Promethazine For Children: Dosage And Side Effects

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Promethazine is an antihistamine drug that provides symptomatic relief from the common cold, allergies, short-term sleep issues, vomiting, and nausea due to vertigo/motion sickness.

While generally safe, Promethazine for kids must be administered with caution as it is a sedative drug and is likely to induce sleepiness (1). Some brand names under which Promethazine is available over the counter (OTC) are Phenergan, Avomin, and Sominex.

Keep reading to know more about the safety, uses, and side effects of Promethazine for kids.

What Is Promethazine?

Promethazine, a first-generation antihistamine, belongs to the phenothiazine class of drugs. It acts by reducing the actions of natural substances in the body, such as histamine, dopamine, and acetylcholine. The US Food and Drug Administration (FDA)-approved uses of Promethazine include (2) (3):

  • Allergies. Seasonal allergies (allergic rhinitis) causing runny nose and watery eyes, allergic conjunctivitis, skin conditions causing itching and swelling, and use in combination with other drugs to treat severe life-threatening allergic reactions.
  • Nausea and vomiting due to anesthesia, chemotherapy, or post-surgery effects.
  • Motion sickness. Most effective when given 30 minutes to one hour before travel or other trigger factors.
  • Sedation. Used along with painkillers to calm patients before or after surgery.

Is Promethazine Safe For Children?

The FDA contraindicates the use of Promethazine tablets or suppositories in pediatric patients below two years of age. It should be used with caution in children aged two years and above due to the risk of breathing problems (respiratory depression). Promethazine is not recommended for uncomplicated vomiting in children but only when vomiting is prolonged and due to a diagnosed condition. Children below 16 years of age should not use some products that contain Promethazine in combination with other drugs. You should consult a pediatrician before giving Promethazine to your child (2) (4).

What Is The Dosage Of Promethazine For Children?

Promethazine is available as tablets, syrups, suppositories, and injectable solutions. Seek a pediatrician’s prescription before giving this drug to children. The following table may help you understand the Promethazine dosage, with reference to Phenergan brand oral tablets, syrups, and rectal suppositories containing Promethazine HCl for pediatric patients (4).

Allergy6.25mg to 12.5mg thrice a day, adjusted to the lowest dose required to relieve symptoms
Nausea and vomiting0.5mg per pound body weight adjusted to patient’s age and severity of the condition
Motion sickness12.5mg to 25mg twice daily
Sedation12.5mg to 25mg at bedtime
Pre-and post-operative use as a calming agent12.5mg to 25mg

Note: Promethazine HCl syrup contains 5-6.25mg drug per 5ml of liquid. Dosage to be calculated accordingly (5). Promethazine suppositories and tablets are available in 12.5mg dosage. Consult a doctor to know the best form of Promethazine for your child’s condition.

What Are The Side Effects Of Promethazine In Children?

Promethazine may have the following common side effects (2).

  • Drowsiness
  • Dry mouth
  • Sleep disturbances
  • Nightmares
  • Nervousness
  • Excitability
  • Ringing in ears
  • Stuffy nose
  • Blurred vision

Seek medical advice if these become severe or are not resolved in a few days. Serious adverse effects that need immediate medical help include:

  • Wheezing or difficulty breathing
  • Slowed breathing or breathing stops for a short time
  • Fever
  • Sweating
  • Irregular or increased heart rate
  • Low blood pressure
  • Muscle stiffness
  • Fainting
  • Uncoordinated movements or unusual face and tongue movement
  • Hallucinations
  • Confusion
  • Seizures
  • Involuntary shaking of body parts
  • Unusual bruising or bleeding
  • Yellow skin or eyes
  • An allergic reaction (rash, hives, swelling of the face, eyes, lips, tongue, throat, arms, hands, feet, ankles, or lower legs)

Neuroleptic malignant syndrome (NMS) is a rare yet potentially fatal side effect of Promethazine. Contact a doctor immediately if you see symptoms such as fever, muscle cramps, severe headache, confusion, increased or abnormal heartbeat, or excess sweating.

What Are The Precautions To Be Taken When Using Promethazine?

Promethazine has several side effects that mandate precautions for safe usage of Promethazine in children (6).

  • Inform the doctor if your child has respiratory problems, such as asthma, chronic obstructive pulmonary disease (COPD) or sleep apnea, liver disorders or Reye’s syndrome, or allergy to sulfites. Promethazine might be contraindicated for children with these conditions.
  • Promethazine increases the likelihood of seizures. Talk to the doctor if your child is prone to or has had seizures in the past.
  • Discuss with your child’s doctor if your child is on any other medicines, health supplements, or herbal products. Phenothiazine may have drug interactions. Conversely, inform the healthcare provider about your child’s Promethazine usage when seeking medication for any other condition.
  • Refrain from involving your child in activities requiring alertness, such as riding a bike or skateboarding, since Promethazine may cause drowsiness and diminished alertness as a side effect.
  • Monitor blood sugar in children with diabetes.
  • Make sure to use only the prescribed dose for the duration instructed. Do not suddenly stop or increase the dose without consulting a doctor.
  • Use the measuring tool provided with the package for syrups to ensure the correct dosage.
  • Check the list of ingredients of all other medicines/products administered to the child to avoid an accidental overdose of Promethazine.
  • Make sure to check the ingredient list to spot any inactive ingredients that may cause allergies in your child.
  • Promethazine may make your child’s skin more sensitive to sunlight. Use sunscreens or protective clothing whenever your child needs to go out in the sun.
  • Keep the medication out of children’s reach in child-proof containers. Accidental overdose can be fatal.

Promethazine is effective in children when used with caution and under medical guidance. Second-generation antihistamines such as Cetirizine (Zyrtec), Loratadine (Claritin), and Fexofenadine (Allegra) have fewer adverse effects. They may be considered as alternatives to Promethazine (7). Ondansetron (Zofran) is an effective antiemetic in children aged four years and above (8). Consult a pediatrician to know what is best for your child’s health condition.

Key Pointers

  • Promethazine is an antihistamine drug to manage allergies, motion sickness, nausea, vomiting, sedation, etc.
  • The FDA recommends against using promethazine for children under two years and suggests cautious use for children above two years.
  • Drowsiness, dry mouth, nightmares, blurred vision, etc., are a few side effects of promethazine in children.


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Dr. Salla Semmane

Dr. Salla Semmane is a practicing pediatrician in Rabat in the district of Hassan, Morocco. Born in Finland, she completed her medical studies at the Faculty of Medicine in Kuopio and had her Licentiate of Medicine in 1989. She received the right of a specialist in pediatrics in 1998 and moved to Morocco in 2000. Dr. Semmane is registered at... more

Dr. Joyani Das

Dr. Joyani Das is a PhD in Pharmacology with over two years of experience in academics. Previously, she worked as an associate professor, faculty of Pharmacology. With her research background in preclinical studies and a zeal for scientific writing, she joined MomJunction as a health writer. Her research work was published in international journals and publications, such as Elsevier, Current... more