Metamucil is an over-the-counter laxative with the active ingredient of psyllium, a soluble fiber derived from a plant called Plantago ovata. Psyllium can help relieve constipation, diarrhea and a variety of other disorders and may also help lower cholesterol, according to the University of Maryland Medical Center. But Metamucil does cause side effects and other risks, so consult your doctor before taking Metamucil.
Metamucil works as a laxative because when mixed with fluid, the psyllium thickens and swells into a semi-solid mass that helps push stool through the digestive tract. But this swelling can also pose a risk of choking or intestinal blockage if the product is not taken with adequate liquids, according to UMMC. To prevent this problem, always take Metamucil with a full 8 oz. glass of water and drink at least six to eight glasses of water throughout the day. Do not take Metamucil if you have trouble swallowing or have any kind of narrowing or obstruction of the esophagus or digestive tract as your risk of choking or intestinal blockage is higher than normal.
The psyllium in Metamucil can cause a serious allergic reaction, according to the American Cancer Society. This can cause breathing problems, rash, hives and even lead to anaphylaxic shock, which can be deadly. Touching psyllium or breathing in psyllium dust can cause these reactions but they are most common in those who have frequent exposure to its dust. Do not breathe in the powder or dust when mixing a dose of Metamucil to avoid this problem.
Common Side Effects
Like any fiber supplement, Metamucil can cause gas and bloating, according to UMMC. Its psyllium content may also cause stomach pain, nausea, vomiting and diarrhea. If you have kidney disease, diabetes, heart disease, high blood pressure or rectal bleeding, you are at a higher risk of complications if you take products that contain psyllium. Talk to your doctor before taking Metamucil.
Because of the psyllium content, Metamucil may reduce or delay the absorption of some medications, which could impair their effectiveness or increase the risk of side effects. You may be able to reduce this problem by not taking Metamucil at the same time as your other medications, according to UMMC. Try to take Metamucil at least an hour before taking other drugs or at least two hours after taking your medication. Talk to your doctor or pharmacist before taking Metamucil if you are taking antidepressants, seizure medication, anti-cholesterol medication, diabetes drugs, digoxin, lithium, aspirin, nitrofurantoin, tetracycline or a diuretic.