Common Medications That Can Cause Constipation

Constipation, or having difficulty or the inability to pass stool, is an occasional and unfortunate occurrence that most of us will experience from time to time. According to the Mayo Clinic, it can be caused by a wide array of things, including a low-fiber diet, lack of exercise, and not getting enough fluids. It could also be brought on by certain medical conditions, such as diabetes, irritable bowel syndrome, Parkinson's disease, and even pregnancy. 

Additionally, certain medications can also be at the root of your constipation (via News Medical Life Sciences). Both prescription and non-prescription medications can trigger this condition, so taking multiple medications at once will most likely increase your chances of becoming constipated. Elderly patients in particular are at risk, as shown by a 2018 study published in the International Journal of Environmental Research and Public Health. In that study, 33.9% of elderly patients reported constipation as a side effect of their medication use. 

These are just a few of the medications that you should be wary of if your doctor prescribes them.  

Opioid medications such as hydrocodone, oxycodone, and morphine are effective at blocking pain signals to the brain and, as such, can be an effective treatment for acute pain (via Johns Hopkins). However, given that these medications are so powerful, it's important to take caution and use them wisely. One of the effects of opioid use, for example, is a feeling of extreme pleasure and euphoria. People taking these medications often want to keep experiencing those feelings of pleasure, which, over time, could lead to opioid addiction. Johns Hopkins notes that 75% of opioid addicts in the U.S. started out taking them as part of a prescription. 

However, even for people who don't become addicted, opioid use still carries certain risks. According to a 2023 article published by StatPearls, anywhere from 40% to 60% of opioid users can experience opioid-induced constipation. This is primarily because opioids inhibit the movement of stool through the bowel. Over time, the fluid in your stool is absorbed back into your body, making that stool harder and more difficult to pass. Under these circumstances, you may want to talk to your doctor to try and return your bowel function to normal. But a high-fiber diet and laxatives can be a good place to start. 

If you or anyone you know needs help with addiction issues, help is available. Visit the Substance Abuse and Mental Health Services Administration website or contact SAMHSA's National Helpline at 1-800-662-HELP (4357).

Certain antidepressants, known as tricyclic antidepressants, are used to treat a number of conditions, including depression, panic disorder, and obsessive-compulsive disorder. While they are effective at treating these conditions, tricyclic antidepressants also block the production of the neurotransmitter acetylcholine. According to Mental Health America, acetylcholine is an amino acid that aids in muscle contraction. When its production is disrupted, it can make it hard for stool to move through your system. 

If you experience constipation as a result of taking tricyclic antidepressants, the Mayo Clinic recommends drinking water regularly, getting plenty of exercise, and consuming a high-fiber diet with plenty of fruits, vegetables, and whole grains. Many of these foods, as well as meat, poultry, eggs, and fish, are also high in choline (via the National Institutes of Health). A choline-rich diet can help boost the body's levels of acetylcholine, which can go a long way toward easing constipation symptoms.  

For patients with high blood pressure, calcium channel blockers can be an effective treatment (via the Mayo Clinic). These drugs prevent calcium from entering the arteries and blood vessels, relaxing them and allowing blood to flow through more freely. They're also effective against other heart-related issues, including coronary artery disease, irregular heartbeat, and angina.  

However, the muscle-relaxing effects caused by channel blockers can have unfortunate side effects (via GoodRx Health). These medications can also affect the muscles of your stomach and bowel, impacting the movement of stool through your system. A 1998 study published in Diseases of the Colon and Rectum confirmed the effect of calcium channel blockers on the colon. The drugs nifedipine and verapamil can both inhibit colonic movement. GoodRx notes that, for calcium channel blocker patients who suffer from constipation, an over-the-counter laxative may be a good solution. But those should only be used in short-term cases. If you are experiencing prolonged constipation while taking calcium channel blockers, you should talk with your doctor. 

Non-steroidal anti-inflammatory drugs, commonly known as NSAIDs, such as ibuprofen and aspirin, are used to treat a wide array of inflammation disorders (via Cleveland Clinic). They can also be effective in combating everything from arthritis pain to menstrual cramps. Because of their versatility, NSAIDs are often patients' first resource when it comes to pain management. According to a 2018 study published in Aging and Disease, NSAIDs account for between five and ten percent of medications prescribed every year. Among elderly patients, NSAID use can be as high as 96%. 

One way that NSAIDs work is by reducing prostaglandin production in the body, according to the Arthritis Foundation. These compounds are produced by an enzyme known as cyclooxygenase, which, in addition to playing a role in inflammation. When the production of cyclooxygenase is suppressed by NSAIDs, it can impact stomach and bowel function. A 2012 study published in Clinical Endoscopy showed that NSAID use and the suppression of cyclooxygenase could play a role in a number of gastrointestinal disorders, including constipation. 

If you suffer from allergies, antihistamines are undoubtedly something you are intimately familiar with. True to their name, antihistamines are effective at blocking histamines, chemicals formed by allergens such as dust, pollen, ragweed, and pet dander (via WedMD). These histamines are what cause the itchy skin, runny nose, and puffy eyes that so many allergy sufferers have to deal with. 

Unfortunately for people who are struggling with allergies, antihistamines can bind you up in addition to alleviating your symptoms. According to Kaiser Permanente, antihistamines such as Benadryl and Chlor-Trimeton have anticholinergic properties, meaning that they block the effect of acetylcholine in the body. When this neurotransmitter is blocked, it becomes harder for signals to be transmitted through the nervous system. This can cause a wide range of effects ranging from drowsiness to, yes, constipation. This is because acetylcholine stimulates the vagus nerve, which aids in the peristalsis process during digestion (via Rupa Health). When that process is disrupted due to low acetylcholine levels, constipation is the end result. 

Conditions such as heartburn, acid reflux, and indigestion are all the result of too much acid in the stomach (via Cleveland Clinic). This excess acid is the result of an enzyme known as pepsin, whose primary function is to break down food for digestion. According to a 2023 article (via StatPearls), there can be a number of active ingredients that can contribute to the acid-fighting properties of these medications, including calcium and aluminum. 

Antacids that have aluminum present in them can be a trigger for constipation, according to the Tampa Bay Reflux Center. This is because aluminum can have an effect on the rate of contraction in the stomach and intestines. In the case of antacids with calcium, Healing Duo Integrative Medical Practice notes that the calcium can bind to minerals in your digestive tract, throwing off the levels of these minerals in the body and making you feel constipated. In addition, the very reason you're taking antacids could also be the culprit. When the production of stomach acid is slowed, the breakdown of food and the overall digestive process can also be slowed, making it harder for you to comfortably have a bowel movement. 

While most people can get their daily dose of iron from a wide range of staples, such as meat, dried fruit, and beans, there are still cases where people can fall short of their daily iron requirements (via WebMD). In fact, iron deficiency is the most common nutritional deficiency in the United States, with almost 10% of women suffering from low iron. In these cases, it may be necessary to add iron supplements to the diet in order to meet one's daily nutritional requirements. 

However, it's been shown that iron supplements can play a role in constipation. A 2020 review published in Microbiology Research showed that 60% of people taking iron supplements experience gastrointestinal side effects, including constipation, abdominal pain, and bloating. It's not entirely clear why these supplements cause the particular condition, but another 2020 review published in Cureus posits that excess iron in the stomach leads to more water transportation into the intestines. This water is then pulled from the lower gastrointestinal system to keep the rest of the system in balance. With less water in the GI system, stools can harden and become more difficult to pass.  

Diuretics, more commonly called water pills, are among the top 15 most prescribed drugs in America and are most frequently used to treat high blood pressure (via Cleveland Clinic). These pills work with your kidneys, helping them to take excess salt out of the body, where it is then excreted out via your urine. They're also helpful for treating conditions caused by too much fluid buildup in the body, including heart failure and ascites. 

The benefits of diuretics when it comes to blood pressure are evident, as noted by Rush Memorial Hospital. The less fluid in your body, the lower your blood pressure will be. The downside is, as your body's fluid levels are lowered, it can impact the kidney's ability to keep your electrolyte levels in balance. When the levels of electrolytes (such as sodium and potassium) are thrown off, it can lead to problems. A 2021 study published in Frontiers in Pharmacology showed that electrolyte imbalance disrupts the movement of fluids in the body, which can result in you either experiencing diarrhea or, on the opposite side of the spectrum, constipation. 

People who suffer from diarrhea and inflammatory bowel disease can take loperamide (sold under the brand name Imodium). This is also a drug that can be used at prescription strength to help people who have recently had ileostomies manage their symptoms. The drug works by slowing down movement in the bowel and decreasing the amount of fluid passing through the digestive system (via MedlinePlus).  

Due to the way the drug works, one of the more common side effects of loperamide is constipation, per Medical News Today. Loperamide tapers off your digestion process, allowing food to move more slowly through your system, which can help to temper the symptoms of diarrhea. However, it can also slow things down too much, leaving you constipated in the long run. 

In more serious cases, loperamide can cause a condition known as paralytic ileus. According to the Cleveland Clinic, paralytic ileus occurs when the muscles that aid in digestion become paralyzed without anything physically blocking the intestine. If you feel you may have this condition as a result of loperamide, consult with your doctor immediately.