Phenergan 50mg 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
C
FDA Approved
Sep 1951
DEA Schedule
Not Controlled
Overview
What is this medicine?
Promethazine is an antihistamine that can help relieve allergy symptoms like sneezing and runny nose. It's also used to prevent and treat nausea and vomiting, and to help you relax or sleep before or after surgery. 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
Keep your medication at room temperature, away from light and moisture. Avoid storing it in a bathroom. Ensure that all medications are kept in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or inquire about drug take-back programs 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 scheduled dose, skip the missed dose and continue with your regular dosing 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 directed by your doctor.
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
Keep your medication at room temperature, away from light and moisture. Avoid storing it in a bathroom. Ensure that all medications are kept in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or inquire about drug take-back programs 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 scheduled dose, skip the missed dose and continue with your regular dosing 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 directed by your doctor.
Lifestyle & Tips
- Avoid alcohol and other medications that cause drowsiness, as this can worsen sedation and respiratory depression.
- Do not drive or operate heavy machinery until you know how this medication affects you, as it can cause significant drowsiness and dizziness.
- Avoid prolonged exposure to sunlight or tanning beds, as promethazine can increase sensitivity to the sun (photosensitivity).
- Drink plenty of fluids and eat fiber-rich foods to help prevent constipation, a common side effect.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
For severe nausea/vomiting: 25 mg to 50 mg orally every 4 to 6 hours as needed. For sedation/pre-operative: 25 mg to 50 mg orally at bedtime or 1 hour before surgery.
Dose Range:
25 - 50 mg
Condition-Specific Dosing:
nausea_vomiting:
25-50 mg every 4-6 hours as needed
sedation_pre_op:
25-50 mg at bedtime or 1 hour before procedure
allergy:
12.5-25 mg at bedtime or 3-4 times daily
Pediatric Dosing
Neonatal:
Contraindicated in children younger than 2 years of age due to risk of fatal respiratory depression.
Infant:
Contraindicated in children younger than 2 years of age due to risk of fatal respiratory depression.
Child:
For children âĨ 2 years: 0.5 mg/kg to 1.1 mg/kg orally as a single dose, or 12.5 mg to 25 mg orally 3 to 4 times daily (max 50 mg/day for allergy, 100 mg/day for nausea/vomiting).
Adolescent:
Same as adult dosing, with caution.
Dose Adjustments
Renal Impairment:
Mild:
No specific dose adjustment provided, use with caution.
Moderate:
No specific dose adjustment provided, use with caution. Monitor for increased sedation.
Severe:
No specific dose adjustment provided, use with caution. Monitor for increased sedation and adverse effects. Consider dose reduction.
Dialysis:
Not significantly dialyzable. Use with caution, monitor for adverse effects.
Hepatic Impairment:
Mild:
Use with caution, monitor for increased sedation.
Moderate:
Consider dose reduction. Monitor closely for increased sedation and adverse effects.
Severe:
Consider significant dose reduction or avoidance. Monitor closely for increased sedation and adverse effects.
Pharmacology
Mechanism of Action
Promethazine is a phenothiazine derivative that acts as a potent H1-receptor antagonist, blocking histamine's effects. It also possesses significant anticholinergic (muscarinic receptor blockade), antidopaminergic (D2 receptor blockade), and alpha-adrenergic blocking properties. These combined actions contribute to its antihistaminic, antiemetic, sedative, and anticholinergic effects.
Pharmacokinetics
Absorption:
Bioavailability:
25-50% (due to significant first-pass metabolism)
Tmax:
2-3 hours
FoodEffect:
Food may delay absorption but does not significantly affect bioavailability.
Distribution:
Vd:
171 L (large volume of distribution)
ProteinBinding:
93%
CnssPenetration:
Yes
Elimination:
HalfLife:
10-14 hours (variable, up to 19 hours)
Clearance:
Not available
ExcretionRoute:
Renal (primarily as metabolites), small amount in feces
Unchanged:
<1% (renal)
Pharmacodynamics
OnsetOfAction:
20 minutes (oral)
PeakEffect:
2-3 hours
DurationOfAction:
4-6 hours (antihistaminic/antiemetic), up to 12 hours (sedative)
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.
Side Effects
Important Side Effects to Report to Your Doctor Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you experience any of the following symptoms, seek medical attention right away:
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 altered mental status
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 difficult breathing
Low white blood cell counts, which can increase the risk of infection. If you experience:
+ Fever
+ Chills
+ Sore throat
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If you experience any of the following side effects, or if they bother you or do not go away, contact your doctor:
Dizziness
Drowsiness
Fatigue
Weakness
Blurred vision
Dry mouth
Upset stomach or vomiting
Trouble sleeping
* Stuffy nose
Reporting Side Effects
This is not an exhaustive list of possible side effects. 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 experience any of the following symptoms, seek medical attention right away:
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 altered mental status
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 difficult breathing
Low white blood cell counts, which can increase the risk of infection. If you experience:
+ Fever
+ Chills
+ Sore throat
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If you experience any of the following side effects, or if they bother you or do not go away, contact your doctor:
Dizziness
Drowsiness
Fatigue
Weakness
Blurred vision
Dry mouth
Upset stomach or vomiting
Trouble sleeping
* Stuffy nose
Reporting Side Effects
This is not an exhaustive list of possible side effects. 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
- Irregular or fast heartbeat
- Muscle stiffness, tremors, or uncontrolled movements
- High fever, sweating, confusion (signs of Neuroleptic Malignant Syndrome, rare)
- Yellowing of skin or eyes (jaundice)
- Unusual bleeding or bruising
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 any respiratory conditions, including:
+ Asthma
+ Chronic obstructive pulmonary disease (COPD)
+ Sleep apnea (breathing difficulties during sleep)
* If you have a history of:
+ Liver problems
+ Reye's syndrome
This list is not exhaustive, and it is crucial to discuss all your medications (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 with your existing treatments and health status. Never 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 any respiratory conditions, including:
+ Asthma
+ Chronic obstructive pulmonary disease (COPD)
+ Sleep apnea (breathing difficulties during sleep)
* If you have a history of:
+ Liver problems
+ Reye's syndrome
This list is not exhaustive, and it is crucial to discuss all your medications (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 with your existing treatments and health status. Never 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.
Before operating a vehicle or engaging in any activity that requires alertness and clear vision, wait until you understand how this medication affects you.
This medication may interfere with the accuracy of certain pregnancy tests. If you are undergoing pregnancy testing, consult with your doctor.
If you have diabetes, it is crucial to closely monitor your blood sugar levels while taking this medication.
Prior to consuming alcohol, using marijuana or other cannabis products, or taking prescription or over-the-counter medications that may cause drowsiness, discuss the potential risks with your doctor.
You may be more susceptible to sunburn while taking this medication. To minimize this risk, avoid exposure to direct sunlight, sunlamps, and tanning beds. Use protective measures such as sunscreen, clothing, and eyewear that provide adequate protection against the sun.
This medication may increase the risk of seizures, particularly in individuals with a history of seizure disorders. Consult with your doctor to determine if you are at a higher risk of experiencing seizures while taking this medication.
If you are 65 years or older, exercise caution when taking this medication, as you may be more prone to experiencing side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor. It is necessary to discuss the potential benefits and risks of this medication to both you and your baby.
Before operating a vehicle or engaging in any activity that requires alertness and clear vision, wait until you understand how this medication affects you.
This medication may interfere with the accuracy of certain pregnancy tests. If you are undergoing pregnancy testing, consult with your doctor.
If you have diabetes, it is crucial to closely monitor your blood sugar levels while taking this medication.
Prior to consuming alcohol, using marijuana or other cannabis products, or taking prescription or over-the-counter medications that may cause drowsiness, discuss the potential risks with your doctor.
You may be more susceptible to sunburn while taking this medication. To minimize this risk, avoid exposure to direct sunlight, sunlamps, and tanning beds. Use protective measures such as sunscreen, clothing, and eyewear that provide adequate protection against the sun.
This medication may increase the risk of seizures, particularly in individuals with a history of seizure disorders. Consult with your doctor to determine if you are at a higher risk of experiencing seizures while taking this medication.
If you are 65 years or older, exercise caution when taking this medication, as you may be more prone to experiencing side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, 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 drowsiness or coma
- Respiratory depression (slow, shallow breathing)
- Tachycardia (fast heart rate)
- Hypotension (low blood pressure)
- Seizures
- Dilated pupils
- Dry mouth, flushed skin
- Agitation, hallucinations (especially in children)
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive and symptomatic, including maintaining airway, breathing, and circulation.
Drug Interactions
Contraindicated Interactions
- MAO inhibitors (concurrent use or within 14 days of MAOI therapy)
Major Interactions
- CNS depressants (e.g., alcohol, opioids, benzodiazepines, barbiturates, tricyclic antidepressants): Increased sedation, respiratory depression, hypotension.
- Anticholinergics (e.g., atropine, scopolamine, tricyclic antidepressants): Increased anticholinergic effects (dry mouth, blurred vision, urinary retention, constipation).
- QT-prolonging drugs (e.g., antiarrhythmics, certain antipsychotics, macrolide antibiotics): Increased risk of QT prolongation and arrhythmias.
- Dopamine agonists (e.g., bromocriptine, cabergoline): Promethazine's antidopaminergic effects may antagonize their therapeutic effects.
Moderate Interactions
- Antihypertensives: May cause additive hypotensive effects.
- Epinephrine: Promethazine may reverse the pressor effect of epinephrine, leading to further blood pressure decrease.
- Metoclopramide: Increased risk of extrapyramidal symptoms.
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Vital Signs (BP, HR, RR)
Rationale: To establish baseline and monitor for hypotension, bradycardia, or respiratory depression.
Timing: Prior to initiation
Mental Status/Level of Consciousness
Rationale: To assess baseline sedation and monitor for excessive CNS depression.
Timing: Prior to initiation
Routine Monitoring
Level of Sedation/Alertness
Frequency: Regularly, especially during initial therapy or dose changes
Target: Desired level of sedation without excessive drowsiness or unresponsiveness
Action Threshold: Excessive somnolence, difficulty arousing, or signs of respiratory depression
Respiratory Rate and Depth
Frequency: Regularly, especially in pediatric patients or those with respiratory compromise
Target: Normal for age
Action Threshold: Bradypnea, shallow breathing, or signs of respiratory distress
Anticholinergic Effects
Frequency: Periodically
Target: Absence or mildness of symptoms
Action Threshold: Severe dry mouth, blurred vision, urinary retention, constipation
Symptom Monitoring
- Excessive drowsiness
- Dizziness
- Blurred vision
- Dry mouth
- Urinary retention
- Constipation
- Difficulty breathing
- Confusion
- Disorientation
- Involuntary movements (rare, e.g., dystonia, akathisia)
Special Patient Groups
Pregnancy
Category C. Should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Limited human data, but animal studies show some adverse effects. Avoid use in late pregnancy due to potential for respiratory depression and extrapyramidal symptoms in the neonate.
Trimester-Specific Risks:
First Trimester:
Limited data, generally avoided unless clearly needed.
Second Trimester:
Generally considered safer than first or third trimester if absolutely necessary.
Third Trimester:
Potential for respiratory depression, hypotonia, and extrapyramidal symptoms in the neonate if used close to delivery.
Lactation
Excreted into breast milk. Use with caution. Potential for sedation, irritability, or paradoxical excitation in the infant. Monitor infant for drowsiness, poor feeding, or respiratory depression.
Infant Risk:
Moderate risk (L3). Consider alternative if possible, especially in preterm or jaundiced infants.
Pediatric Use
Contraindicated in children younger than 2 years of age due to the risk of fatal respiratory depression. Use with extreme caution in children 2 years of age and older, and only when clearly indicated. Lower doses are generally required. Risk of paradoxical excitation (restlessness, agitation) in some children.
Geriatric Use
Increased susceptibility to anticholinergic effects (e.g., dry mouth, blurred vision, urinary retention, constipation), sedation, and orthostatic hypotension. Start with lower doses and titrate slowly. Monitor closely for adverse effects and cognitive impairment.
Clinical Information
Clinical Pearls
- Promethazine is a potent sedative; warn patients about impaired ability to drive or operate machinery.
- Due to its anticholinergic properties, it should be used with caution in patients with narrow-angle glaucoma, prostatic hypertrophy, or bladder neck obstruction.
- Photosensitivity can occur; advise patients to use sun protection.
- Rarely, promethazine can cause extrapyramidal symptoms (e.g., dystonia, akathisia) or Neuroleptic Malignant Syndrome (NMS).
- Avoid subcutaneous or intra-arterial administration due to severe tissue injury risk (though this applies primarily to injectable forms, it highlights the drug's irritant nature).
Alternative Therapies
- For Nausea/Vomiting: Ondansetron, Metoclopramide, Dimenhydrinate
- For Allergy: Diphenhydramine, Loratadine, Cetirizine, Fexofenadine
- For Sedation: Diphenhydramine, Hydroxyzine, Benzodiazepines (e.g., lorazepam, midazolam)
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (generic 25mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic)
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.