Bulk-Forming Agents (Fiber Supplements)
These are the first-line for most people with constipation. They are very safe and cause little side effects. For these to work, you must drink enough water and take it like a supplement, everyday.
How do they work: Bulks stool and increases water content while stimulating the bowels to contract
How fast do they work: 12–72 hours
Osmotic Laxatives
These are used when you are really struggling and fiber isn't enough. Some of these are what patients use before getting a colonoscopy because they really flush everything out. There are two groups of osmotic laxatives including "Saline" and "Non-saline"
How do they work: Draw water straight into your colon. This softens your stool and makes your bowels move faster to get rid of everything in them
How fast do they work: 30 minutes to 6 hours
Saline Osmotics
Non-saline Osmotics
- Polyethylene glycol (PEG) (MiraLAX, GoLYTELY)
Stimulant Laxatives
These are no good for long-term control, but they can help in a pinch. They can cause cramping and more side effects if used for too long.
How do they work: Stimulate enteric nerves and colonic contraction
How fast do they work: 6–12 hours oral; faster rectally
- Examples:
- Senna (Senokot)
- Bisacodyl (Dulcolax, oral or suppository)
- Castor oil (rarely used)
Stool Softeners (Emollients)
These help water break into your stool to literally soften it. These are common for people to use after surgery or for those taking pain medications that cause constipation. If you are very constipated, these won't help as much. They make the stool softer, but don't help get rid of it.
How do they work: Make it easier for water and fat to enter stool, literally "Softening" the stool
How fast do they work: 12 – 72 hours
- Examples:
- Docusate sodium (Colace)
- Docusate calcium