dehydration causes constipation

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The Situation: Your fiber-to-water ratio is off.

Why it's causing a backup: Taking in your recommended 25 grams of fiber per day (for women 50 and under—51 and up should aim for 21 grams) without drinking enough water is a recipe for constipation. "Fiber absorbs water," explains Elana Maser, MD, an assistant professor of medicine, gastroenterology, and the director of the Women's Gastrointestinal Health Center at Mount Sinai Hospital, in New York. "So if you're dehydrated, that fiber will turn to cement in your bowels. It's like leaving a bowl of cereal with some milk in the sink without rinsing it. You come back a few hours later and the cereal is stuck to the sides, and it's really hard to get off."

How to fix it: Keep your fiber intake where it is, but drink enough water to keep your pee a light yellow color.
why you're constipated

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The Situation: You've been using laxatives.

Why it's causing a backup: You've been using the wrong ones. Over-the-counter laxatives share the same goal of getting your bowels moving, but they don't do all it in the same way. Osmotic laxatives (like MiraLAX or milk of magnesia) work by drawing water into your bowels from nearby tissue, softening stool so it moves more easily through your digestive system. Stimulant laxatives (look for ingredients like bisacodyl and sennosides), on the other hand, trigger muscle contractions in your intestinal wall that move the contents of your bowels along. Using stimulant laxatives occasionally (think once per month) is fine; if you're taking them daily or every other day, you may find yourself constipated again once you stop. "Your body can become dependent on them," explains Neha Shah, MPH, RD, a clinical dietitian with Stanford Health Care, in California, so you may not be able to have a bowel movement without them.

How to fix it: Switching to osmotic laxatives, which don't lead to dependency, can help. If you still find it difficult to go, see a gastroenterologist, as there are stronger but non-habit-forming prescription laxatives you can try.
travel and constipation

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The Situation: Travel has thrown your normal schedule out the window.

Why it's causing a backup: "The bowels like regularity," Maser says. "So when you change time zones, adjust your mealtimes and skip your normal workouts, you can get backed up." A small study in Digestive Diseases and Sciences found that 9 percent of subjects who were traveling abroad dealt with constipation during their trip. Air travel is a common trigger because plane cabins are very dry. And traveling for work may be especially problematic, Maser notes, because stress can also slow down bowel movement.

How to fix it: Drink enough water in-flight to keep your urine a very pale yellow. Working out can also help, Shah says, as physical activity can improve bowel motility. Vigorous exercise was associated with more-frequent bowel movements in women, according to a study in Public Health Nutrition.
medicine and constipation

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The Situation: You're about to get your period—or you're done with your period for good.

Why it's causing a backup: Progesterone levels are highest during the days leading up to menstruation, known as the luteal phase of your cycle, and the higher the progesterone, the longer it takes for food to travel through your digestive system, Maser says. (It relaxes the smooth muscles in your bowels that normally contract to move food along.) And don't count on not having a period anymore to ease the problem. "Any hormonal shift can lead to changes in bowel motility," Maser adds. In the case of menopause, that means the dryness that's happening elsewhere in your body happens in your digestive system too, leading to—you guessed it—a slowdown. In a study of more than 73,000 postmenopausal women in The American Journal of Medicine, 34.7 percent reported having constipation.

How to fix it: Help counteract the hormonal havoc by drinking plenty of water and getting your recommended fiber intake. If you find that's not enough to prevent backup, talk to your doctor about using osmotic laxatives to ease the constipation.
thyroid and constipation

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The Situation: Your thyroid is slacking off.

Why it's causing a backup: When your thyroid isn't churning out hormones the way it should, a condition called hypothyroidism, a lot of bodily functions can slow down, digestion included. It's most common in women 60 years and older, and you may also notice symptoms like really dry skin, fatigue that won't go away, intolerance to cold temperatures and unexplained weight gain, among others.

How to fix it: If your doctor suspects that hypothyroidism is causing your constipation, they'll order a thyroid-function test and proceed from there. If testing shows that you have it, medications can help manage the problem.
medication and constipation

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The Situation: Medications are to blame

Why it's causing a backup: Certain meds are known to stop people up. Three of the biggest culprits: tricyclic antidepressants, beta-blockers for blood pressure that have a diuretic effect, and any kind of narcotic or opioid (research in Pain found that 41 percent of people taking opioids for up to 8 weeks experienced constipation).

How to fix it: Ask your doctor about alternative medications that treat your underlying condition but don't cause constipation.