How Long Does It Take for Laxatives to Work? - GoodRx (2024)

Constipation can be annoying and uncomfortable. And if you’re constipated, you probably want relief as soon as possible. So it’s helpful to know how long different laxatives take to work. Some laxatives work faster than others — and while fast relief can be a good thing, it can also come with unwanted side effects that have you looking for a gentler option. Let’s explore the different over-the-counter (OTC) laxatives available and how long they take to work.

What are laxatives?

Laxatives are a group of medications used to treat constipation. They’re available as many different OTC brand-name and generic products. They also come in different forms, with both oral (tablets, capsules, and liquids) and rectal (enemas and suppositories) options.

Each type of laxative works differently to help you achieve a bowel movement. So they each take a different amount of time to start working. OTC laxatives can provide relief within 1 minute to 3 days depending on which type you use. And some products may not be the best choice for everyone.

When should you use a laxative?

If you’re having bowel movements less than 3 times per week, you may be constipated. Typically, it’s recommended to try adjusting your lifestyle habits to help with constipation before taking a laxative. This can include things like adding fiber to your diet, drinking more water, and exercising regularly. But if these changes don’t relieve your constipation, it may be time to try an OTC laxative.

Some laxatives work faster than others. But the laxative you choose can depend on several other factors. These include how you want to take it (oral or rectal), if you’re taking other medications, and if you have any underlying health issues.

Relief within minutes

Rectal enemas and suppositories are the fastest acting laxatives available. These include saline and mineral oil enemas as well as glycerin and bisacodyl rectal suppositories. Common OTC products in this group include Fleet enema, Pedia-Lax, and the Magic Bullet.

Rectal enemas should provide almost instant relief, as they work within 5 to 10 minutes. If it’s been more than 30 minutes and you haven’t gone to the bathroom, it’s best to seek medical care. Solid rectal suppositories can take a little longer — about 30 to 60 minutes — to work.

How long the effects last vary from person to person. You may only have one bowel movement and be done. Or it may take an hour or more to fully empty your system. So it’s best to stay near a bathroom for at least an hour or two after giving yourself a rectal laxative. You shouldn’t use more than one rectal laxative in a 24-hour period. And you shouldn’t use them for more than 2 days in a row without talking to a healthcare professional.

Pros

Rectally administered laxatives work quickly. They may also be useful for people who have difficulty swallowing. Another advantage to these medications is that there are OTC formulations available for both adults and children aged 2 years and over.

Cons

The fast onset of these laxatives comes with a downside. They often cause stomach cramping and diarrhea. They may also cause rectal irritation. It’s often also more difficult or uncomfortable for some people to use a rectal product than it is to take medication by mouth. Enemas require squeezing liquid into the rectum. And suppositories, which are usually solid and bullet-shaped, must be inserted properly to work.

Saline enemas might not be the best choice for people who are limiting their sodium intake or who have kidney or heart problems. Medications that are formulated for rectal use can also be dangerous if accidentally swallowed, so it’s important to only use them as directed and store them securely.

Relief within hours

The fastest-working oral laxatives include:

• Mineral oil

• Saline laxatives, such as magnesium hydroxide and magnesium citrate

• Stimulant laxatives, such as bisacodyl and senna tablets

Common OTC products in this group include Milk of Magnesia, Dulcolax, and Senokot.

Saline laxatives work within 30 minutes to 6 hours. Mineral oil, bisacodyl, and senna can take 6 to 12 hours to work, so they’re often taken at bedtime in hopes of a bowel movement in the morning.

These laxatives generally work as they move through your digestive system, so once you pass them, their effects will stop. And their effects are typically gentler than rectal laxatives. But it’s best to stay near a bathroom until you know how your system responds.

Pros

These laxatives typically work in less than 12 hours. And they’re taken orally, which is more comfortable for most people. Most of these laxatives are safe for children as well as adults. But read the package labeling first to be sure.

Cons

Like the rectally administered laxatives, oral laxatives can cause cramping and diarrhea.

Oral saline laxatives can affect the way that some medications are absorbed in the body. They may also not be the best choice for people with kidney problems.

You shouldn’t take bisacodyl within an hour of drinking milk or taking antacids.

Taking mineral oil by mouth can be dangerous for people with difficulty swallowing. There have been reports of it causing pneumonia if it’s accidentally inhaled into the lungs, which can happen if you cough while swallowing. Fast-working oral laxatives are also generally not first-choice products for constipation relief while pregnant.

If you’re taking other medications, have difficulty swallowing, or are pregnant, be sure to speak with your pharmacist or prescriber to make sure you’re choosing an OTC laxative product that’s safe for you.

Relief within days

There are three types of laxatives that take longer (12 hours to 3 days) to work:

• Bulk-forming laxatives (fiber products) such as psyllium (Metamucil) and methylcellulose (Citrucel)

• Stool softeners, such as docusate sodium (Colace)

• Osmotic laxatives, such as polyethylene glycol 3350 (Miralax)

These types of laxatives don’t typically cause the same urgency as the faster-acting laxatives do. So they’re less likely to interfere with your daily activities. And all long-acting laxatives will work better if you’re well hydrated, so be sure to drink plenty of fluids each day.

Pros

While these laxatives take longer to work, they’re usually more gentle and have fewer side effects than faster-acting laxatives.

Miralax comes as a powder that can be mixed with any beverage. It’s also available in pre-measured packets. This may be a better option for people who have trouble swallowing capsules or tablets.

Stool softeners are available in capsule, tablet, and liquid forms and have no known interactions with other medications.

Bulk-forming laxatives are generally considered safe for long-term use. They can also be helpful for ongoing problems such as irritable bowel syndrome or hemorrhoids.

All three of these products are also considered safe for children or during pregnancy in most cases.

Cons

These types of laxatives generally take longer to work. And although they cause fewer side effects than other laxatives, they can still cause some bloating, gas, or cramping.

Miralax might not be the best choice if you have kidney problems. And all three of these types of laxatives may not be a good choice for people who are restricting their fluid intake. This is because they all require you to drink a lot of fluids for them to work well.

Bulk-forming and osmotic laxatives might affect the way certain medications are absorbed. Be sure to talk to your prescriber or pharmacist if you’re taking other medications and are in need of an OTC laxative.

What should you do if a laxative isn’t working?

If your constipation isn’t relieved with OTC laxatives, it could mean that you have a more serious condition going on. One possibility is a bowel obstruction. This is caused when something’s preventing food from moving through your gut properly and things get backed up. If this goes on for too long it can be a medical emergency — and can even require surgery in some cases. Other health conditions could also lead to hard-to-treat constipation, including colon or rectal cancer.

Seek medical care right away if you have constipation along with any of the following symptoms:

• Severe stomach cramping or pain

• Nausea and vomiting

• Inability to pass gas

• Blood in your stool

• Unexpected weight loss

Is it possible to use laxatives too much?

Yes, it’s possible to use laxatives too much.

Always follow the instructions on the package about proper laxative usage. Most OTC laxatives recommend contacting a healthcare professional if you need to use them for more than 7 days at a time. That’s because you could have another problem that’s causing your constipation. In this case, it’s a good idea to seek medical care to determine what’s going on.

Overuse can result in dehydration and an imbalance in your electrolytes. This can contribute to heart and kidney problems. Talk to a healthcare professional if you’re finding that you need to use laxatives regularly.