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Most Americans don't get anywhere near the recommended amount of 20 to 35 grams per day of fiber. Taking a fiber supplement, like Benefiber, can help improve your fiber intake and lower your risk for constipation. Although the wheat dextrin that makes up Benefiber is generally regarded as safe, if you don't use this product properly, you could experience some unpleasant side effects.

Gastrointestinal Side Effects

Gastrointestinal side effects can sometimes occur with the use of Benefiber or other fiber supplements, including upset stomach, a full feeling, gastrointestinal pain, flatulence, nausea, diarrhea, gas and bloating. These symptoms tend to occur within a few hours of taking Benefiber. Unlike psyllium-based fiber supplements, Benefiber doesn't expand in water, so it doesn't pose a risk of choking.

Allergy and Intolerance Issues

Although Benefiber contains under 20 parts per million of gluten, allowing it to be labeled gluten-free, these small amounts can be a concern for some people. If you have celiac disease, you should avoid taking Benefiber. Some versions of Benefiber contain lactose and should be avoided by those who have a milk allergy or an intolerance to lactose. Likewise, if you feel that aspartame bothers you, read the labels of the different Benefiber varieties, as some contain this artificial sweetener.

Potential Medication Interactions

Fiber supplements can interact with some medications, interfering with their effectiveness. If you take anti-depressants, diabetes medications, cholesterol-lowering medications, the seizure medication carbamazepine, lithium or digoxin, speak with your doctor before taking fiber supplements. In some cases, taking Benefiber two to four hours before or after your medication can limit the risk for interaction.

Minimizing Side Effects

Taking a few simple steps can help you minimize the gastrointestinal side effects that sometimes occur when taking fiber supplements. First, be sure to drink a full glass of water or other noncarbonated beverage each time you take your supplement, and get plenty of water throughout the day. Your body needs more water as you consume more fiber. Second, increase your fiber intake gradually so your body has time to adjust. Start with the minimum dose once a day, and gradually increase your intake, making sure not to exceed the maximum recommended intake for your Benefiber supplement.