What is the best medicine to take for severe constipation?

October 12, 2025 •

4 min read

According to the National Institute of Diabetes and Digestive and Kidney Diseases, constipation affects approximately 16% of adults in the United States, with a higher rate among those over 60. When diet and lifestyle changes are not enough, determining what is the best medicine to take for severe constipation requires understanding the different types of laxatives available and consulting a healthcare professional.

Quick Summary

Different medications for severe constipation work through various mechanisms, from softening stool to stimulating intestinal muscles. The best option depends on the cause and severity, with over-the-counter choices like osmotic laxatives often recommended first, followed by prescription drugs for chronic or complex cases. Always seek medical advice before starting treatment.

Key Points

Start with OTC Options: For non-chronic severe constipation, osmotic laxatives like MiraLAX or stimulant laxatives like Dulcolax are commonly used and often effective.
Consider Prescription for Chronic Issues: If over-the-counter options fail, or for chronic conditions like CIC or IBS-C, prescription medications such as Linzess, Motegrity, or Trulance may be necessary.
Opioid-Induced Constipation Requires Special Treatment: Standard laxatives are often ineffective for constipation caused by opioids; specialized prescription medications called PAMORAs (e.g., Movantik, Relistor) are typically required.
Consult a Healthcare Provider for Guidance: The ideal treatment depends on the underlying cause, so always consult a doctor or pharmacist to determine the safest and most effective medicine for your specific situation.
Be Cautious with Stimulant Laxatives: Stimulant laxatives are for short-term use only and should not be relied upon long-term, as this can lead to dependency.
Prioritize Lifestyle Changes: Even for severe constipation, foundational changes like increasing fluid and fiber intake are essential and should be implemented alongside medication.

For individuals struggling with severe or chronic constipation, understanding the different types of medications is key to finding effective relief. While many cases of occasional constipation can be managed with simple dietary and lifestyle adjustments, more serious or persistent issues may require medication. The "best" medicine is subjective and depends on factors like the underlying cause, symptom severity, and individual health profile.

Over-the-Counter Options for Severe Constipation

When severe constipation is not chronic and does not respond to basic measures like increasing fiber and fluids, over-the-counter (OTC) laxatives are often the next step. A healthcare provider or pharmacist can help you select the most appropriate type.

Osmotic Laxatives

These are often a first-line therapy because they are highly effective and generally well-tolerated.

How they work: Osmotic laxatives pull water from the rest of the body into the colon, which softens the stool and makes it easier to pass.
Examples: Polyethylene glycol (PEG), such as MiraLAX, is a common example. Magnesium hydroxide (Milk of Magnesia) and magnesium citrate are saline laxatives that are also osmotics and work more quickly.
Considerations: Drinking plenty of water is essential for these to work effectively and to prevent dehydration.

Stimulant Laxatives

Stimulant laxatives are a powerful and fast-acting option for short-term relief of severe constipation.

How they work: They cause the muscles in the large intestine to contract, forcing stool to move through the colon more quickly.
Examples: Bisacodyl (Dulcolax) and senna (Senokot, Ex-Lax) are common oral stimulants. Bisacodyl is also available as a faster-acting suppository.
Considerations: These should be used sparingly and not for long-term management, as overuse can lead to dependency.

Suppositories and Enemas

For more immediate relief, rectal options are available and often work within minutes to an hour.

How they work: Glycerin suppositories work osmotically, drawing water into the rectum. Stimulant suppositories (like bisacodyl) trigger local muscle contractions. Enemas, such as mineral oil, lubricate the stool.
Considerations: These are typically for occasional use, not for chronic management.

Prescription Medications for Chronic or Severe Constipation

If OTC options and lifestyle changes are unsuccessful, or if constipation is linked to an underlying condition like Irritable Bowel Syndrome with Constipation (IBS-C), a healthcare provider may prescribe a more targeted medication.

Secretagogues

These drugs increase fluid secretion in the intestines to soften stool and promote bowel movements.

Linaclotide (Linzess): A once-daily capsule approved for adults with chronic idiopathic constipation (CIC) and IBS-C. It works by stimulating intestinal fluid secretion and can also help relieve abdominal pain.
Lubiprostone (Amitiza): This medication increases fluid in the gut by activating chloride channels and is used for CIC, IBS-C in women, and opioid-induced constipation (OIC).
Plecanatide (Trulance): A daily tablet for adults with CIC and IBS-C, it increases intestinal fluid and movement.

Serotonin Agonists

These medications increase intestinal muscle activity to accelerate transit time.

Prucalopride (Motegrity): Approved for adults with CIC, this drug stimulates contractions in the GI tract to move stool along. Common side effects can include headache and nausea.

Treatments for Opioid-Induced Constipation (OIC)

OIC is a specific type of severe constipation caused by opioid pain medication. Regular laxatives are often ineffective, requiring specific drugs that counteract the opioid's effect on the bowel.

PAMORAs (Peripherally Acting Mu-Opioid Receptor Antagonists): These drugs block opioids' constipating effects in the gut without affecting pain relief in the brain. Examples include naloxegol (Movantik), naldemedine (Symproic), and methylnaltrexone (Relistor).

Comparison of Constipation Medications


Type of Medication	Examples (Brand Name)	Mechanism of Action	Time to Effect	Best for...
Bulk-Forming Laxatives	Psyllium (Metamucil), Methylcellulose (Citrucel)	Adds fiber to stool, absorbing water to increase bulk and soften stool	12–72 hours	Mild to moderate, non-chronic constipation; often recommended first
Osmotic Laxatives	Polyethylene glycol (MiraLAX), Milk of Magnesia	Draws water into the colon to soften stool and stimulate bowel movements	1–3 days (PEG), 30 min–6 hours (Milk of Magnesia)	Chronic constipation, including severe cases
Stimulant Laxatives	Bisacodyl (Dulcolax), Senna (Senokot)	Stimulates intestinal muscles to contract and push stool forward	6–12 hours (oral), 15–60 mins (suppository)	Occasional, immediate relief for severe constipation
Secretagogues	Linaclotide (Linzess), Lubiprostone (Amitiza)	Increases intestinal fluid secretion	Varies by drug (usually days)	Chronic idiopathic constipation (CIC) and Irritable Bowel Syndrome with Constipation (IBS-C)
Serotonin Agonists	Prucalopride (Motegrity)	Increases intestinal movement	Varies by drug	Chronic idiopathic constipation (CIC)
PAMORAs	Naloxegol (Movantik), Methylnaltrexone (Relistor)	Blocks opioid's constipating effect in the gut	Varies by drug	Opioid-induced constipation (OIC)

Conclusion

There is no single "best" medication for severe constipation, as the ideal treatment depends on the cause, severity, and individual patient factors. A stepped approach, beginning with lifestyle modifications, followed by OTC options, and progressing to prescription medications for chronic or complex cases, is often recommended. Osmotic laxatives like MiraLAX are frequently a first choice for more severe cases that don't respond to bulk-forming agents, while stimulant laxatives can provide faster, short-term relief. For truly chronic or condition-related severe constipation, prescription options such as Linzess or Motegrity offer more targeted relief. Crucially, anyone experiencing severe, persistent, or recurring constipation should consult a healthcare provider to receive a proper diagnosis and rule out any serious underlying conditions before starting a treatment regimen. For more detailed information on specific laxatives, refer to sources like the Mayo Clinic.

When to see a doctor

While many people can manage constipation at home, you should see a doctor if your symptoms are severe, persistent, or accompanied by other concerning signs. Seek medical advice if you experience:

A sudden change in bowel habits.
Unexplained weight loss.
Rectal bleeding or blood in your stool.
Severe abdominal pain.
Constipation that does not improve with conservative measures.

A doctor can evaluate your condition and help determine the most effective and safe treatment plan, which may include prescription medications if needed.

Frequently Asked Questions

There is no single 'strongest' OTC medication, as different types work differently. Stimulant laxatives (like Dulcolax or Senokot) are powerful and work quickly for short-term relief, while osmotic laxatives (like MiraLAX) are highly effective for chronic use by drawing water into the colon.

You should consider a prescription medication if over-the-counter remedies and lifestyle changes do not relieve your severe or chronic constipation. This is especially true for those with underlying conditions like IBS-C or opioid-induced constipation.

Yes. Occasional constipation is often managed with bulk-forming or osmotic laxatives. Severe, chronic, or condition-related constipation may require stronger or more specialized prescription medications, which are not suitable for occasional use.

The speed varies: rectal suppositories (glycerin or bisacodyl) work within minutes to an hour, oral stimulant laxatives (bisacodyl) take 6–12 hours, osmotic laxatives (MiraLAX) can take 1–3 days, and bulk-forming agents (Metamucil) can take 12–72 hours.

Diet and lifestyle are the foundation of any constipation treatment. Increasing your intake of fiber and fluids, along with regular exercise, can significantly improve bowel function and should be a part of your management plan, even when medication is necessary.

Long-term daily use of stimulant laxatives is not recommended. It can lead to dependency, where your body may lose its natural ability to have a bowel movement without the medication.

Opioid-induced constipation is often treated with specific prescription medications called PAMORAs (peripherally acting mu-opioid receptor antagonists). Examples include naloxegol (Movantik), naldemedine (Symproic), and methylnaltrexone (Relistor).