Fiber-Lax 500mg Tablets
It is used to treat constipation.
Drug Class
Laxative
Pharmacologic Class
Bulk-forming laxative; synthetic hydrophilic polymer
Pregnancy Category
Category B
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Polycarbophil is a type of fiber supplement that helps relieve constipation by absorbing water in your intestines. This makes your stool softer and bulkier, which helps it pass more easily. It's important to drink plenty of water when taking this medication.
How to Use This Medicine
Taking Your Medication Correctly
To ensure you get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with a full glass of water.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so by your pharmacist. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are drug take-back programs available in your area.
What to Do If You Miss a Dose
If you take your medication regularly, take a missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses. If you take your medication as needed, do not take it more frequently than directed by your doctor.
To ensure you get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with a full glass of water.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so by your pharmacist. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are drug take-back programs available in your area.
What to Do If You Miss a Dose
If you take your medication regularly, take a missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses. If you take your medication as needed, do not take it more frequently than directed by your doctor.
Lifestyle & Tips
- Drink at least 8 ounces (a full glass) of water or other fluid with each dose of polycarbophil.
- Maintain adequate fluid intake throughout the day to prevent dehydration and ensure the medication works effectively.
- Increase dietary fiber intake through fruits, vegetables, and whole grains.
- Engage in regular physical activity, as exercise can help promote bowel regularity.
- Do not take this medication if you have sudden changes in bowel habits lasting more than 2 weeks, abdominal pain, nausea, or vomiting, unless directed by a doctor.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
1000 mg (two 500 mg tablets) 1 to 4 times daily
Dose Range:
1000 - 4000 mg
Condition-Specific Dosing:
constipation:
1000 mg (two 500 mg tablets) 1 to 4 times daily, with at least 8 oz (240 mL) of water or other fluid. Do not exceed 4000 mg in 24 hours.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Children 6-11 years: 500 mg (one 500 mg tablet) 1 to 3 times daily, with at least 8 oz (240 mL) of water or other fluid. Do not exceed 1500 mg in 24 hours. Consult a physician for children under 6 years.
Adolescent:
Adolescents 12 years and older: Same as adult dosing.
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed
Dialysis:
No specific considerations as polycarbophil is not systemically absorbed.
Hepatic Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed
Pharmacology
Mechanism of Action
Polycarbophil is a synthetic, hydrophilic polyacrylic resin that is not absorbed systemically. It absorbs water in the gastrointestinal tract, forming a bulky, emollient gel that increases the volume and moisture content of the stool. This increased bulk stimulates peristalsis and facilitates bowel evacuation, promoting a soft, regular bowel movement.
Pharmacokinetics
Absorption:
Bioavailability:
Virtually 0%
Tmax:
Not applicable (not absorbed)
FoodEffect:
No significant food effect on efficacy, but should be taken with adequate fluid.
Distribution:
Vd:
Not applicable (not absorbed)
ProteinBinding:
Not applicable (not absorbed)
CnssPenetration:
No
Elimination:
HalfLife:
Not applicable (not absorbed)
Clearance:
Not applicable (not absorbed)
ExcretionRoute:
Fecal (unchanged)
Unchanged:
Nearly 100%
Pharmacodynamics
OnsetOfAction:
12 to 72 hours (1 to 3 days)
PeakEffect:
Not distinctly applicable; effect builds over 1-3 days of consistent use.
DurationOfAction:
Continuous with regular dosing; effect persists as long as product is used.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Chest pain or pressure
Upset stomach or vomiting
Stomach pain
Other Possible Side Effects
Like all medications, this drug can cause side effects. However, many people do not experience any side effects or only have mild ones. If you have any side effects that bother you or do not go away, contact your doctor for advice. Not all possible side effects are listed here. If you have questions or concerns about side effects, discuss them with your doctor.
Reporting Side Effects
You can report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch. Your doctor can also provide guidance on managing side effects and offer medical advice.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Chest pain or pressure
Upset stomach or vomiting
Stomach pain
Other Possible Side Effects
Like all medications, this drug can cause side effects. However, many people do not experience any side effects or only have mild ones. If you have any side effects that bother you or do not go away, contact your doctor for advice. Not all possible side effects are listed here. If you have questions or concerns about side effects, discuss them with your doctor.
Reporting Side Effects
You can report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch. Your doctor can also provide guidance on managing side effects and offer medical advice.
Seek Immediate Medical Attention If You Experience:
- Severe abdominal pain, cramping, or bloating
- Nausea or vomiting
- Difficulty swallowing the tablet
- Choking sensation after taking the tablet
- Rectal bleeding
- No bowel movement after 3 days of use
- Worsening constipation
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction and its symptoms.
If you experience difficulty swallowing.
* If you have a history of certain health issues, including:
+ Bowel obstruction
+ Abdominal pain
+ Upset stomach
+ Rectal bleeding
+ Vomiting
+ Changes in bowel habits that persist for more than 2 weeks
This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health problems with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without consulting your doctor first.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction and its symptoms.
If you experience difficulty swallowing.
* If you have a history of certain health issues, including:
+ Bowel obstruction
+ Abdominal pain
+ Upset stomach
+ Rectal bleeding
+ Vomiting
+ Changes in bowel habits that persist for more than 2 weeks
This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health problems with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without consulting your doctor first.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
To minimize the risk of choking, it is crucial to take this drug with a sufficient amount of fluids. Insufficient fluid intake may cause the drug to swell and potentially block your throat, leading to choking. If you have concerns, discuss them with your doctor.
This medication can interfere with the absorption of other drugs, reducing their effectiveness. If you are taking other medications, consult your doctor or pharmacist to determine if you should take them at a different time than this drug.
Do not use this medication for more than 1 week without explicit instruction from your doctor.
If you experience rectal bleeding or do not have a bowel movement after using this drug, consult your doctor promptly.
Unless advised by your doctor, avoid using other laxatives or stool softeners in conjunction with this medication.
If you are pregnant, planning to become pregnant, or are breast-feeding, inform your doctor. It is necessary to discuss the potential benefits and risks of this medication to both you and your baby.
To minimize the risk of choking, it is crucial to take this drug with a sufficient amount of fluids. Insufficient fluid intake may cause the drug to swell and potentially block your throat, leading to choking. If you have concerns, discuss them with your doctor.
This medication can interfere with the absorption of other drugs, reducing their effectiveness. If you are taking other medications, consult your doctor or pharmacist to determine if you should take them at a different time than this drug.
Do not use this medication for more than 1 week without explicit instruction from your doctor.
If you experience rectal bleeding or do not have a bowel movement after using this drug, consult your doctor promptly.
Unless advised by your doctor, avoid using other laxatives or stool softeners in conjunction with this medication.
If you are pregnant, planning to become pregnant, or are breast-feeding, inform your doctor. It is necessary to discuss the potential benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Severe abdominal distension
- Intestinal obstruction (rare, but possible with insufficient fluid intake)
- Severe bloating
- Cramping
What to Do:
Discontinue use immediately. Ensure adequate fluid intake. If symptoms are severe or persistent, seek immediate medical attention or call a poison control center (1-800-222-1222 in the US).
Drug Interactions
Moderate Interactions
- Tetracyclines (e.g., doxycycline, minocycline): May decrease absorption. Separate administration by at least 2 hours.
- Digoxin: May decrease absorption. Separate administration by at least 2 hours.
- Warfarin: May decrease absorption. Separate administration by at least 2 hours.
- Oral contraceptives: Potential for decreased absorption. Separate administration by at least 2 hours.
- Other oral medications: May decrease absorption of other concurrently administered oral medications. Advise patients to take other medications at least 2 hours before or 2 hours after polycarbophil.
Monitoring
Baseline Monitoring
Bowel history (frequency, consistency, straining)
Rationale: To establish baseline constipation severity and assess treatment efficacy.
Timing: Prior to initiation of therapy
Hydration status
Rationale: Adequate fluid intake is crucial for polycarbophil's action and to prevent impaction.
Timing: Prior to initiation of therapy
Routine Monitoring
Bowel movement frequency and consistency
Frequency: Daily
Target: Regular, soft, formed stools
Action Threshold: No bowel movement after 3 days of use, worsening constipation, or new abdominal pain.
Fluid intake
Frequency: Daily
Target: At least 8 oz (240 mL) with each dose, and adequate daily hydration.
Action Threshold: Signs of dehydration or insufficient fluid intake.
Abdominal symptoms (pain, bloating, distension)
Frequency: Daily
Target: Absence of significant discomfort
Action Threshold: New or worsening severe abdominal pain, bloating, or distension; signs of obstruction.
Symptom Monitoring
- Relief of constipation
- Abdominal discomfort or cramping
- Bloating
- Flatulence
- Signs of intestinal obstruction (e.g., severe abdominal pain, nausea, vomiting, inability to pass gas or stool)
- Rectal bleeding
Special Patient Groups
Pregnancy
Polycarbophil is generally considered safe for use during pregnancy due to its lack of systemic absorption. It is often recommended as a first-line treatment for constipation in pregnant women.
Trimester-Specific Risks:
First Trimester:
Low risk
Second Trimester:
Low risk
Third Trimester:
Low risk
Lactation
Polycarbophil is considered safe for use during lactation as it is not absorbed systemically by the mother and therefore cannot be transferred into breast milk.
Infant Risk:
L1 (Safest - compatible with breastfeeding)
Pediatric Use
Use in children should be under the guidance of a healthcare professional, especially for those under 6 years of age. Ensure adequate fluid intake to prevent choking or impaction. Dosing is age-dependent.
Geriatric Use
Generally safe for use in the elderly. However, older adults may be more susceptible to dehydration, so ensuring adequate fluid intake is particularly important. Start with the lowest effective dose.
Clinical Information
Clinical Pearls
- Always take polycarbophil with a full glass (at least 8 oz or 240 mL) of water or other fluid to prevent choking or esophageal/intestinal obstruction.
- Effects are not immediate; it may take 1 to 3 days for a bowel movement to occur.
- This product is for occasional constipation and should not be used for more than 7 days unless directed by a doctor.
- Advise patients to separate administration of polycarbophil from other oral medications by at least 2 hours to avoid potential interference with absorption.
- Encourage patients to maintain a high fluid intake throughout the day, not just with doses, to maximize efficacy and prevent adverse effects.
- Not for use in patients with suspected intestinal obstruction, fecal impaction, or undiagnosed abdominal pain.
Alternative Therapies
- Dietary fiber (e.g., psyllium, methylcellulose, wheat dextrin)
- Osmotic laxatives (e.g., polyethylene glycol, lactulose, magnesium hydroxide)
- Stool softeners (e.g., docusate sodium)
- Stimulant laxatives (e.g., bisacodyl, senna) - generally not for long-term use
- Lubricant laxatives (e.g., mineral oil)
Cost & Coverage
Average Cost:
$5 - $20 per 30-100 tablets
Generic Available:
Yes
Insurance Coverage:
Over-the-counter (OTC) product; generally not covered by insurance unless prescribed by a physician and deemed medically necessary.
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.