How laxatives relieve constipation

Laxatives work in different ways. How well each laxative type works varies from person to person. In general, fiber supplements are the gentlest on your body. These also are called bulk-forming laxatives. Metamucil and Citrucel fall into this category. Here are some examples of different laxatives. Even though many laxatives are available without a prescription, it's best to talk to your healthcare team first. They can help decide the safest kind of laxative for you.

Type of laxative (brand examples)	How they work	Side effects
Oral osmotics (Phillips' Milk of Magnesia, MiraLAX, Magnesium Hydroxide, Polyethylene glycol)	Draw water into the colon to allow easier passage of stool	Bloating, cramping, diarrhea, nausea, gas, increased thirst
Oral bulk formers (Benefiber, Citrucel, FiberCon, Metamucil)	Absorb water to form soft, bulky stool, prompting normal contraction of intestinal muscles	Bloating, gas, cramping or increased constipation if not taken with enough water
Oral stool softeners (Colace, Surfak, Docusate Calcium)	Add moisture to stool to soften stool, allowing strain-free bowel movements	Electrolyte imbalance if used for a long time
Oral stimulants (Dulcolax, Senokot Bisacodyl, Senna/Sennosides)	Trigger rhythmic contractions of intestinal muscles to eliminate stool	Belching, cramping, diarrhea, nausea, urine discoloration with senna and cascara derivatives
Rectal suppositories (Dulcolax, Bisacodyl, Pedia-Lax)	Trigger rhythmic contractions of intestinal muscles and soften stool	Rectal irritation, diarrhea, cramping

Oral laxatives can change how your body absorbs some medicines and nutrients. After long-term use, some laxatives can lead to an electrolyte imbalance or other serious health issues. Electrolytes include calcium, chloride, potassium, magnesium and sodium. They regulate several body functions. An imbalance of electrolytes can cause heart rhythm changes, weakness, confusion and seizures.