Promethazine (Oral)

Promethazine is a tablet that is taken in an oral pill form in order to treat a variety of symptoms, including nausea and vomiting and symptoms of allergies.


The pill form of Promethazine is used to treat a variety of symptoms, most commonly those for nausea and vomiting that are caused by issues such as surgery, other medical procedures, or motion sickness. Sometimes it is taken along with other painkillers and medicines given before and after surgery to help in their effects and also to make the patient more relaxed. It can aid some painkillers and anesthetics in sedating a patient for surgeries as well as calming their anxiety about the surgery. It can also treat mild symptoms of non-life-threatening allergies such as runny nose or inflammation of the eye that is brought on due to allergies. Occasionally it could be used as adjunctive therapy alongside epinephrine in more severe allergic reactions. Promethazine can also sometimes be administered in a liquid format. Promethazine is also known by several brand names, as Promethazine is the generic name for the drug. Some of the brand names are called Phenergen or Promacot.

It is known as a neuroleptic medicine, drugs that act on various parts of the nervous system to reduce nervous tension, and also can act as an antihistamine, drugs that prevent allergic reactions. Promethazine works by blocking histamine, a natural product that your body makes while it is having an allergic reaction. It also works to reduce nausea and relax a patient by interacting with some chemicals in the brain that trigger these effects.

Conditions Treated

  • Nausea and vomiting caused by certain sicknesses or conditions.
  • Some symptoms of allergies.
  • Symptoms of hay fever or eye irritation due to allergies.
  • Common cold.
  • Aid in some uses of painkillers.

Type of Medication

  • Antihistamine
  • Neuroleptic

Side Effects

Some of the common side effects of Promethazine can include the following:

Sometimes, though rarely, some more serious side effects can occur while taking this medicine. If you experience any of the following side effects, please contact your doctor right away:

  • Irregular mental or mood changes that can include hallucination and insomnia
  • Abnormal uncontrollable movements
  • Fainting or extreme dizziness
  • Slowed heartbeat
  • Difficulty urinating
  • Pale or blue skin, lips, and fingernails
  • Jaundice
  • Severe stomach or abdominal pain
  • Signs of any infection such as fever or rash
  • Easily bleeding or bruising
  • Persistent and severe nausea or vomiting
  • Shaking, tremors, or convulsions

Medical attention should be sought immediately if any of the following very severe and serious side effects occur:

  • Slowed or very shallow breathing, or other signs of a condition known as respiratory depression
  • Seizure

While it is rare, this medication is known to potentially cause a serious condition known as neuroleptic malignant syndrome. Seek medical attention immediately if you have the following symptoms of neuroleptic malignant syndrome:

  • Muscle pain, tenderness, or weakness
  • Severe mental changes, especially confusion
  • A fast or irregular heartbeat
  • Changes in urine, such as less urine than normal or much darker urine than normal
  • Fever
  • Fatigue
  • Sweating

Serious allergic reactions to this medication are very rare, but they are known to occur. If you experience any of the following symptoms of a severe allergic reaction, seek medical attention immediately:

  • Swelling of the face, tongue, and throat
  • Severe dizziness
  • Rash
  • Trouble breathing

This medication can cause overdosing. If you suspect someone of an overdose and they are experiencing severe side effects, seek medical attention immediately. Otherwise, contact your doctor for less severe side effects. Some of the side effects of overdose can include:

  • Fainting
  • Seizure
  • Widened pupils
  • Severe drowsiness
  • Severe dizziness
  • Slowed or shallower breathing
  • Muscle twitching


This medication is taken orally, normally two to four times a day as directed by your doctor, depending on what it is being used to treat. It can be taken with or without food as directed by your doctor. Sometimes taking the medication with food can decrease feelings of stomach irritation after the medication is taken. Because it can cause drowsiness, if it is being used to treat allergies, it should be taken only before bed time. It would normally be taken before and after surgery as directed by your doctor with other medications.

Dosage amount will vary depending on certain factors such as weight, age, and the condition being treated. Take the medication as it is prescribed exactly by your doctor. If you miss a dose, take the missed dose as soon as you realized you have missed it. If it is time for your next dose, take the next dose and do not take the missed dose, and continue your medication as normal. Do not take more than you are supposed to when it is time to take your dose.

Normally when treating allergies, adults or teenagers will take 12.5 mg of Promethazine before meals, spaced evenly throughout the day. 25 mg can also be taken once daily at night if recommended by the doctor. For younger children who must take this medication, the dosage is normally determined by weight and age of the child, and would normally be halved or adjusted as needed based on these factors. Normally after the initial treatment, if more treatment is required, the dosage will be lowered to lower potential side effects.

For motion sickness, a dose of 25 mg is normally taken about an hour before the activity that would cause motion sickness is started. The dose can be repeated twelve hours later if travel is extended or motion sickness persists.

When treating nausea and vomiting, an adult or teenager is normally given 25 mg of Promethazine as an initial dose, with the dose decreasing for subsequent doses and being administered every three to four hours. For younger children who must take this medication, the dosage is normally determined by weight and age of the child, and would normally be halved or adjusted as needed based on these factors.

Normally when this medication is given before and after surgery, a much higher dose of 50 mg might be given to an adult or teenager depending on the type of surgery and other drugs being used to perform the surgery. The same dosage might be also given after the surgery. For children who must take this medication, the dosage is normally determined by weight and age of the child, and would normally be halved or adjusted as needed based on these factors.

Sometimes this medication may be given in liquid form instead of tablet form. In this case, the patient will normally be provided with a spoon or cup to measure the appropriate dose of medication as directed by your doctor.


Some drugs may have potential interactions with this drug. Talk to your doctor about all medications, supplements, vitamins, or other drugs you may be presently taking. Some of the drugs that can have a potential interaction with Promethazine include:

  • Metclopramide
  • Some antihistamines that are applied to the skin, such as creams or ointments.

Some of the following medications can increase your chance for serious side effects or potentially interact in a negative way with Promethazine. It is not recommended that these medications be taken with Promethazine. Talk to your doctor if you are taking any of the medications below or any related medications:

  • Cisapride, bromopride, or related medicines.
  • Sodium oxybate
  • Amifampridine, terfenadine, or related medicines.
  • Dronedarone
  • Mesoridazine, thioridazine, or related medicines.
  • Bepridil

The following medications are not normally paired with Promethazine, but on some occasions their use together may be required. In these types of situations, one or more of the drugs involved may have the dosage changed to prevent serious side effects. There may be more medications or similar types of medications that are not on this list. Talk to your doctor or your pharmacist about the full list of medications that might have negative interactions with your medication.

  • Fentanyl or related drugs
  • Morphine, apomorphine, or other related drugs.
  • Lithium
  • Tramadol
  • Amoxapine, asenapine, or related drugs.
  • Clozapine
  • Sodium phosphate and related derivatives or compounds.
  • Solatol
  • Quinine
  • Orflaxacin and related drugs.
  • Nafarelin
  • Methadone
  • Azithromycin
  • Ketoconazole, fluconazole, and other related drugs.
  • Fluoxetine
  • Donepezil

Some of the following supplements can increase your risk for unwanted side effects if they are taken in tandem with Promethazine. Talk to your doctor about all supplements you are taking to prevent unwanted side effects. Normally they can be taken together, but dosages may need to be changed to decrease the potential for harsher side effects.

  • Belladonna
  • Evening primrose
  • Betel nut
  • Phenylalanine

Some serious side effects, such as slowed or shallow breathing or severe drowsiness and dizziness, can be increased if Promethazine is being taken with other medications that are also known to cause these symptoms. Talk to your doctor about all the medications you are taking. Some of the drugs known to cause these same symptoms can include (but are not limited to):

  • Cough relieves or painkillers that contain opioids, such as codeine or related drugs and hydrocodone or related drugs.
  • Alcohol
  • Marijuana
  • Some muscle relaxants such as carisoprodol and cyclobenzaprines, or other muscle relaxants in the same families as these.
  • Some medications that treat sleep disorders or anxiety disorders, including lorazepam and related drugs.
  • Other antihistamines such as cetirizine.

Along with the drugs above, it is important to check the label on any sort of drug or supplement you may be taking, as there may be other kinds of drugs not listed that are known to cause drowsiness, dizziness, or breathing problems.

This medication can interfere with several different kinds of at home and laboratory tests, causing false results. If you are going to be getting laboratory testing, talk to your doctor or laboratory technician about the drugs you are taking and the possible interactions.


Tell your doctor about your entire medical history, as this medication can interact with some conditions, but especially if you currently have or have a history of the following conditions:

  • Conditions causing breathing problems, such as asthma, sleep apnea, or COPD.
  • com/health/coma/">Glaucoma
  • Heart problems including heart disease or irregular heartbeats
  • Blood or immune system issues, including bone marrow disease
  • Liver disease
  • Neuroleptic malignant syndrome
  • Seizures
  • Reye's syndrome
  • Stomach or intestinal problems
  • Difficult urinating or other kidney related problems
  • High blood pressure
  • Overactive thyroid
  • Enlarged prostate

Most products that treat the common cold have been shown to be unsafe and ineffective in children that are younger than six years old. The only time it should be used on a child is if under the specific direction of a doctor. Talk to your doctor for more information. In the case of Promethazine, it can be potentially dangerous to children that are younger than two years old. Promethazine can cause dangerously shallow breathing in very young children that could be fatal. If your child is taking promethazine under the direction of a doctor and their breathing becomes irregularly shallow or slow, seek medical attention immediately.

Children who have certain liver diseases should avoid this product. Children should also only take the product if the cause of nausea or vomiting is easily identified. Talk to your doctor about your child's medical history before deciding to administer Promethazine.

Elderly adults can still take the medication, but they may be more susceptible to undesirable side effects such as constipation, confusion, and drowsiness. Increased confusion and drowsiness due to this medication puts the elderly at a higher risk for falling. Promethazine can also worsen the symptoms of some diseases such as liver disease or heart disease if these conditions preexist when the patient is elderly as compared to if the patient were younger. If you are an elderly patient with a preexisting condition, your doctor may change your dosage or recommend a different medication.

Pregnant women or those planning to get pregnant should talk to their doctor about using this medication. Normally it would only be used during pregnancy if absolutely needed. There haven't been a substantial number of tests performed on pregnant women to determine the safety of the medication to take during pregnancy, so it is up to your doctor's discretion if the medication is going to be taken during pregnancy. There may be potential risks to the fetus involved. It is unknown if the drug passes through the breast milk into infants; however, because of the potential danger to infants that this drug can cause, it is best to avoid Promethazine while you are breastfeeding.

Promethazine is a drug that is used to treat symptoms only, and will not cure the diseases or symptoms it is prescribed for. Therefore, it is important to carefully follow all dosage directions, and only take Promethazine for short amounts of time. Promethazine can be used alongside other natural treatments or symptom relievers such as saline drops or a humidifier, but patients should talk to their doctor before using Promethazine with other medications normally used to treat symptoms of a cold. It is important to never take more than your prescribed dose, and take the dose exactly as it is prescribed by your doctor.

It is also important to take this medication exactly as prescribed by a doctor because this medication runs the risk of causing a potential overdose. If you suspect someone of overdose and they have severe or potentially fatal symptoms, seek medical attention immediately. Otherwise, contact your doctor or the poison control center. See above for possible symptoms of an overdose.

Talk to your doctor before you begin this medication about your known allergies, including if you are allergic to this medication, allergic to medications in a group of medicines known as phenothiazines, or any other allergies, as some inactive ingredients in medications can cause allergic reactions as well.

Common side effects of this drug are dizziness and blurry vision. While you are taking this medication, avoid tasks that would normally require clear vision and alertness, such as driving or operating heavy machinery. It is best to also avoid alcohol while on this medication, as alcohol can increase these side effects.

While taking this medication, you may experience a heightened sensitive to the sun or to UV rays. It is best to avoid tanning booths while using this medication. When you are outside, limit time in the sun and use sunscreen and protective clothing. Talk to your doctor if you experience severe com/health/burns/">sunburns including skin blisters.

This medication can potentially decrease sweating, which puts you at a higher risk for com/health/heat-stroke/">heat stroke. While taking this medication, avoid activities, such as hard exercise or being outside for a prolonged time in hot weather, or certain locations, such as hot tubs or saunas, that might cause you to overheat. Drink plenty of fluids and dress lightly if you must go outside during hot weather while taking this medication. Seek medical attention immediately if you begin to experience any of the symptoms of heat stroke, such as dizziness, headache, mental changes, or severe fever.

In the liquid form of this medication that is taken orally, there might be some traces of alcohol or sugar in the inactive ingredients. If you have problems with your liver, diabetes, or other sugar or alcohol related conditions, talk to your doctor before taking the liquid form of this medication, as it could affect blood sugar levels.

Remember, your doctor is giving you this medication because they have determined that the benefits will far outweigh the potential side effects. If you have discussed your medical history and your current medications in full with your doctor, as well as taking the medication as it is prescribed to you, you should not experience any severe side effects beyond the common side effects listed. It is also important to keep your doctor updated on your symptoms and condition while this medication is being taken, and talk to your doctor if you are planning any other changes in your health routine, such as starting another medication.


Promethazine is to be stored in its own sealed container at room temperature, and away from sources of heat, direct light, or moisture. Promethazine should not be frozen. If you do not use some of the medication, ask your pharmacist or doctor on how to properly dispose of this medication. Keep this medication out of the reach of children. If medication is past its expiration date, it should not be taken and should instead be disposed of in the proper manner.


Promethazine belongs to a group of medications known as phenoziathines. It is known as a neuroleptic type of medication, meaning it targets certain parts of the brain to relax nervous responses, and is also an antihistamine, which help aid in allergy symptom relief. Promethazine is normally given in the oral route as a pill, though it can also be given in liquid form. Promethazine is indicated to treat several different kinds of conditions, which can include motions sickness, mild allergy relief, relief of anxiety and aiding in sleep before surgery, and aiding in sedation and anxiety relief during and after surgery.

Some of the most common side effects of this drug are dry mouth, dizziness, drowsiness, constipation, and blurry vision. Some more serious side effects can occur, but the most serious side effects (especially in younger or elderly patients) can be severe drowsiness, slowed or shallow breathing, and seizures. If any rare or serious side effects occur, talk to your doctor or seek medical help immediately. Severe allergic reactions to this medication are rare, but if they do occur, seek medical help immediately. Promethazine is not recommended for children, and can be potentially fatal for very young children.

Some conditions can be worsened by Promethezine. It is not recommended for anyone with breathing problems such as asthma, sleep apnea, or COPD to take this medication as the symptoms can be severely worsened by this drug. Patients with a history of neuroleptic malignant syndrome should also not take this medication as Promethazine is known to cause this condition. Those with a history or presently diagnosed with conditions such as liver disease, bone marrow disease, or some brain diseases are also not recommended to take this medication as Promethazine can make these conditions worse.

Heavy machinery should not be operated while on this medication due to the common side effects of drowsiness or blurry vision. Alcohol should not be taken while taking this medication as it can greatly increase these unwanted side effects. This medication can also increase risk of heat stroke and risk of damage from the sun or other UV light sources. This drug in some forms may also make symptoms of diabetes or other blood sugar diseases worse.

There are many drugs that this medication could have negative interactions with, especially drugs like opioids or alcohol. Talk to your doctor about all substances you take before beginning this medication to limit negative side effects.

It is important to talk to your doctor about your entire medical history and all medicines you are taking before you begin taking Promethazine. It is also important to take the medication as it is prescribed to you exactly.