Acetaminophen 500mg Tablets
WARNING: Liver problems have happened with the use of acetaminophen. Sometimes, this has led to a liver transplant or death. Most of the time, liver problems happened in people taking more than 4,000 mg (milligrams) of acetaminophen in a day. People were also often taking more than 1 drug that had acetaminophen in it. If you have questions, talk with your doctor. @ COMMON USES: It is used to ease pain and fever.
Drug Class
Analgesic, Antipyretic
Pharmacologic Class
Para-aminophenol derivative
Pregnancy Category
Not available (FDA has phased out letter categories; generally considered low risk)
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Acetaminophen is a common medicine used to relieve pain and reduce fever. It works by affecting how your brain processes pain and regulates body temperature. It is not an anti-inflammatory drug like ibuprofen.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food.
Storing and Disposing of Your Medication
Keep your medication at room temperature, away from refrigeration and freezing. Store it in its original container, protected from light, with the lid tightly closed. Choose a dry location, avoiding the bathroom.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your normal schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than your doctor advises.
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food.
Storing and Disposing of Your Medication
Keep your medication at room temperature, away from refrigeration and freezing. Store it in its original container, protected from light, with the lid tightly closed. Choose a dry location, avoiding the bathroom.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your normal schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than your doctor advises.
Lifestyle & Tips
- Do not exceed the recommended dose. Taking too much can cause severe liver damage.
- Be aware of other medications (prescription or over-the-counter) that may also contain acetaminophen to avoid accidental overdose.
- Limit alcohol consumption while taking acetaminophen, especially if taking regularly, due to increased risk of liver damage.
- Store at room temperature away from moisture and heat.
Available Forms & Alternatives
Available Strengths:
- Acetaminophen 120mg Suppositories
- Acetaminophen 650mg Suppositories
- Acetaminophen 500mg Tablets
- Acetaminophen Child 160mg/5ml Susp
- Acetaminophen 500mg X/s Tablets
- Acetaminophen 500mg E/s Caplets
- Acetaminophen 160mg/5ml Solution
- Acetaminophen 325mg Tablets
- Acetaminophen 10mg/ml Inj, 100ml
- Acetaminophen 160mg/5ml Liquid
- Acetaminophen 500mg E/s Tablets
- Acetaminophen Child 160mg/5ml Susp
- Acetaminophen Infant 160mg/5ml Susp
- Acetaminophen 650mg ER Tablets
Dosing & Administration
Adult Dosing
Standard Dose:
500 mg every 4 to 6 hours as needed
Dose Range:
500 - 1000 mg
Condition-Specific Dosing:
maximum_daily_dose:
4000 mg (4g) in 24 hours; some sources recommend 3000 mg (3g) for chronic use or in patients with risk factors for hepatotoxicity.
Pediatric Dosing
Neonatal:
Not established (consult physician; typically 10-15 mg/kg/dose, not to exceed 60 mg/kg/day)
Infant:
10-15 mg/kg/dose every 4-6 hours as needed (max 5 doses/24 hours); consult physician for infants under 2 years.
Child:
10-15 mg/kg/dose every 4-6 hours as needed (max 5 doses/24 hours); do not exceed 75 mg/kg/day or 4000 mg/day, whichever is less.
Adolescent:
Same as adult dosing (10-15 mg/kg/dose, typically 500-1000 mg every 4-6 hours; max 4000 mg/day).
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
CrCl < 30 mL/min: Extend dosing interval to every 6-8 hours.
Dialysis:
Acetaminophen is dialyzable. Administer dose after dialysis.
Hepatic Impairment:
Mild:
Use with caution; consider reduced dose or extended interval.
Moderate:
Use with caution; consider reduced dose or extended interval (e.g., 500 mg every 6-8 hours). Avoid if possible.
Severe:
Contraindicated or use with extreme caution at significantly reduced doses (e.g., 500 mg every 8-12 hours) and close monitoring. Generally avoided due to risk of hepatotoxicity.
Pharmacology
Mechanism of Action
Acetaminophen (paracetamol) is thought to produce analgesia by inhibiting prostaglandin synthesis primarily in the central nervous system (CNS) and to a lesser extent, blocking pain impulse generation peripherally. Its antipyretic action is produced by inhibition of prostaglandin synthesis in the hypothalamus, which results in vasodilation and increased peripheral blood flow, leading to heat dissipation. It does not possess significant anti-inflammatory or antiplatelet effects at therapeutic doses.
Pharmacokinetics
Absorption:
Bioavailability:
60-90%
Tmax:
0.5-2 hours (oral)
FoodEffect:
Food may delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
0.95 L/kg
ProteinBinding:
10-25% (at therapeutic concentrations)
CnssPenetration:
Yes (readily crosses blood-brain barrier)
Elimination:
HalfLife:
1.25-3 hours (adults); 2-5 hours (neonates)
Clearance:
Not available (primarily metabolic clearance)
ExcretionRoute:
Renal (90-100% excreted in urine as glucuronide and sulfate conjugates, and a small amount of unchanged drug)
Unchanged:
Less than 5%
Pharmacodynamics
OnsetOfAction:
30-60 minutes
PeakEffect:
1-2 hours
DurationOfAction:
4-6 hours
Safety & Warnings
BLACK BOX WARNING
Risk of severe liver damage: Acetaminophen can cause severe liver damage if you take more than 4,000 mg in 24 hours. Risk of severe allergic reactions: Acetaminophen may cause severe skin reactions such as Stevens-Johnson Syndrome (SJS), Toxic Epidermal Necrolysis (TEN), and Acute Generalized Exanthematous Pustulosis (AGEP), which can be fatal. Stop use and seek medical help right away if you have a skin rash or other allergic reaction.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while 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
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Difficulty urinating or changes in urine output
Severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis), characterized by:
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Red or irritated eyes
+ Sores in the mouth, throat, nose, or eyes
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or persist, contact your doctor:
Upset stomach or vomiting
Trouble sleeping
Headache
Constipation
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while 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
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Difficulty urinating or changes in urine output
Severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis), characterized by:
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Red or irritated eyes
+ Sores in the mouth, throat, nose, or eyes
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or persist, contact your doctor:
Upset stomach or vomiting
Trouble sleeping
Headache
Constipation
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Yellowing of skin or eyes (jaundice)
- Dark urine
- Clay-colored stools
- Persistent nausea or vomiting
- Upper right abdominal pain
- Unusual tiredness or weakness
- Skin rash, blistering, or peeling
- Swelling of the face, lips, tongue, or throat
- Difficulty breathing or swallowing
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 symptoms you experienced.
If you have liver disease.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication in conjunction with your other medications and health issues.
Remember, do not start, stop, or adjust the dosage of any medication without first consulting 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 symptoms you experienced.
If you have liver disease.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication in conjunction with your other medications and health issues.
Remember, do not start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
To avoid potential liver problems, do not take other products that contain acetaminophen. Carefully check the labels of all medications and supplements to ensure you are not exceeding the recommended daily dose of acetaminophen.
Follow the dosage instructions precisely, and do not exceed the maximum daily dose of acetaminophen as directed. The recommended daily dose of acetaminophen can vary, but it should not exceed 4,000 mg (milligrams) per day unless specified by your doctor. However, certain individuals, such as those with liver problems or children, may require lower doses. If you are unsure about the safe amount of acetaminophen for you to take in a day, consult your doctor or pharmacist. If you suspect you have taken too much acetaminophen in a day, contact your doctor immediately, even if you are not experiencing any symptoms.
Before consuming alcohol, discuss the potential risks with your doctor.
Additionally, this medication may interfere with certain laboratory tests. Be sure to inform all your healthcare providers and laboratory personnel that you are taking this medication.
When administering this medication to children, note that different brands may have varying dosage recommendations. Consult your doctor before giving this medication to a child to ensure the correct dose is used.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor. You and your doctor will need to discuss the potential benefits and risks of taking this medication to ensure the best outcome for you and your baby.
To avoid potential liver problems, do not take other products that contain acetaminophen. Carefully check the labels of all medications and supplements to ensure you are not exceeding the recommended daily dose of acetaminophen.
Follow the dosage instructions precisely, and do not exceed the maximum daily dose of acetaminophen as directed. The recommended daily dose of acetaminophen can vary, but it should not exceed 4,000 mg (milligrams) per day unless specified by your doctor. However, certain individuals, such as those with liver problems or children, may require lower doses. If you are unsure about the safe amount of acetaminophen for you to take in a day, consult your doctor or pharmacist. If you suspect you have taken too much acetaminophen in a day, contact your doctor immediately, even if you are not experiencing any symptoms.
Before consuming alcohol, discuss the potential risks with your doctor.
Additionally, this medication may interfere with certain laboratory tests. Be sure to inform all your healthcare providers and laboratory personnel that you are taking this medication.
When administering this medication to children, note that different brands may have varying dosage recommendations. Consult your doctor before giving this medication to a child to ensure the correct dose is used.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor. You and your doctor will need to discuss the potential benefits and risks of taking this medication to ensure the best outcome for you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Abdominal pain (especially upper right quadrant)
- Loss of appetite
- Sweating
- Extreme tiredness
- Confusion
- Jaundice (yellowing of skin or eyes)
- Dark urine
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Overdose can lead to severe, irreversible liver damage or death if not treated promptly. N-acetylcysteine (NAC) is the antidote.
Drug Interactions
Major Interactions
- Alcohol (chronic heavy use increases risk of hepatotoxicity)
- Warfarin (may increase INR and bleeding risk, especially with chronic high doses of acetaminophen)
- Other hepatotoxic drugs (e.g., isoniazid, phenobarbital, phenytoin, carbamazepine, rifampin - increased risk of liver injury)
Moderate Interactions
- Cholestyramine (reduces acetaminophen absorption if given concurrently)
- Lamotrigine (acetaminophen may reduce lamotrigine levels)
- Zidovudine (acetaminophen may increase zidovudine levels and toxicity)
Minor Interactions
- Oral contraceptives (may increase acetaminophen clearance)
Monitoring
Routine Monitoring
Liver function tests (ALT, AST, bilirubin)
Frequency: Not routinely recommended for short-term or intermittent use in healthy individuals. Consider for chronic high-dose use, pre-existing liver disease, or concurrent use of hepatotoxic drugs.
Target: Within normal limits
Action Threshold: Significant elevation (e.g., >3x ULN) warrants dose reduction or discontinuation and investigation.
Symptom Monitoring
- Signs of liver damage (e.g., yellowing of skin/eyes, dark urine, persistent nausea/vomiting, abdominal pain, unusual tiredness)
- Signs of allergic reaction (e.g., rash, itching, swelling, severe dizziness, trouble breathing)
- Signs of gastrointestinal bleeding (rare, but possible with chronic high doses)
- Effectiveness of pain/fever control
Special Patient Groups
Pregnancy
Acetaminophen is generally considered the analgesic and antipyretic of choice during pregnancy when medically indicated. Studies have not shown a consistent association with major birth defects. However, use the lowest effective dose for the shortest duration possible.
Trimester-Specific Risks:
First Trimester:
Generally considered low risk.
Second Trimester:
Generally considered low risk.
Third Trimester:
Generally considered low risk. Some studies have suggested a possible link to neurodevelopmental disorders or asthma in offspring with prolonged or high-dose exposure, but evidence is inconclusive and confounding factors are present. Benefits of use should outweigh potential risks.
Lactation
Acetaminophen is considered compatible with breastfeeding. It is excreted into breast milk in small amounts, but adverse effects on breastfed infants are not expected when used at recommended doses.
Infant Risk:
Low risk (L1 - Safest)
Pediatric Use
Dosing is weight-based (10-15 mg/kg/dose). It is crucial to use appropriate formulations (e.g., liquid for infants/young children) and measuring devices to ensure accurate dosing and prevent overdose. Do not exceed 5 doses in 24 hours. Always check product concentration.
Geriatric Use
No specific dose adjustment is typically needed based on age alone. However, elderly patients may have reduced renal or hepatic function, or be on multiple medications, increasing the risk of adverse effects or interactions. Use with caution and monitor for signs of toxicity.
Clinical Information
Clinical Pearls
- Acetaminophen is not an NSAID and does not have significant anti-inflammatory effects or risk of GI bleeding/cardiovascular events associated with NSAIDs.
- The most critical safety concern is hepatotoxicity due to overdose. Patients must be educated on the maximum daily dose and to check all other medications for acetaminophen content.
- N-acetylcysteine (NAC) is the antidote for acetaminophen overdose and is most effective when administered within 8 hours of ingestion.
- Patients with chronic alcohol use, malnutrition, or pre-existing liver disease are at higher risk for hepatotoxicity even at therapeutic doses.
- While generally safe in pregnancy and lactation, always use the lowest effective dose for the shortest duration.
Alternative Therapies
- Nonsteroidal Anti-inflammatory Drugs (NSAIDs) like ibuprofen, naproxen (for pain and fever, with anti-inflammatory action)
- Aspirin (for pain, fever, and anti-inflammatory action, but with different safety profile)
- Opioid analgesics (for more severe pain, with higher risk of side effects and dependence)
- Topical analgesics (e.g., lidocaine patches, capsaicin cream)
- Non-pharmacological pain management (e.g., heat/cold therapy, physical therapy, massage)
Cost & Coverage
Average Cost:
$5 - $20 per 100 tablets (generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is 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 it's a good idea to check with your pharmacist. If you have any questions or concerns about this medication, don't hesitate to discuss them with 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 detailed information about the overdose, including the medication taken, the amount, and the time it occurred.