A Fleet enema is a ready-to-use, over-the-counter rectal laxative that relieves constipation by drawing water into the lower bowel to soften stool and trigger a bowel movement. It typically works within 1 to 5 minutes, making it one of the fastest-acting constipation remedies available. The product comes in a pre-filled, disposable squeeze bottle with a lubricated tip, designed for a single use.
How a Fleet Enema Works
The standard Fleet saline enema contains two forms of sodium phosphate dissolved in water. When this solution enters the rectum, it creates a concentrated salt environment that pulls water out of the surrounding colon tissue and into the bowel. This process, called osmosis, softens hard stool and increases the volume of fluid in the lower intestine. At the same time, the physical pressure of the added fluid triggers a natural reflex that stimulates the urge to have a bowel movement.
Each adult dose delivers 118 mL (about 4 ounces) of solution. That’s a small volume, which is part of why Fleet enemas are considered more convenient and less uncomfortable than larger-volume enemas used in clinical settings.
Different Types of Fleet Enemas
The most common version is the saline (sodium phosphate) enema, but Fleet makes several other formulations:
- Saline enema: The standard product. Uses sodium phosphate to draw water into the bowel. Works in 1 to 5 minutes.
- Mineral oil enema: A lubricant-based enema that coats and softens stool so it slides out more easily. This version avoids phosphate salts entirely.
- Bisacodyl enema: A stimulant laxative delivered rectally. Rather than pulling water into the bowel, it directly stimulates the muscles of the colon to contract.
When people say “Fleet enema” without specifying, they almost always mean the saline version.
How to Use One
The bottle comes with a pre-lubricated tip designed to make insertion easier. You lie on your left side with your right knee bent toward your chest. After removing the protective cap, you gently insert the tip into the rectum, then slowly squeeze the bottle until most of the liquid is inside. You don’t need to empty the bottle completely.
After insertion, try to hold the solution for as long as you comfortably can. Most people feel a strong urge to go within a few minutes. Stay near a bathroom, because the effect can come on quickly and with some urgency. Cramping during or just after use is normal and usually passes once you have a bowel movement.
Who Should Avoid Phosphate Enemas
The sodium phosphate in Fleet enemas is safe for most adults when used as directed, but it poses real risks for certain people. The phosphate in the solution gets partially absorbed through the intestinal lining and must be cleared by the kidneys. If your kidneys can’t process it efficiently, phosphate can build up in the blood and cause dangerous shifts in your body’s electrolyte balance, including drops in calcium and potassium levels.
People with kidney disease should avoid phosphate-based enemas. Nephrology guidelines for chronic kidney disease patients list sodium phosphate laxatives in the “do not use” category because of the risk of phosphate accumulation. People with heart failure or those on medications that affect kidney function or fluid balance also face higher risk.
Elderly adults are particularly vulnerable. Slower gut motility means the solution may sit in the bowel longer, allowing more phosphate to be absorbed. Combined with age-related kidney decline and common medications like diuretics, this can lead to serious electrolyte disturbances. Research published in JAMA Internal Medicine found that sodium phosphate products can induce high phosphate levels, low calcium, and low potassium, a combination that can affect heart rhythm.
The One-Bottle-Per-Day Rule
In January 2014, the FDA issued a safety warning that using more than one sodium phosphate enema in a 24-hour period could cause rare but serious harm to the heart and kidneys. This applies even to healthy adults. The warning came after reports of hospitalizations and, in rare cases, deaths linked to repeat dosing or use by high-risk individuals.
A survey of gastroenterologists found that only 24% knew the maximum recommended dose was one bottle per 24 hours, which suggests this limit isn’t as widely understood as it should be, even among medical professionals. If a single enema doesn’t produce results, the answer is not a second dose. It’s a call to your doctor to discuss alternatives.
Use in Children
Fleet makes a pediatric version called Pedia-Lax, which contains half the volume of the adult product (59 mL per dose). Children ages 5 to 11 can use one full pediatric bottle per day. Children ages 2 to 4 use only half a bottle, which means removing about two tablespoons of liquid before administering. Children under 2 should never be given a phosphate enema. Their smaller body size makes phosphate toxicity a serious and potentially life-threatening risk.
Common Side Effects
Most people experience mild cramping and a sense of urgency, both of which resolve quickly. Some bloating or gas afterward is also normal. These effects are short-lived because the enema only acts on the lower portion of the colon.
More concerning symptoms, which are uncommon with single-dose use but possible, include dizziness, muscle weakness, irregular heartbeat, or a tingling sensation. These can signal electrolyte imbalances caused by excessive phosphate absorption. If you experience any of these after using a Fleet enema, that warrants prompt medical attention.
When a Fleet Enema Makes Sense
Fleet enemas are designed for occasional, short-term relief of constipation. They’re also commonly used before medical procedures like sigmoidoscopies or rectal surgeries, where the lower bowel needs to be clear. Their speed (results in minutes, not hours) makes them useful when you need quick relief that oral laxatives can’t provide.
They’re not meant for regular or long-term use. Repeated use can lead to dependence, where the bowel becomes less responsive to normal signals. If you find yourself reaching for enemas more than occasionally, that’s a sign the underlying cause of constipation needs to be addressed rather than bypassed. For people with kidney disease, heart conditions, or electrolyte disorders, a mineral oil enema or another phosphate-free option is a safer choice.