Diarrhea and Alzheimer’s Disease

WebMD Medical Reference in Collaboration with the Cecil G. Sheps Center at the University of North Carolina at Chapel HillLogo for UNC Chapel Hill, Cecil G. Sheps Center
Medically Reviewed by Minesh Khatri, MD on August 30, 2022
4 min read

Diarrhea is when a person has three or more unformed or watery stools in a 24-hour period. It often affects older people and those with Alzheimer’s disease.

Call 911 or take your loved one to the emergency room or doctor’s office right away if they have any of these:

  • Fever above 101 F
  • Blood in the stool. Check their anus and buttocks for any cuts or irritation first. But get to a doctor if there’s a lot of blood, or the stools are black and tarry or cranberry-colored.
  • Belly pain or swelling
  • Vomiting blood or black, coffee-like granules, or they vomit for more than 24 hours
  • Signs of dehydration, like rarely peeing, dark yellow urine, dry tongue, sunken eyes, confusion, weakness, a fast heart rate, or trouble talking
  • Your loved one is more easily distracted and forgetful than usual, has less energy, sees things that aren’t there, has sudden changes in personality and behavior, is strangely emotional, or rambles when they talk.

Call their doctor if your loved one has:

  • More than six unformed or watery stools in a 24-hour period
  • Greasy, pale, foul-smelling stools
  • Constipation followed by diarrhea
  • Diarrhea that lasts longer than a week
  • Slow weight loss even though they’re eating
  • Nausea or belly pain for more than 2 days
  • A low-grade fever (99-101 F) that lasts for more than 2 days

Some of the most common causes of diarrhea in older people include:

  • Bacteria or viruses. More serious infections may cause vomiting as well.
  • Medication: Some medications, especially antibiotics, can upset the gastrointestinal (GI) tract and cause diarrhea. Others make it more likely to get an infection in your GI tract.
  • Irritable bowel syndrome (IBS): If someone has diarrhea with cramps for no clear reason, they may have IBS. Certain foods, lack of exercise, or a high amount of stress can make it worse.
  • Recent abdominal surgery: Surgery in the belly area, especially on the intestines or the gallbladder, can cause it.
  • Inflammatory bowel disease (IBD): This happens when the body attacks the intestines and makes them raw and irritated. Ulcerative colitis and Crohn’s disease are two types of this disease.
  • Malabsorption syndromes: These happen when your body doesn't take in enough nutrients through your intestines. Lactose intolerance and celiac disease are examples.

If your loved one has diarrhea, give them plenty of fluids to drink. If they can keep liquids down, give them sports drinks, juice, or soda without caffeine, even if they don’t feel thirsty. Water is OK too, but it doesn’t put back the sodium and potassium that diarrhea pulls from their bodies. Avoid liquids with caffeine or alcohol, like coffee, some sodas, wine, or beer.

Someone who’s vomiting and can’t keep liquids down can get dehydrated. You might give them small amounts, like a tablespoon or two every 15 minutes. But if they can't keep any liquids in their stomach for longer than 48 hours, call a doctor. Your loved one may need IV fluids.

Offer them low-fiber, easy-to-digest foods like saltine crackers, toast, eggs, chicken, yogurt, or rice.

Diarrhea is how the body gets rid of a bacterial or viral infection. If you give medicine to stop it, the infection will stay in the body longer and cause more pain. If you need to give medicine, you can buy bismuth salicylate and loperamide without a prescription.

Don’t use these drugs if your loved one has recently been constipated, has a high fever or swollen belly, or still has diarrhea after 2 days. Don’t give them to anyone with blood in the stool, cranberry-colored stool, or black, tarry stool. If your loved one gets constipated, stop using loperamide. Don’t give bismuth if they take aspirin or have an allergy to aspirin.

You can do several things to keep your loved one from getting diarrhea. Wash and cook their food thoroughly. Cook meat until it is well done (no pink or red at the center). Use clean kitchen utensils, and wash the surfaces where you prep and cook.

Be sure your loved one washes their hands with soap and water often, especially after using the bathroom and before eating.

Stay away from spicy, heavily seasoned, or high-fat foods. Make sure they get plenty of fluids and fiber.

Some supplements or over-the-counter medicine can cause diarrhea. Talk to your doctor about anything you plan to use. You may want to try probiotics. These supplements have normal intestinal bacteria that might help to stop diarrhea. You can find them at the drugstore.

Since bacteria and viruses cause most cases of diarrhea, make sure you don’t get sick either. Wash your hands with soap and water often, especially before cooking and meals, and after you’re around anyone who’s sick. Wear rubber gloves when you help your loved one around the toilet, clean them, or put any creams around their anus. Clean the toilet and sink with disinfectant cleaners, like bleach wipes. Don’t let these cleaners touch your eyes and skin, as they can cause irritation.