Laxatives do ease constipation and help you have more regular bowel movements. There's no proof they relieve stomach aches, bloating, and other problems that come with IBS, though. Researchers haven’t done enough of the right kinds of scientific studies to know exactly how well they work.
But that doesn’t mean a laxative won’t help if you have IBS with constipation. If you're thinking about taking one, talk with your doctor first. There are different kinds, and some are safer than others for long-term treatment of constipation. Your doctor can guide you to the one that will help you the most.
If you want to try a laxative, fiber is a good place to start. Ideally, you should get most of it from your diet. You can start by getting a little at a time, and work your way up to 25 grams a day.
But some people may need more help from bulk-forming laxatives. They add soluble fiber to your stool, which makes it easier to pass by absorbing more water in your intestines. Make sure you drink plenty of water when you take one, though. These laxatives include methylcellulose (Citrucel), polycarbophil (FiberCon), and psyllium (Metamucil).
These pull water back into your colon, which softens your stool so it's easier to get it out of your body. They are fairly safe to take for long-lasting constipation. Just make sure you drink plenty of water when you take them to avoid getting dehydrated.
Osmotic laxatives can cause problems for some people, like bloating, diarrhea, and dehydration. In rare cases, some of them may lead to kidney or heart disease.
These laxatives include milk of magnesia, magnesium citrate, sorbitol, polyethylene glycol, and lactulose. You can buy many brands over the counter at the pharmacy.
These usually have a chemical called senna, which triggers muscles around your intestines to squeeze and move stool through your colon. While they do relieve constipation, you shouldn’t take them on a regular basis. When you take them for a long time, your body can get used to them so that they won’t work for you anymore. You can also get dependent on them, during which you need them to stay regular.
Side effects can include diarrhea, upset stomach, vomiting, and stomach cramping.
Talk with your doctor before you take a laxative to see if it will help with your symptoms. Remember, there are other ways to treat IBS with constipation, like medications, fiber supplements, diet changes, stress management, behavioral therapy, and alternative treatments.