Ex-Lax is an over-the-counter stimulant laxative used to relieve occasional constipation. Its active ingredient is sennosides, a compound derived from the senna plant that triggers the colon to push stool through more quickly. It comes in regular strength (15 mg sennosides per tablet) and maximum strength (25 mg per tablet), as well as chewable chocolate pieces.
How Ex-Lax Works in Your Body
When you swallow an Ex-Lax tablet, the sennosides travel to your colon largely intact. Bacteria in your gut then convert them into an active compound called rhein anthrone, which does two things. First, it activates immune cells in the colon wall that release a signaling molecule (prostaglandin E2), which reduces how much water your colon absorbs from stool. Second, it slows contractions in the upper colon while speeding up movement through the lower colon, pushing contents toward the exit faster.
The net effect: stool stays softer because less water is pulled out of it, and it moves through more quickly. Most people can expect a bowel movement within 6 to 12 hours of taking Ex-Lax, which is why many people take it at bedtime for morning relief.
Available Forms and Dosing
Ex-Lax is sold as standard tablets, maximum strength tablets, and chocolate chewable pieces. The tablets should be swallowed whole with a full glass of water. The chocolate pieces need to be chewed before swallowing. You should not combine different forms at the same time, as this increases the risk of taking too much.
For adults and children 12 and older, the recommended dose is 2 tablets once or twice daily. Children ages 6 to 11 can take 1 tablet once or twice daily. It is not intended for children under 6 without a doctor’s guidance, and it should not be used for longer than one week.
Common Side Effects
Because Ex-Lax is a stimulant laxative, it directly irritates the colon wall to produce its effect. That means cramping and abdominal discomfort are common, especially at higher doses. Other typical side effects include nausea, diarrhea, and belching. Senna can also discolor your urine to a yellowish-brown or reddish tint, which is harmless.
If you experience severe stomach pain, bloody stools, rectal bleeding, or dizziness, those are signs something more serious is going on and you should contact a healthcare provider promptly.
Risks of Using It Too Often
The one-week limit on the label exists for good reason. Long-term use of stimulant laxatives can create a cycle of dependency where your colon loses its ability to contract on its own, making constipation worse over time rather than better. Imaging studies of people who use stimulant laxatives chronically show loss of the normal folds in the colon wall, suggesting possible nerve or muscle damage to the intestinal lining.
Extended use also raises the risk of electrolyte imbalances. Your colon normally absorbs minerals like potassium, sodium, and magnesium from digested food. When stool moves through too quickly or contains too much water, those minerals get flushed out. Electrolyte imbalances can cause muscle weakness, confusion, irregular heartbeat, and in severe cases, seizures. This risk is particularly relevant for people who misuse laxatives as part of disordered eating patterns.
Who Should Avoid Ex-Lax
Ex-Lax is meant for occasional constipation relief, not for chronic digestive conditions. People with undiagnosed abdominal pain should not take it, since stimulant laxatives can worsen conditions like appendicitis or bowel obstruction. Anyone with a known sensitivity to senna or sennosides should avoid it entirely.
During pregnancy, stimulant laxatives like Ex-Lax are considered a second-line option, meaning fiber supplements and osmotic laxatives are generally preferred first. For breastfeeding, the picture is more reassuring. Multiple controlled studies have found that sennosides are undetectable in breast milk at normal doses, and infants showed no increase in loose stools or diarrhea compared to a placebo group. Standard doses of senna are considered acceptable during breastfeeding.
How Ex-Lax Compares to Other Laxatives
Laxatives fall into several categories, and understanding the differences helps you pick the right one for your situation.
- Bulk-forming laxatives (Metamucil, Benefiber) add fiber to stool so it holds more water and passes more easily. They’re the gentlest option and safe for daily use, but they take one to three days to work.
- Osmotic laxatives (MiraLAX, Milk of Magnesia) draw water into the colon. They typically work within one to three days and cause bloating and gas.
- Stool softeners (Colace) make stool easier to pass but don’t stimulate the colon. They’re mild and often used after surgery.
- Stimulant laxatives (Ex-Lax, Dulcolax, Senokot) directly trigger colon contractions. They work fastest, usually within 6 to 12 hours, but carry the highest risk of cramping and dependency with overuse.
Ex-Lax occupies the “fast but aggressive” end of that spectrum. If you’re dealing with occasional, stubborn constipation and need relief by the next morning, it fits that role well. For milder or recurring constipation, starting with fiber or an osmotic laxative puts less stress on your digestive system.