-body inflammation as effectively. But for gut-specific inflammatory conditions like Crohn’s disease and certain forms of colitis, it can provide comparable disease control with a much lower risk of the systemic side effects that drive bloating, including the motility disruptions and widespread microbiome shifts that come with a drug flooding your entire bloodstream.

Probiotics and Practical Management

If you need to stay on prednisone, there is some evidence that probiotics can partially offset the gut disruption. A study of Crohn’s disease patients compared prednisone alone to prednisone combined with probiotics. The group receiving probiotics had a significantly lower rate of infectious complications, including abdominal distension and diarrhea: about 51 percent experienced infections compared to roughly 93 percent in the steroid-only group.¹⁵ Those are patients with serious underlying disease, so the absolute numbers would look different for someone on a short course for, say, an allergic reaction. But the direction of the finding is encouraging: supporting the microbiome during steroid treatment seems to reduce gut symptoms.

Beyond probiotics, a few practical strategies can help manage prednisone-related bloating:

• Take it with food: prednisone on an empty stomach increases the risk of irritation and nausea, which compounds bloating.
• Eat smaller meals: since intestinal transit slows on prednisone, smaller portions give your gut less material to ferment at once.
• Limit gas-producing foods: beans, cruciferous vegetables, carbonated drinks, and sugar alcohols are harder to tolerate when your gut motility is already compromised.
• Stay physically active: moderate exercise promotes gut motility and can partially counteract the slowing effect of the drug.
• Watch for red flags: severe abdominal pain, complete inability to pass gas, or bloody stools are not normal prednisone side effects and warrant urgent medical attention.

The Gut-Brain Axis and Steroid Mood Effects

Prednisone is well known for causing mood changes, from euphoria and irritability to full-blown anxiety and depression. What is less widely appreciated is that these neuropsychiatric effects can loop back and amplify gut symptoms. Steroids influence the gut microbiota, and the gut microbiota in turn communicates with the brain through what researchers call the gut-brain axis. Perturbations in the microbiome have been linked to changes in stress hormones and behavior.¹⁶ Anxiety and stress independently increase gut sensitivity, accelerate colonic transit, and can produce bloating on their own. When prednisone simultaneously disrupts both the microbiome and mood, these effects compound.

This bidirectional relationship helps explain why some people on prednisone describe their gut symptoms as feeling out of proportion to what should happen from a pill. The drug is not just acting on the intestines directly. It is also changing how your nervous system processes signals from the gut, potentially amplifying the sensation of distension even when the actual volume of gas is not that extreme. If you find that your bloating feels worse during stressful moments while on prednisone, this interaction is a likely contributor. Relaxation techniques and adequate sleep will not eliminate the bloating, but they may blunt the amplification effect that makes it feel worse than it physically is.

When Bloating on Prednisone Is Something Else

While gas and bloating are a recognized side effect of prednisone, not every case of abdominal distension during steroid treatment is caused by the drug itself. Prednisone suppresses the immune system, which means infections that would normally be caught early can develop silently. Abdominal infections, including peritonitis and abdominal abscesses, can present as bloating and distension in a patient whose immune responses are blunted. The Crohn’s disease study mentioned earlier reported abdominal abscesses in both treatment arms, highlighting that infection is a real concern during steroid therapy.¹⁵

Prednisone can also cause fluid retention by affecting how your kidneys handle sodium and water. This produces a different kind of abdominal fullness that feels like bloating but is actually edema. The distinction matters because dietary gas management will not help with fluid retention, while reducing salt intake and discussing diuretics with your doctor might. If your bloating is accompanied by swollen ankles, puffy fingers, or rapid weight gain over days, fluid retention is the more likely culprit than intestinal gas. Both can happen at the same time, so the answer is not always one or the other.