Phenergan 25mg Tablets
WARNING: Children:Do not give this drug to a child younger than 2 years of age. It may cause very bad and sometimes deadly breathing problems.Use with care in children 2 years of age and older. Talk with the doctor.Before your child takes this drug, tell the doctor if your child is taking any drugs that can cause breathing problems. There are many drugs that can do this. Ask the doctor or pharmacist if you are not sure. @ COMMON USES: It is used to ease allergy signs.It is used to help motion sickness.It is used to manage pain.It is used to prevent upset stomach and throwing up from surgery.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antihistamine, Antiemetic, Sedative
Pharmacologic Class
Phenothiazine derivative, H1-receptor antagonist
Pregnancy Category
Category C
FDA Approved
Mar 1951
DEA Schedule
Not Controlled
Overview
What is this medicine?
Promethazine is a medication that can help with nausea, vomiting, allergies, and motion sickness. It also causes drowsiness, so it's often used to help with sleep or to calm you down before a procedure. It works by blocking certain natural substances in your body that cause these symptoms.
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. If it causes stomach upset, take it with food to help minimize this side effect. If you're using this medication to prevent motion sickness, take it 30 to 60 minutes before traveling.
Storing and Disposing of Your Medication
Store your medication at room temperature, away from light and moisture. Keep it in a dry place, such as a closet or drawer, and avoid storing it in the bathroom. Keep all medications out of the reach of children and pets to ensure their safety. When you're finished with your medication or it expires, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Check with your pharmacist for guidance on the best way to dispose of your medication, and consider participating in a drug take-back program in your area.
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 regular schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, follow your doctor's instructions and do not take it more frequently than recommended.
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. If it causes stomach upset, take it with food to help minimize this side effect. If you're using this medication to prevent motion sickness, take it 30 to 60 minutes before traveling.
Storing and Disposing of Your Medication
Store your medication at room temperature, away from light and moisture. Keep it in a dry place, such as a closet or drawer, and avoid storing it in the bathroom. Keep all medications out of the reach of children and pets to ensure their safety. When you're finished with your medication or it expires, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Check with your pharmacist for guidance on the best way to dispose of your medication, and consider participating in a drug take-back program in your area.
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 regular schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, follow your doctor's instructions and do not take it more frequently than recommended.
Lifestyle & Tips
- Avoid driving or operating heavy machinery until you know how this medication affects you, as it can cause significant drowsiness and dizziness.
- Avoid alcohol and other medications that cause drowsiness (e.g., pain relievers, sleeping pills, anxiety medications) as they can increase the sedative effects of promethazine.
- Avoid prolonged sun exposure and use sunscreen, as promethazine can increase sensitivity to sunlight.
- To relieve dry mouth, suck on sugarless candy or ice chips, or use a saliva substitute.
- Stay hydrated to help with potential constipation.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
25 mg orally every 4 to 6 hours as needed
Dose Range:
12.5 - 50 mg
Condition-Specific Dosing:
nauseaAndVomiting:
25 mg orally every 4 to 6 hours as needed; initial dose 25 mg, then 12.5-25 mg every 4-6 hours as needed
allergicConditions:
25 mg orally at bedtime; or 12.5 mg orally before meals and at bedtime
sedation:
25-50 mg orally at bedtime
motionSickness:
25 mg orally 30-60 minutes before travel, then 25 mg 8-12 hours later if needed
Pediatric Dosing
Neonatal:
Not established (Contraindicated in children younger than 2 years of age)
Infant:
Not established (Contraindicated in children younger than 2 years of age)
Child:
For children âĨ 2 years: 0.5 mg/kg orally every 4 to 6 hours as needed; maximum 25 mg/dose or 100 mg/day. For motion sickness: 0.5 mg/kg 30-60 minutes before travel, then 0.5 mg/kg 8-12 hours later if needed.
Adolescent:
Same as adult dosing, generally 12.5-25 mg orally every 4 to 6 hours as needed.
Dose Adjustments
Renal Impairment:
Mild:
No specific dose adjustment recommended, use with caution.
Moderate:
No specific dose adjustment recommended, use with caution.
Severe:
Use with caution; consider lower doses and extended intervals due to potential for accumulation of metabolites. Monitor for increased side effects.
Dialysis:
Not significantly dialyzable. Use with caution; monitor for increased side effects.
Hepatic Impairment:
Mild:
No specific dose adjustment recommended, use with caution.
Moderate:
Use with caution; consider lower doses and extended intervals due to extensive hepatic metabolism. Monitor for increased side effects.
Severe:
Use with caution; consider lower doses and extended intervals due to extensive hepatic metabolism. Monitor for increased side effects.
Pharmacology
Mechanism of Action
Promethazine is a phenothiazine derivative that acts as a potent, competitive antagonist of histamine H1 receptors. Its antiemetic effects are thought to be due to its anticholinergic and central nervous system (CNS) depressant properties, including antagonism of dopamine D2 receptors in the chemoreceptor trigger zone (CTZ). It also possesses significant anticholinergic, sedative, and alpha-adrenergic blocking effects.
Pharmacokinetics
Absorption:
Bioavailability:
Variable, approximately 25% (due to extensive first-pass metabolism)
Tmax:
2-3 hours
FoodEffect:
Food may delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
171 L (large volume of distribution, indicating extensive tissue distribution)
ProteinBinding:
Approximately 93%
CnssPenetration:
Yes (readily crosses the blood-brain barrier)
Elimination:
HalfLife:
10-14 hours (range 7-19 hours)
Clearance:
Not readily available, but primarily hepatic metabolism followed by renal excretion.
ExcretionRoute:
Renal (primarily as inactive metabolites), small amount in feces.
Unchanged:
<1% (renal)
Pharmacodynamics
OnsetOfAction:
20 minutes (oral)
PeakEffect:
Not precisely defined, generally within 2-3 hours post-dose.
DurationOfAction:
4-6 hours (antihistaminic/antiemetic); 6-12 hours (sedative effects)
Safety & Warnings
BLACK BOX WARNING
RESPIRATORY DEPRESSION: Promethazine should not be used in pediatric patients less than 2 years of age because of the potential for fatal respiratory depression. Postmarketing cases of respiratory depression, including fatalities, have been reported with use of promethazine in pediatric patients less than 2 years of age. Caution should be exercised when administering promethazine to pediatric patients 2 years of age and older. A lower dose of promethazine should be used in pediatric patients 2 years of age and older and concomitant administration of other drugs with respiratory depressant effects should be avoided.
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 high or low blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Abnormal heart rhythms, such as:
+ Fast or slow heartbeat
Neurological symptoms, including:
+ Trouble controlling body movements
+ Twitching
+ Changes in balance
+ Difficulty swallowing or speaking
+ Shakiness
+ Trouble moving around
+ Stiffness
Confusion or disorientation
Feeling nervous or excitable
Hallucinations (seeing or hearing things that are not there)
Mood changes
Ringing in the ears
Seizures
Unexplained bruising or bleeding
Yellowing of the skin or eyes
Changes in eyesight
Neuroleptic malignant syndrome (NMS), a potentially life-threatening condition, characterized by:
+ Fever
+ Muscle cramps or stiffness
+ Dizziness
+ Severe headache
+ Confusion
+ Changes in thinking
+ Fast heartbeat
+ Abnormal heartbeat
+ Excessive sweating
Severe breathing problems, including:
+ Slow, shallow, or troubled breathing
Low white blood cell counts, which may increase the risk of infection, characterized by:
+ Fever
+ Chills
+ Sore throat
Other Possible Side Effects
Most people experience few or no side effects while taking this medication. However, if you notice any of the following symptoms, contact your doctor or seek medical attention if they bother you or persist:
Dizziness
Drowsiness
Fatigue
Weakness
Blurred vision
Dry mouth
Upset stomach or vomiting
Trouble sleeping
* Stuffy nose
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, contact 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 high or low blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Abnormal heart rhythms, such as:
+ Fast or slow heartbeat
Neurological symptoms, including:
+ Trouble controlling body movements
+ Twitching
+ Changes in balance
+ Difficulty swallowing or speaking
+ Shakiness
+ Trouble moving around
+ Stiffness
Confusion or disorientation
Feeling nervous or excitable
Hallucinations (seeing or hearing things that are not there)
Mood changes
Ringing in the ears
Seizures
Unexplained bruising or bleeding
Yellowing of the skin or eyes
Changes in eyesight
Neuroleptic malignant syndrome (NMS), a potentially life-threatening condition, characterized by:
+ Fever
+ Muscle cramps or stiffness
+ Dizziness
+ Severe headache
+ Confusion
+ Changes in thinking
+ Fast heartbeat
+ Abnormal heartbeat
+ Excessive sweating
Severe breathing problems, including:
+ Slow, shallow, or troubled breathing
Low white blood cell counts, which may increase the risk of infection, characterized by:
+ Fever
+ Chills
+ Sore throat
Other Possible Side Effects
Most people experience few or no side effects while taking this medication. However, if you notice any of the following symptoms, contact your doctor or seek medical attention if they bother you or persist:
Dizziness
Drowsiness
Fatigue
Weakness
Blurred vision
Dry mouth
Upset stomach or vomiting
Trouble sleeping
* Stuffy nose
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, contact 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:
- Severe drowsiness or difficulty waking up
- Slow or shallow breathing
- Confusion, disorientation, or hallucinations
- Unusual muscle movements or stiffness (e.g., tremors, difficulty speaking, rigid muscles)
- Yellowing of the skin or eyes (jaundice)
- Dark urine or pale stools
- Severe dizziness or fainting
- Difficulty urinating
- Vision changes or eye pain
- Unusual bleeding or bruising
- Signs of an allergic reaction (rash, itching, swelling, severe dizziness, trouble breathing)
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 you experienced, including any symptoms that occurred.
If you have respiratory conditions, such as asthma, chronic obstructive pulmonary disease (COPD), or sleep apnea, which involves breathing difficulties during sleep.
If you have a history of liver problems or Reye's syndrome, a rare but serious condition that can affect the liver and brain.
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
Your complete medical history, including any health problems you have or have had in the past
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
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 you experienced, including any symptoms that occurred.
If you have respiratory conditions, such as asthma, chronic obstructive pulmonary disease (COPD), or sleep apnea, which involves breathing difficulties during sleep.
If you have a history of liver problems or Reye's syndrome, a rare but serious condition that can affect the liver and brain.
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
Your complete medical history, including any health problems you have or have had in the past
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Before engaging in activities that require alertness and clear vision, such as driving, wait until you understand how this drug affects you.
Be aware that this medication may interfere with the accuracy of some pregnancy tests. If you are concerned about this, discuss it with your doctor. If you have diabetes, it is crucial to closely monitor your blood sugar levels while taking this medication.
Before consuming alcohol, using marijuana or other cannabis products, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor. This medication can increase your sensitivity to the sun, making you more prone to sunburn. To minimize this risk, avoid exposure to direct sunlight, sunlamps, and tanning beds, and use protective measures such as sunscreen, clothing, and eyewear.
There is a potential increased risk of seizures associated with this medication, particularly in individuals with a history of seizures. Discuss your individual risk with your doctor. If you are 65 years or older, exercise caution when taking this medication, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, it is essential to discuss the benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.
Be aware that this medication may interfere with the accuracy of some pregnancy tests. If you are concerned about this, discuss it with your doctor. If you have diabetes, it is crucial to closely monitor your blood sugar levels while taking this medication.
Before consuming alcohol, using marijuana or other cannabis products, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor. This medication can increase your sensitivity to the sun, making you more prone to sunburn. To minimize this risk, avoid exposure to direct sunlight, sunlamps, and tanning beds, and use protective measures such as sunscreen, clothing, and eyewear.
There is a potential increased risk of seizures associated with this medication, particularly in individuals with a history of seizures. Discuss your individual risk with your doctor. If you are 65 years or older, exercise caution when taking this medication, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, it is essential to discuss the benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.
Overdose Information
Overdose Symptoms:
- Severe drowsiness or coma
- Respiratory depression (slow, shallow breathing)
- Tachycardia (fast heart rate)
- Hypotension (low blood pressure)
- Anticholinergic effects (dilated pupils, dry mouth, flushed skin, fever, urinary retention, absent bowel sounds)
- Agitation, restlessness, hallucinations (especially in children)
- Seizures
- Extrapyramidal symptoms (involuntary muscle movements)
What to Do:
Seek immediate medical attention. Call 911 or Poison Control (1-800-222-1222). Treatment is supportive, including maintaining airway, breathing, and circulation. Naloxone may be considered if opioid co-ingestion is suspected. Physostigmine may be used for severe anticholinergic symptoms but is rarely recommended due to potential for adverse effects.
Drug Interactions
Contraindicated Interactions
- MAO inhibitors (concurrent use or within 14 days of MAOI discontinuation) - risk of prolonged and intensified anticholinergic and CNS depressant effects.
- Other phenothiazines (additive effects, increased toxicity).
Major Interactions
- CNS depressants (e.g., opioids, benzodiazepines, barbiturates, alcohol, tricyclic antidepressants, other antihistamines) - additive CNS depression, respiratory depression, profound sedation.
- Anticholinergic drugs (e.g., atropine, scopolamine, tricyclic antidepressants) - additive anticholinergic effects (dry mouth, blurred vision, urinary retention, constipation).
- QT-prolonging drugs (e.g., antiarrhythmics, certain antipsychotics, macrolide antibiotics) - theoretical risk of additive QT prolongation, though promethazine's effect on QT is generally minor at therapeutic doses.
- Dopamine agonists (e.g., bromocriptine, cabergoline) - promethazine's antidopaminergic effects may antagonize their therapeutic effects.
Moderate Interactions
- Antihypertensives - potential for additive hypotensive effects.
- Epinephrine - promethazine may reverse the pressor effect of epinephrine, leading to a further decrease in blood pressure.
- Hepatotoxic drugs - theoretical increased risk of liver injury with concurrent use.
Minor Interactions
- Not readily available for specific minor interactions, but general caution with drugs affecting liver enzymes or renal excretion.
Monitoring
Baseline Monitoring
Patient history (especially respiratory, cardiac, neurological conditions)
Rationale: To identify contraindications or risk factors for adverse effects (e.g., asthma, COPD, sleep apnea, glaucoma, prostatic hypertrophy, seizure disorder, cardiovascular disease).
Timing: Prior to initiation of therapy
Concomitant medications review
Rationale: To identify potential drug-drug interactions, especially with CNS depressants or anticholinergic agents.
Timing: Prior to initiation of therapy
Routine Monitoring
Level of consciousness/Sedation
Frequency: Regularly, especially during initial therapy and dose adjustments
Target: Alert and oriented, or appropriate level of sedation for indication
Action Threshold: Excessive drowsiness, somnolence, unresponsiveness; consider dose reduction or discontinuation.
Respiratory rate and effort
Frequency: Regularly, especially in pediatric patients and those with respiratory compromise
Target: Normal for age
Action Threshold: Bradypnea, shallow breathing, signs of respiratory distress; particularly critical in children < 2 years.
Anticholinergic effects (e.g., dry mouth, blurred vision, urinary retention, constipation)
Frequency: As needed, based on patient report
Target: Minimal to tolerable
Action Threshold: Severe or bothersome symptoms; consider dose reduction or alternative.
Blood pressure (especially in elderly or those with cardiovascular disease)
Frequency: Periodically, if concerns for orthostatic hypotension
Target: Within patient's normal range
Action Threshold: Significant orthostatic hypotension or sustained hypotension.
Symptom Monitoring
- Excessive drowsiness or sedation
- Difficulty breathing or shallow breathing
- Confusion or disorientation
- Hallucinations
- Unusual muscle movements (e.g., dystonia, akathisia)
- Dry mouth, blurred vision, difficulty urinating, constipation
- Dizziness or lightheadedness upon standing
- Skin rash or photosensitivity
Special Patient Groups
Pregnancy
Promethazine is Pregnancy Category C. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Limited human data suggest no increased risk of major birth defects, but some studies have shown an association with maternal use near term and neonatal adverse effects (e.g., irritability, tremors).
Trimester-Specific Risks:
First Trimester:
Limited data, but generally not associated with increased risk of major malformations.
Second Trimester:
Generally considered safer than first or third trimester, but still Category C.
Third Trimester:
Use near term may cause neonatal adverse effects such as irritability, tremors, or respiratory depression due to its sedative properties. Avoid use in the last two weeks of pregnancy if possible.
Lactation
Promethazine is excreted into breast milk. Due to the potential for serious adverse reactions in nursing infants (e.g., sedation, irritability, paradoxical excitation, respiratory depression), use during breastfeeding should be approached with caution. The American Academy of Pediatrics considers it a drug for which the effect on the nursing infant is unknown but may be of concern. Consider alternative agents if possible, especially in newborns or preterm infants.
Infant Risk:
L3 (Moderately safe; use with caution). Potential for sedation, irritability, paradoxical excitation, respiratory depression, especially in young infants.
Pediatric Use
Contraindicated in children younger than 2 years of age due to the potential for fatal respiratory depression. Use with extreme caution in children 2 years of age and older, and use the lowest effective dose. Avoid concomitant use with other respiratory depressants. Children are more susceptible to paradoxical excitation (restlessness, agitation) and extrapyramidal symptoms.
Geriatric Use
Elderly patients are more susceptible to the anticholinergic effects (e.g., dry mouth, blurred vision, urinary retention, constipation), sedation, confusion, and orthostatic hypotension. Use the lowest effective dose and titrate slowly. Avoid in elderly patients with dementia-related psychosis due to increased risk of mortality.
Clinical Information
Clinical Pearls
- Promethazine is a potent sedative; warn patients about impaired ability to drive or operate machinery.
- The Black Box Warning for respiratory depression in children < 2 years old is critical; never use in this age group.
- Avoid subcutaneous or intra-arterial administration due to severe tissue injury risk (though this applies more to injectable forms, it highlights the drug's irritant nature).
- Patients should be advised to avoid alcohol and other CNS depressants.
- Promethazine can interfere with immunological pregnancy tests, causing false-negative or false-positive results.
- Use with caution in patients with narrow-angle glaucoma, prostatic hypertrophy, bladder neck obstruction, pyloroduodenal obstruction, or seizure disorders due to anticholinergic effects and potential to lower seizure threshold.
- May cause photosensitivity; advise patients to use sun protection.
Alternative Therapies
- For nausea/vomiting: Ondansetron, Metoclopramide, Prochlorperazine, Dimenhydrinate
- For allergic conditions: Diphenhydramine, Loratadine, Cetirizine, Fexofenadine
- For sedation/insomnia: Diphenhydramine, Hydroxyzine, Zolpidem, Trazodone
- For motion sickness: Dimenhydrinate, Scopolamine (transdermal)
Cost & Coverage
Average Cost:
$10 - $30 per 30 tablets (25mg generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (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 emergency 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.