Promethazine Uses, Dosage, Side Effects, Food Interaction and all others data.

Promethazine Theoclate works by stopping histamine from binding to its receptors in an area in the brain known as the vomiting centre. The vomiting centre is responsible for causing feelings of sickness and for the vomiting reflex. It is activated when it receives nerve messages from the vestibular apparatus in the middle ear.

The vestibular apparatus provides constant feedback to the brain about the position of our body. When something disturbs the vestibular apparatus, such as movements of the head when travelling by boat or car, nerve signals are sent from the vestibular apparatus to the vomiting centre. This can cause the symptoms of motion sickness, such as nausea, dizziness or spinning sensations (vertigo) and vomiting.

By blocking the histamine receptors in the vomiting centre, Promethazine Theoclate prevents disturbances in the middle ear from activating the vomiting centre.

Promethazine is is a histamine H1 antagonist that can be used for it's ability to induce sedation, reduce pain, and treat allergic reactions. Promethazine's effects generally last 4-6h but can last up to 12h. Patients should be counselled regarding CNS and respiratory depression, reduce seizure threshold, and bone marrow depression.

Trade Name Promethazine
Availability Prescription only
Generic Promethazine
Promethazine Other Names Proazamine, Prometazina, Promethazine, Promethazinum
Related Drugs prednisone, trazodone, hydroxyzine, lorazepam, ondansetron, cetirizine, loratadine, fluticasone nasal, diazepam, montelukast
Weight 25mg/5ml, , 25mg/25ml + nacl0.9%, 25mg/ml, 50mg/ml, 12.5mg, 25mg, 50mg, 2%, 50mg/2ml, 5mg/5ml
Type Elixir, Tablet, Injectable Solution, Injection, Rectal Suppository, Rectal, Cream, Syrup
Formula C17H20N2S
Weight Average: 284.419
Monoisotopic: 284.13471934
Protein binding

Promethazine is 93% protein bound in serum, mostly to albumin.

Groups Approved, Investigational
Therapeutic Class Anti-emetic drugs, Miscellaneous sedatives & hypnotics, Sedating Anti-histamine
Manufacturer Hizat Pharmaceutical Industries (pvt) Ltd, , Ifars, Anhui Chengshi Pharmaceutical Co Ltd, Mars Remedies Pvt Ltd, Drugfield Pharmaceuticals Limited
Available Country Pakistan, United States, Indonesia, Netherlands, China, Nigeria, India
Last Updated: September 19, 2023 at 7:00 am


Promethazine Theoclate Tablets are an anti-emetic (anti-sickness drug) which helps to prevent, and treat nausea and vomiting, including travel sickness, and vertigo. Promethazine Theoclate contains promethazine which belongs to a group of medicines called phenothiazines. Your doctor may prescribe this medicine for giddiness or light-headedness (vertigo), or for sickness after an operation, and in such cases the tablets should be taken as instructed by your doctor.

Promethazine is also used to associated treatment for these conditions: Allergic urticaria, Anaphylaxis, Cough, Dermographism, Motion Sickness, Nasal Congestion, Postoperative pain, Seasonal Allergic Conjunctivitis, Seasonal Allergic Rhinitis, Vasomotor Rhinitis, Acute Allergic Reactions, Dry cough, Perioperative nausea and vomiting, Upper respiratory symptoms, Sedative therapy, Adjunct to anesthesia and analgesia

How Promethazine works

Promethazine is a an antagonist of histamine H1, post-synaptic mesolimbic dopamine, alpha adrenergic, muscarinic, and NMDA receptors. The antihistamine action is used to treat allergic reactions. Antagonism of muscarinic and NMDA receptors contribute to its use as a sleep aid, as well as for anxiety and tension. Antagonism of histamine H1, muscarinic, and dopamine receptors in the medullary vomiting center make promethazine useful in the treatment of nausea and vomiting.


Promethazine dosage

To prevent travel sickness on short journeys: Promethazine Theoclate should be taken at least one or two hours before travelling. Adults and children aged over 10 yearsshould take one tablet. Children aged 5 to 10 years should be given half a tablet.

To prevent travel sickness onlong journeys: Promethazine Theoclate should be taken at bedtime each night during the journey, startingthe night before you travel.Adults and childrenaged over 10 yearsshould take one tablet.Children aged 5 to 10 years should be given half a tablet.

To treat travel sickness:Adults and children over 10 years should take one tablet as soon as you feel sick, followed by a second tablet the same evening. Take a third tablet the following evening if necessary. Children aged 5 to 10 years should treated in the same way, but with half a tablet each time.

For sickness and vomiting due to other causes, and for treating vertigo: Adults and children aged over 10 years should take one tablet up to three times aday. Children aged 5 to 10 years should be given half a tablet up to three times a day.Alternativelyyou should follow the instructions given by your doctor.

Side Effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with promethazine. Just because a side effect is stated here does not mean that all people using Promethazine Theoclate will experience that or any side effect.

  • Drowsiness or feeling tired.
  • Dizziness.
  • Restlessness.
  • Headache.
  • Nightmares.
  • Blurred vision.
  • Difficulty passing urine.
  • Dry mouth.
  • Confusion.
  • Feeling disorientated.
  • Unexpected increase in excitability in children.
  • Increased sensitivity of the skin to sunlight (photosensitivity). If affected you should avoid sun lamps and direct sunlight while you are taking this medicine.
  • Loss of appetite.
  • Awareness of your heartbeat (palpitations).
  • Abnormal heartbeats (arrhythmias).
  • Low blood pressure (hypotension).
  • Abnormal movements of the hands, legs, face, neck and tongue, eg tremor, twitching, rigidity (extrapyramidal effects).
  • Blood disorders.


The intraperitoneal LD50 in rats is 170mg/kg and in mice is 160mg/kg. The subcutaneous LD50 in rats is 400mg/kg and in mice is 240mg/kg. The oral LD50 in mice is 255mg/kg.

Patients experiencing an overdose of promethazine may present with mild central nervous system and cardiovascular depression, hypotension, respiratory depression, unconciousness, hyperreflexia, hypertonia, ataxia, athetosis, extensor-plantar reflexes, convulsions, dry mouth, flushing, gastrointestinal symptoms, and fixed, dilated pupils. Treat overdoses with symptomatic and supportive treatment, which may include activated charcoal, sodium sulfate, magnesium sulfate, controlled ventilation, diazepam, intravenous fluids, vasopressors, norepinephrine, phenylephrine, anticholinergic antiparkinsonian agents, diphenhydramine, barbiturates, or oxygen.


Promethazine Theoclate tablets can make some people feel drowsy, dizzy, confused or disorientated and this may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance. If your child is affected in this way they should avoid potentially hazardous activities such as riding bikes. You should not leave your child unattended after giving them this medicine.

Avoid drinking alcohol while taking Promethazine Theoclate because this is likely to make the above effects more likely or worse.

Promethazine Theoclate tablets may make your skin more sensitive to sunlight than usual, so you should avoid exposing your skin to direct sunlight or sunlamps until you know how your skin reacts. If you can't avoid strong sunlight you should use a sunscreen lotion or make sure your skin is protected with clothing.

This medicine may interfere with some pregnancy tests, causing false negative or false positive results.

If you are due to have any skin prick tests to diagnose allergies you should stop taking Promethazine Theoclate at least 72 hours before the tests. This is because antihistamines can prevent or lessen the skin reactions that indicate an allergy, and so can make the test results unreliable.


It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start taking Promethazine Theoclate. Similarly, check with your doctor or pharmacist before taking any new medicines while taking Promethazine Theoclate, to make sure that the combination is safe.

Promethazine Theoclate should not be taken by anyone who has taken a type of antidepressant called a monoamine oxidase inhibitor (MAOI), eg phenelzine, tranylcypromine, isocarboxazid, in the previous 14 days.

You are more likely to feel drowsy if you take Promethazine Theoclate with any of the following (which can also cause drowsiness):

  • alcohol
  • antipsychotic medicines, eg chlorpromazine
  • barbiturates, eg phenobarbital
  • benzodiazepines, eg diazepam, temazepam
  • sedating antihistamines, eg chlorphenamine, brompheniramine, hydroxyzine
  • sleeping tablets, eg zopiclone
  • strong opioid painkillers, eg morphine, codeine, dihydrocodeine, tramadol
  • tricyclic antidepressants, eg amitriptyline.

Food Interaction

  • Avoid alcohol. Alcohol may increase the sedation caused by promethazine.

Promethazine Alcohol interaction


Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment.

Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines.

The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.

Patients should be advised to avoid alcohol during phenothiazine therapy.

Volume of Distribution

The volume of distribution of promethazine is approximately 970L or 30L/kg.

Elimination Route

A 25mg dose of intramuscular promethazine reaches a Cmax of 22ng/mL. Intravenous promethazine reaches a Cmax of 10.0ng/mL, with a Tmax of 4-10h, and an AUC of 14,466ng*h/mL. Oral promethazine is only 25% bioavailable due to first pass metabolism. Oral promethazine reaches a Cmax of 2.4-18.0ng/mL, with a Tmax of 1.5-3h, and an AUC of 11,511ng*h/mL.

Half Life

The elimination half life of promethazine is approximately 12-15h.


The intravenous clearance of promethazine is approximately 1.14L/min. The renal clearance of promethazine is 5.9mL/min and the renal clearance of promethazine sulfoxide is 90.4mL/min.

Elimination Route

An intravenous dose of promethazine is 0.64% eliminated in the urine as the unchanged parent drug, 0.02-2.02% in the urine as desmethylpromethazine, 10% in the urine as promethazine sulfoxide.

Pregnancy & Breastfeeding use

If you are pregnant you should not take Promethazine Theoclate without consulting your doctor first. Promethazine Theoclate should only be used during pregnancy if essential, and only if the expected benefit to the mother outweighs any potential risks to the developing baby. It should not be used during the last two weeks of pregnancy, because if taken during this time it may cause irritability or excitement in the baby after birth. Seek further medical advice from your doctor.

Small amounts of Promethazine Theoclate may pass into breast milk. This is not expected to be harmful to a nursing infant with occasional short-term use of Promethazine Theoclate, but there is a risk that it may cause drowsiness, irritability or excitement in a newborn baby. If you are breastfeeding you should not take Promethazine Theoclate without getting medical advice from your doctor first.


  • Children under five years of age.
  • People with reduced awareness, slow reactions or extreme drowsiness caused by medicines or illnesses that reduce activity in the central nervous system.
  • People who have taken a type of medicine called a monoamine-oxidase inhibitor antidepressant (MAOI) in the past 14 days.
  • Children and adolescents who have signs and symptoms suggestive of Reye's syndrome.
  • People who are allergic to any ingredients of the tablets.
  • Promethazine Theoclate tablets contain lactose and should not be taken by people with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption.

Storage Condition

Store between 15-30° C. Protect from light.

Innovators Monograph

You find simplified version here Promethazine

Promethazine contains Promethazine see full prescribing information from innovator Promethazine Monograph, Promethazine MSDS, Promethazine FDA label


What is Promethazine used for?

Promethazine is used to relieve the symptoms of allergic reactions such as allergic rhinitis, allergic conjunctivitis (red, watery eyes caused by allergies), allergic skin reactions, and allergic reactions to blood or plasma products.

How safe is Promethazine?

Promethazine may cause breathing to slow or stop, and may cause death in children.It should not be given to babies or children who are younger than 2 years old and should be given with caution to children who are 2 years of age or older.

How does Promethazine work?

Promethazine works by changing the actions of chemicals in your brain.Promethazine also acts as an antihistamine. It blocks the effects of the naturally occurring chemical histamine in your body.

What are the common side effects of Promethazine?

Common side effects of Promethazine are include :

  • dry mouth
  • drowsiness
  • listlessness
  • difficulty falling asleep or staying asleep
  • nightmares
  • dizziness
  • ringing in ears
  • blurred or double vision
  • loss of coordination
  • nausea
  • vomiting
  • nervousness
  • restlessness
  • hyperactivity
  • abnormally happy mood
  • stuffy nose
  • itching

Is Promethazine safe during pregnancy?

Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Promethazine should be used during pregnancy only if the benefit outweighs the risk to the fetus.

Is Promethazine safe during breastfeeding?

Short-term use of Promethazine for the treatment of nausea and vomiting poses little risk to the breastfed infant.

Can I drink alcohol with Promethazine?

Do not drink alcohol while you're taking Promethazine. Alcohol and Promethazine together can make you sleep very deeply. You will not be able to breathe properly and may have difficulty waking up.

Can I drive after taking Promethazine?

You should avoid driving or operating heavy machinery until you know how it affects you. 

When should I take Promethazine?

Take Promethazine 20 minutes before you go to bed. It normally takes about 30 minutes to work. To prevent motion sickness, take Promethazine the night before a long journey or 1 to 2 hours before a short journey.

How long does it take Promethazine to work?

Clinical effects are apparent within 20 minutes after oral administration and generally last four to six hours, although they may persist as long as 12 hours.

How long does Promethazine last?

Promethazine last about 15 minutes to avoid having the suppository come out. Do not use more often than directed.

How long can I take Promethazine?

Only take Promethazine for a short time, unless your doctor says it's safe for you to take it for longer.

Is Promethazine addictive?

Promethazine addiction is dangerous and harmful to a person's well-being. By opting in for recovery, individuals can learn to live free from the Antihistamine. Thousands of people have successfully recovered from addiction.

Can I take Promethazine for anxiety?

Promethazine may be used to help people go to sleep and control their pain or anxiety before or after surgery or other procedure.

How long does Promethazine stay in my system?

Promethazine will be mostly out of your system in two to four days . The elimination half-life of a medication is the time it takes for blood levels of the medication to be reduced by half.

Who should not take Promethazine?

Promethazine should not be given to babies or children who are younger than 2 years old and should be given with caution to children who are 2 years of age or older. Combination products containing Promethazine and codeine should not be given to children younger than 16 years old.

Is Promethazine a narcotic?

Technically, no, Promethazine is not a narcotic, a term that's frequently misused, often interchangeably as a reference to any sort of illegal substance.

What happens if I miss a dose of Promethazine?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose of Promethazine ?

Seek emergency medical attention.Overdose symptoms may include overactive reflexes, loss of coordination, severe drowsiness or weakness, fainting, dilated pupils, weak or shallow breathing, or seizure.

What happens when I stop taking Promethazine?

Some of the most common withdrawal symptoms from Promethazine and codeine include: Restless legs,Insomnia, Pain.
*** Taking medicines without doctor's advice can cause long-term problems.