Does amoxicillin cause constipation?

In this article:

• Amoxicillin and constipation
• Other factors causing constipation
• When to call your provider
• Managing constipation
• The bottom line

In this article

• Amoxicillin and constipation
• Other factors causing constipation
• When to call your provider
• Managing constipation
• The bottom line

Amoxicillin is a widely prescribed antibiotic used to treat bacterial infections, including bronchitis, pneumonia, and infections of the ear, nose, and throat. It belongs to the penicillin class of antibiotics and is not effective against viruses, such as those that cause the common cold or flu.

While stomach-related side effects can occur, constipation is not common. Amoxicillin is more likely to cause digestive symptoms such as diarrhea, nausea, or stomach discomfort.

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Can amoxicillin cause constipation?

“Constipation can happen with amoxicillin, but it’s much less common than diarrhea,” explains Reshma Patel, Pharm.D., founder of WiseMedRx. “Diarrhea is by far the more frequently reported digestive side effect because antibiotics disrupt normal gut bacteria.”

“Constipation only affects a small minority of people who take amoxicillin,” says Roberto Valledor, MD, a family medicine provider based in Texas. “However, it’s not unheard of, so you shouldn’t ignore it if you have symptoms.”

In the process of destroying the bacteria causing your infection, antibiotics also “temporarily reduce beneficial bacteria in the gut,” Dr. Patel adds. “Those healthy bacteria play an important role in digestion, stool consistency, and intestinal motility.”

Shifts in your gut microbiome can cause some people to experience looser stool, while others experience slowed gut motility, making bowel movements more difficult. “The response really depends on the individual’s baseline microbiome, diet, and overall health,” Dr. Patel explains. “In my experience, patients who already struggle with occasional constipation are more likely to notice a change.”

Why else might you be constipated while taking amoxicillin?

While gut disruption is a common side effect of antibiotics, antibiotics are rarely the only cause of constipation during a bacterial illness. While antibiotics cause constipation in some cases, it is just as likely that changes to your usual diet and routine are the culprit of your constipation while taking amoxicillin. “It’s important to note that constipation during an illness is often multifactorial (less fluid, less fiber, less activity) and may not be solely the antibiotic,” Dr. Valledor notes

Being sick usually means some temporary changes to your lifestyle and wellness routine, all of which could add up to your body not acting like its usual self. 

Reduced appetite and lower fiber intake

When you are sick, you may eat less as illness affects your appetite. You may also be drawn to certain comfort foods that are low in fiber (crackers, broth, popsicles), which can slow your digestive system. Incorporating fiber-rich foods into your diet while you are taking antibiotics (and always) is a great way to avoid experiencing constipation. 

Dehydration from fever or poor fluid intake

Being dehydrated can cause constipation, as water is necessary for fiber to do its job in the intestines, keeping stools soft and easier to pass. A lack of fluids can cause the colon to absorb the water in the stool, turning it from soft to hard. 

Less physical activity

Keeping up with a regular fitness routine can help the colon contract, making waste move more effectively through the gastrointestinal system. This helps prevent constipation and address overall digestive health. When you are sick, you are less likely to stick to your exercise routine, which could contribute to constipation while taking amoxicillin. 

Disrupted routines

If you’ve ever traveled for a vacation or work trip and noticed that your usual bathroom routine seems a bit off, that’s because of a disruption to your normal routine. A disrupted routine can be a reason for constipation, and being ill can certainly mess with your digestive schedule, as you may not be sleeping the same number of hours, waking at your usual time, or eating your usual diet. Your body is likely used to using the bathroom at certain points during your usual day, and if you are sick, your usual day is probably looking a bit different. 

Stress

Being stressed can slow down the gut, which can easily lead to constipation. The body and mind can be in a state of stress when fighting off a virus or bacterial illness, and stress can cause changes in the digestive system, including constipation and an upset stomach.

When should you be concerned about constipation?

As our experts have noted, when taking amoxicillin, as with most antibiotics, the gut microbiome is altered as the antibiotic targets all bacteria, including “good” bacteria that are beneficial to your gut health. Nausea and diarrhea are both relatively common side effects of amoxicillin because of those changes. While most people who experience digestive issues while taking antibiotics suffer from looser stools rather than constipation, it’s still possible to have a bowel slowdown while taking amoxicillin that results in a short period of mild constipation. This could also have to do with factors discussed earlier related to being ill and the changes occurring in your body and routine. 

That said, it is important not to ignore more severe gut symptoms that could point to a more serious problem, requiring consultation with a healthcare professional or even a visit to the hospital for medical attention. According to both of our experts, these more serious side effects include: 

• Severe or worsening abdominal pain
• Persistent vomiting, as this may point to a possible bowel obstruction
• Blood in the stool or black, tarry stools
• Lack of any bowel movement for more than three to four days 
• Significant abdominal bloating with inability to pass gas
• Fever coupled with stomach pain and constipation 

Managing constipation while on amoxicillin

Knowing that antibiotics like amoxicillin can cause constipation or loose stools, it’s smart to be proactive about managing your gut health while taking the medication. Drs. Patel and Valledor suggest:

• Hydration: Drink plenty of water, unless medically restricted. Dr. Valledor suggests at least eight glasses of water each day.
• Fiber: Dr. Patel says it’s a good idea to gradually increase dietary fiber through fruits, vegetables, whole grains, or a fiber supplement if needed. “Water and fiber should be the foundation of your diet to minimize the chance of constipation,” notes Dr. Valledor.
• Movement: Gentle activity, even short walks, stimulates bowel motility.
• Probiotics and probiotic supplements: “While evidence varies, certain probiotics may help support microbiome balance during antibiotic use,” Dr. Patel says. “Foods that contain probiotics, such as yogurt or fermented foods like kefir, may support the good bacteria in your digestive tract while you’re taking an antibiotic,” Dr. Valledor adds.
• Osmotic laxatives: If needed, short-term use of polyethylene glycol (like Miralax) is generally well tolerated, according to Dr. Patel.

“I always recommend addressing lifestyle factors first and escalating thoughtfully if symptoms persist,” says Dr. Patel. Check with your pharmacist before starting any new supplements or over-the-counter remedies to make sure you avoid any drug interactions, and time them appropriately with your antibiotic dose.

Above all, don’t stop taking your antibiotic without consulting your provider. “If you stop taking antibiotics too soon, you risk the infection returning or your body developing antibiotic resistance.” Dr. Valledor shares.

The bottom line

Amoxicillin is not as likely to cause constipation as it is to cause loose stools and nausea, but since constipation is possible, it’s important to be proactive about your gut health while undergoing antibiotic treatment. If you have concerns about past antibiotic use and how your digestive system reacted, get medical advice on the best course of action before starting an antibiotic like amoxicillin. 

“Constipation alone is typically not a reason to stop amoxicillin,” Dr. Patel notes. Instead, she recommends managing constipation safely while completing the course of antibiotics. “However, if constipation is severe or accompanied by concerning symptoms, patients should contact their healthcare provider for guidance rather than discontinuing the medication on their own,” she cautions.