1 What is promethazine?

Brand: Phenergan, Phenadoz, Promethegan

Generic: Promethazine

Promethazine is an antipsychotic medication and a first-class antihistamine of the phenothiazine family.

Promethazine has a range of medical uses including:

  • Treatment of symptoms of allergies such as sneezing, skin rashes, itching, itchy or watery eyes, and hives
  • Prevention of motion sickness
  • Treatment of pain after surgery or vomiting and nausea
  • As a sleeping aid or sedative
  • Reduction of restlessness, nervousness and agitation caused by psychiatric conditions

Promethazine is not used for treatment of asthma, pneumonia symptoms or other infections of the lower respiratory tract.

Promethazine has hazardous side effects like unmanageable movements including twitching of the tongue, eyes, lips, arms, face or even legs. You should stop using promethazine and call your health practitioner if you experience any adverse side effects. Children under the age of 2 should not be administered promethazine. This is because promethazine can bring upon breathing issues or even death when given to young children. Carefully follow the doctor’s instructions when giving this medication to children.

Tell your physician of any other medical prescriptions and over-the-counter drugs you may have acquired or are still using, including: minerals, vitamins, drugs and herbal products. Also, consult your doctor before starting a new medication.

Before taking this medicine

Inform your doctor, before taking promethazine, if you are planning to have a baby or if you are already expectant.

Apprise a doctor if you have experienced any of the following:

  • A sulfite allergy
  • Respiratory disorders such as: sleep apnea, asthma or COPD (chronic obstructive pulmonary disease)
  • Glaucoma
  • Seizures in the recent past
  • A weak immune system (bone marrow depression)
  • Urination problems or enlarged prostate
  • Obstruction or stomach ulcer
  • High blood pressure or heart disease
  • Liver disease
  • Tumors in tissues of the adrenal gland
  • Low blood calcium levels (hypocalcemia)
  • A side effect that needs attention
  • An allergic reaction during the use of promethazine or other forms of phenothiazine

What to avoid while taking promethazine:

  • Avoid anything requiring alertness and being awake, like driving. Promethazine impacts your thinking ability or reactions.
  • Avoid drinking alcohol as this causes an increase in the severity of promethazine side effects.
  • Avoid breastfeeding while on promethazine as it is not yet known whether it can be passed to children through breast milk.
  • Avoid quick and drastic movements. Take your time when changing posture; for example, when standing upright from a lying or sitting position.
  • Avoid direct exposure to sunlight and indoor tanning; this is because promethazine makes you prone to sunburn more easily. Wear protective attire and use sunscreen (SPF 30 or higher) when you are outdoors.

What to do in case you skip a dose:

  • Do not take more than the prescribed dosage to cover for a missed one.
  • When you remember, take the dose that you skipped. But if the time for the subsequent dose is near, skip the missed dose completely.

What to do in case you overdose:

Symptoms associated with overdosing on this drug may include loss of coordination, weak or shallow breathing, overactive reflexes, fainting, dilated pupils, severe drowsiness or weakness, or seizure (convulsions).

If you experience any of the symptoms associated with overdosing, call the Poison Help line and seek immediate medical attention.

2 Promethazine usage

Promethazine can be used to cure several ailments including motion sickness, nausea, anxiety, sleep before and after surgery, allergies, relieving pain after undergoing surgery, sedation and restlessness.

Drugs are categorized into similar classes which function in much the same manner and work by treating very similar conditions. Promethazine is grouped under the antihistamines and antiemetic class of drugs. Histamines are released when you are exposed to allergic substances which can include pollen, chemicals or dander. Promethazine, an antihistamine, inhibits the release of histamine from certain body cells preventing some allergic responses.

This part also reduces the vomit reflex by suppressing the part of the brain which produces signals to induce vomiting.

By limiting the production of histamine, promethazine causes somnolence and also assists in preventing the sensation of pain to some extent. Histamine helps to keep you awake, alert and also heightens the senses, thus when all this is suppressed, pain is controlled effectively.

3 Promethazine dosage

Your dose, form of drug, and frequency at which the drug is administered will be determined by:

  • Age of the patient
  • Acuteness of your condition
  • Other underlying conditions you may have
  • The ailment being treated
  • Your response to the former dose

This medication can be used to treat:


Adult dose (18-64 years)

  • 25 mg is the moderate dose taken before bed, and 12.5 mg is taken after every 4 hours before meals.
  • The dose can be increased after the doctor reviews it. To treat allergies, 25 mg is the recommended dose.

Child dosage (2-17 years)

  • Before bed take 25 mg, and 12.5 mg before meals in a sequence of four hours.
  • The dose is subject to be reviewed by the doctor.
  • The usual dose is 25 mg for treating allergies.

Infant dosage (0-23 months)

  • It is unclear whether this drug is effective and safe for use in infants.

Senior dosage (age 65 and above)

  • Organs of older people, especially the heart, liver and kidneys, may not work as well as they used to, which might cause the drug to be processed at a slower rate. Consequently, the drug can stay in the body longer, making you vulnerable to develop side effects.
  • Your general practitioner will start at a lower dose with a suitable treatment plan to avoid an influx of the drug in the body.

Motion sickness

Adult (18-64 years)

  • Take 25 mg twice daily.
  • For the first dose, take it 30 minutes before travelling and the second 8 to 12 hours later, if there is a need to.
  • On subsequent days, take 25 mg immediately after you wake up, and just after the last meal of the day.

Child dosage (2-17 years)

  • The standard dose is 12.5 to 25 mg twice per day.
  • The first dose should be taken 30 minutes before travel and the second 8 to 12 hours later if required.
  • If you travel successively in the days that follow, take 12.5 to 25 mg as soon as you get up and right after the final meal of the day.

Infant dosage (0-23 months)

  • It is not yet established whether or not promethazine hydrochloride is effective and safe for children below two years old.

Senior dosage (age 65 and older)

  • Since the kidneys, liver and hearts of older people do not function like they used to, it may be required that the doctor finds the least possible dose which is effective. This will reduce the risk of developing adverse side effects.

Sleep aid and pain relieving after surgery

Adult dosage (18-64 years)

  • Following a surgery, the recommended dose is 25 to 50 mg to foster sleep and to be used with other medications that can help in pain relieving.

Child dosage (2-17 years)

  • To promote sleep and combination with other pain relieving drugs after surgery, use 12.5 to 25 mg.

Infant dosage (0-23 months)

  • Promethazine hydroxide has not yet been confirmed whether it is effective and safe to be used in infants.

Senior dosage (age 65 and above)

  • The heart, liver and kidneys of elderly people may not function as well in processing the drug. As a result, the drug may sit in your body longer, thus the doctor should find the least possible dose that is still effective.

Sleep aid and anxiety relieving before surgery

Adult dosage (18-64 years)

  • On the night before the surgery, take 12.5 to 25 mg to relieve restlessness and induce sleep.

Child dosage (2-17 years)

  • Take 12.5 to 25 mg on the night before surgery to treat anxiety and promote sleep.

Infant dosage (0-23 months)

  • It is unclear whether promethazine hydrochloride is beneficial or harmful to children below the age of two years.

Senior dosage (age 65 and above)

  • Since the body organs involved in processing this drug are not as efficient (lungs, heart and kidneys), the doctor should start with a low dose to avoid the drug from building up to toxic levels. This is a preventive measure against side effects.

Nausea and vomiting

Adult dosage (18-64 years) and child dosage (2-17 years)

  • The recommended dose may be between 12.5 to 25 mg taken after every 4 to 6 hours, if required.
  • To prevent barfing and seasickness, the prescribed dose is 25 mg taken after 4 to 6 hours.

Infant dosage (0-23 months)

  • It is unconfirmed if promethazine hydrochloride is harmful or beneficial to children who are below two years.

Senior dosage (age 65 and above)

  • The kidneys, liver and heart of older people do not work as efficiently as they used to. This causes the body to process promethazine slowly and can result in a toxic build up in the body, causing severe side effects.
  • Your general practitioner or pharmacist will prescribe you a detailed dosage based on your general state of health and severity of the condition.

4 What is promethazine used for?

Promethazine is mostly used to treat allergic reactions such as itchy or watery eyes, runny nose, hives, sneezing, itchy skin rashes, and general itchiness. It also heals motion sickness, pain after surgery, nausea and vomiting, and may be coupled as a sedative or sleeping aid.

Additional uses of promethazine are to treat some symptoms of inferior respiratory tract infections, asthma, and pneumonia.

5 Promethazine side effects

Most reported secondary effects caused by the use of promethazine include:

  • Dizziness and drowsiness
  • A mouth that is dry
  • Indistinct and hazy vision
  • Congested nose
  • Ringing in the ears
  • Costiveness and constipation
  • Gaining weight
  • Impotence and trouble attaining an orgasm

These side effects are mild and disappear within a few days. If they are hazardous and persistent, seek your doctor's or pharmacist’s help.

There are also more serious secondary effects of promethazine use. If you detect any of the following, discontinue your dosage and consult your medic as soon as possible:

  • Restlessness or feeling frazzled and tense
  • Jerking of muscles especially those of the eyes, legs, arms, tongue or lips
  • Uncontrolled quivering
  • Driveling or problems associated with swallowing
  • Staggering and problems finding your balance
  • Feeling like you may faint or lose consciousness
  • Seizures and fits
  • Photophobia and problems with eye sight
  • Pallor
  • Easily bruising and bleeding uncontrollably
  • Malaise or common cold
  • Symptoms of flu
  • Perception of things which do not exist
  • Illness or discomfort of the digestive system and abdominal pain
  • Rashes on the skin
  • Jaundice; yellow color of the skin, eyes and urine
  • Swelling and pain in joints
  • Swollen glands

There can be other serious symptoms which will require medical attention such as:

  • Slow heart beat rate
  • Pain in the muscles and rigidity
  • Pain in the chest
  • Vomiting
  • Unusual behavior and thoughts
  • Paleness of the skin
  • Fainting
  • Bradypnea

If you note any allergic reactions including; breathing complications, itching, edema of the face, lips, mouth or tongue, and hives, get emergency help.


6 Availability of promethazine

In some countries, promethazine is available over the counter, but in the US it is a prescription drug.

Promethazine is a category of drugs referred to as phenothiazines, which work by modifying the actions of chemicals that are found in the human brain. Promethazine also functions as an antihistamine and works against the action of histamine in the human body.

7 Promethazine DM

Dextromethorphan plus promethazine is an amalgamation of drugs which make up promethazine DM. This drug treats allergies, sneezing due to flu, coughing, hay fever, some diseases and a runny nose.

Promethazine, a phenothiazine, works by inhibiting the action of histamines, which lead to the development of allergic reactions. Dextromethorphan subdues a cough by causing the brain to reduce the inclination to cough.

Promethazine was approved as medicine in 1957 by the FDA (Food and Drug Administration) and is made by Qualitest Pharmaceuticals.

Promethazine DM cautions

Promethazine DM can be lethal and cause death and breathing complications to children hence it has a boxed warning, which contains information on use safeguarding the patient.

Refer with your health expert before giving this drug to children above the age of two, but never give it to children below that age. Before giving this drug to your child, inform the doctor of any lung diseases or disorders. Also, if the child is taking any sort of medication, tell the doctor.

Seek medical attention immediately if you notice any of these symptoms in your child:

  • Straining to breath
  • Whistling or wheezing sounds when respiring
  • Laborious breathing
  • Ceasing, or a reduced rate, of  breath

After taking promethazine DM, a child may become nervous and restless. Consult with your general practitioner if symptoms persist, because persisting symptoms increase danger to the child. Also exercise caution when administering this drug to a family with a history of sudden infant death syndrome (SIDS).

In older people, side effects may include dizziness and confusion, which may make them fall rather easily. Side effects in older people tend to be acute since they have intensified sensitivity to the drug.

Generally, promethazine DM is not required to treat persistent coughs due to smoking or chronic breathing complications. Bring these issues to the doctor to find appropriate treatment.

Before being prescribed promethazine DM, tell your doctor if you ever had:

  • Liver complications
  • Disorders of breathing
  • Heart complications
  • Bowel or stomach anomalies
  • Glaucoma
  • Seizures or fits
  • Blood and immune system disorders
  • Enlargement of the prostate or urinating difficulty
  • Diabetes

Inform your medical practitioner if you are being medicated with this drug before you undergo any serious medical procedure or surgery. Take promethazine DM with plenty of water to loosen mucus in the lungs.

If you do not see positive results and your cough still persists, report to your doctor immediately.

8 Promethazine syrup

Promethazine syrup, an anti-histamine, works by inhibiting secretion of histamine to decrease allergic symptoms, nausea, hives and vomiting.

This syrup is effective in alleviating allergy symptoms. It can also be used to control nausea and queasiness during and after surgery. This syrup can be used as a sedative, treating conditions like motion sickness or pain associated with surgery. Promethazine syrup can be used alongside other drugs in off the label treatment after the doctor reviews your condition fully.

You should abstain from using this drug if:

  • You are allergic to the ingredients constituting promethazine syrup
  • You have a central nervous system condition, depression or coma
  • You are medicated with astemizole, terfenadine, tramadol, or cisapride

Before using promethazine syrup:

Tell your doctor of all medical conditions that you have which may interfere with the healing mechanism of promethazine syrup; these may include:

  • Pregnancy, breastfeeding, or if you intend to become pregnant
  • If you take any prescribed or non-prescribed medicine, dietary supplements, or herbal concoctions
  • Have an allergy to some food, drugs and other substances
  • Have a history of nervous system suppression, heart complications, glaucoma, increased eye pressure, low blood pressure, bone marrow depression, liver conditions, stomach problems, seizures, Reye syndrome, Parkinson’s disease, blocked bowels or bladder, or an enlarged prostate
  • If you drink alcohol regularly and in large amounts

How to use promethazine syrup:

Check the instructions on and within the package for correct dosing and follow your doctor’s orders.

  • Take promethazine syrup alongside or excluding food. If you get affected by stomach upsets, take it alongside some food to relieve irritation.
  • Ensure you take an accurate dosage as prescribed.
  • Take it 30-60 minutes before travelling when curing motion sickness.
  • If you forgot a dose, take it as soon as you remember. Unless advised by a doctor, do not double the dose you missed if it is near the time for the next dose.

Ask for any clarifications if you still have uncertainties concerning your medication.

9 Promethazine with codeine

Codeine combats cough and pain since it is a narcotic. Promethazine, however, is an antihistamine. This combination of promethazine and codeine may be resourceful in treating cold, flu and some common allergic symptoms. This combination may be used in off-label treatment procedures.

Nonetheless, you should not give this drug to children below six years of age, or if you have lung conditions, pneumonia or asthma, or are allergic to codeine and promethazine. It is advisable that you do not use it if you fall under those categories. If a child has undergone surgical therapy, don’t use this medicine to treat the tonsils or adenoids.

Get emergency medical help if your child develops breathing problems, pallor, acute dizziness, or if they can’t awake from sleep.

In other people, codeine is broken down and absorbed very rapidly. Codeine flooding the body at dangerously high levels can occur, and slowed breathing, death or both can result.

For maximum safety, tell your doctor if you suffer from the following conditions:

  • Sleep apnea, asthma, COPD and other breathing disorders
  • You are epileptic or affected by seizures
  • Had a fatal head injury or tumor
  • Glaucoma
  • Stomach ulceration, ulcerative colitis, an obstructed digestive tract
  • Kidney or liver disease
  • Thyroid disorder
  • Enlarged prostate and urination disorders
  • If you recently had a surgery of the stomach or urinary tract

Effects of this drug to unborn children, whether harmful or beneficial, is unclear. However, it can cause your child to develop withdrawal symptoms after birth since babies in the womb can become addicted to the drug. They will therefore need some therapy to get them off the drug during the first few weeks.

Codeine can be passed to the baby through breast milk, causing harm to the child. Low milk production can also be an effect of using antihistamines. Never use this drug when breastfeeding, pregnant, or expecting to become pregnant.

10 Is promethazine a narcotic?

Promethazine is not a narcotic but an antihistamine. However, it is commonly prescribed to be in use with codeine in cough syrups.

11 Promethazine high

With prolonged and excessive use, promethazine becomes addictive and can get you high.

12 How long does promethazine stay in your system?

If you discontinued your dosage recently after using promethazine for a long duration, you may be affected by irritating withdrawal symptoms. Some of the secondary effects may still affect you, even after you ceased taking your medication. Such side effects are mostly associated with visual anomalies due to promethazine.

To know exactly how long promethazine lingers in your system, it is important to know how long its elimination half-life is. The moderate eradication half-life of promethazine is about 9 to 16 hours as related to when administered intramuscularly or though the vein. Using this information, it can be assumed that promethazine will stay for about 2 to 4 days after administration intramuscularly or intravenously.

If administered orally or through the rectum, the eradication half-life is between about 3 and 5 days after taking the drug. What is being said is that the drug should completely be eliminated from your system within 5 days of your ultimate dose. 

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