Phenergan (promethazine) is a sedating antihistamine used to relieve allergy symptoms, hives, nausea, and travel sickness, and sometimes for short-term sleep under medical supervision. It causes marked drowsiness, so do not drive after taking it, and do not combine it with alcohol or other sedatives. It is strictly prohibited under the age of two because it can slow or stop breathing. Older adults and pregnant women need a doctor's decision before using it.
What is Phenergan and how does it work?
The active ingredient in Phenergan is promethazine. It is a "sedating" antihistamine, meaning it causes drowsiness more than some other antihistamines [1]. It belongs to a drug class called phenothiazines [4]. You will find the drug in our drug directory under two similar spellings: the Phenergan page and the Phenergan (alternate spelling) page, which refer to the same medicine.
Allergy is an immune system response to a substance that does not bother most people, such as pollen, dust mites, or certain medications [5]. Promethazine only relieves symptoms. It does not treat the underlying cause or speed up recovery [4].
Promethazine is available as tablets or as an oral liquid [1]. The tablets come in 10, 20, or 25 mg strengths, and the liquid contains 5 mg per 5 mL [2]. In Jordan, the Jordan Food and Drug Administration (JFDA) regulates medicines and their listed prices, so ask your pharmacist about the form and strength available to you.
Why is Phenergan used: allergies, nausea, or sleep?
Doctors prescribe it, or pharmacists recommend it, for specific conditions:
- Allergies: such as hay fever and hives (urticaria) [1], allergic rhinitis, allergic conjunctivitis, and allergic skin reactions [4]. If your symptoms are seasonal nasal symptoms, see the allergic rhinitis page.
- Nausea, vomiting, travel sickness, and dizziness (vertigo): [1]. It is also used to prevent nausea and vomiting after surgery [4].
- Sedation before and after surgery: [4].
- Short-term situational insomnia: the drug information on ClinicsJo lists it among its approved uses.
- Itching caused by cholestasis of pregnancy (a liver-related bile flow problem): a doctor may sometimes prescribe it if the itching prevents sleep [1].
Vomiting in children is not routinely treated with it. It is only used in special cases decided by a doctor [4]. Recurrent nausea with no clear cause needs a diagnosis, not open-ended use of the drug. You can find details on causes and warning signs in the article Nausea and Vomiting: Causes and When to See a Doctor.
Why is Phenergan prohibited under the age of two?
The most important warning in medical references is that promethazine can slow or stop breathing, and can cause death in children. For this reason, it must not be given to infants or children under two years old, and it is used with caution in older children [4]. The ClinicsJo drug information confirms the same point: it is strictly prohibited under the age of two.
Other notes for parents:
- Tell your child's doctor if they have a condition that affects breathing, such as lung disease, asthma, or sleep apnea [4].
- Tell the doctor about all medications the child is taking, especially sedatives, hypnotics, and narcotic painkillers [4].
- Combination products that contain promethazine and codeine must not be given to anyone under 16 years old [4].
- If the child is vomiting, lethargic, drowsy, or appears dehydrated, inform the doctor before giving any dose [4].
Children are more prone to side effects such as tension and agitation [3]. Giving the drug as a "sleep syrup" to calm a child during long trips is not acceptable, as it is a dangerous practice that medicine rejects. For children over two, the dose is based on body weight and prescribed by a doctor or recommended by a pharmacist. Do not guess the dose, and do not give a child a medicine prescribed for a sibling. See the answer to Can I use a prescription medication prescribed for another family member?.
If your child is under two and has allergies or vomiting, consult a pediatrician or the Mother and Child Health Center of the Ministry of Health in your area. To plan nutrition for this stage, read Infant Nutrition from Birth to Two Years.
How is promethazine taken? Forms and usual doses
The usual dose set by the doctor or pharmacist varies depending on the reason for use. The table below summarizes what the UK National Health Service (NHS) reference lists for adults and people aged 10 years and older. It is for information only and does not replace a doctor's prescription or the instructions on your medicine package:
| Reason for use | Range stated in the reference |
|---|---|
| Hay fever or hives | From 10 mg twice daily up to 20 mg three times daily, or 25 mg once or twice daily |
| Prevention of travel sickness | Usually 25 mg the night before travel; some products are taken one to two hours before a short journey |
| Treatment of travel sickness once it occurs | 25 mg as soon as possible and 25 mg in the evening of the same day, then 25 mg in the evening of the next day if needed |
| Dizziness (vertigo) | From 25 mg daily up to 25 mg four times daily |
Source: [2]. Other references differ on the timing for preventing travel sickness, as some state it should be taken about 30 to 60 minutes before travel [4]. Therefore, follow what is written on your product's package or what your doctor and pharmacist tell you. Doses are lower for those aged 9 years or younger [2].
Practical tips for use
- It can be taken with or without food. Swallow tablets whole with water, without chewing [2].
- Measure the liquid with the syringe or spoon provided. Do not use a kitchen spoon, as it does not give the correct amount [2].
- Do not take it for longer than a short period unless your doctor allows otherwise [2].
- If you miss a dose: if you use it for travel sickness, take it as soon as you remember; otherwise, skip the missed dose and take the next one at the scheduled time. Never double the doses [2].
- If you have used it for a long time, do not stop it suddenly. You may feel dizziness, sweating, nausea, palpitations, or difficulty sleeping. Speak to your doctor so they can reduce the dose gradually [2].
Can I drive or drink alcohol while taking Phenergan?
Do not drink alcohol while taking promethazine, as alcohol increases the risk of side effects [1]. Do not drive a car or motorcycle, or operate machinery, if you feel drowsy or dizzy [1]. Drowsiness usually wears off within 12 hours of a dose [3], but the effect of an evening dose may extend into the morning. Therefore, do not drive in the morning after a night dose unless you are sure you are fully alert. Treat it as a sleep aid even if you take it for allergies or nausea, and plan your next day accordingly.
Important interactions
The effects of promethazine add to those of other medicines that depress the central nervous system. These include hypnotics, sedatives, narcotic painkillers, anxiety medications, and barbiturates [4], as well as benzodiazepines according to the drug information. Other drugs with anticholinergic effects may increase dryness, constipation, and urinary retention, and monoamine oxidase inhibitors (MAOIs) can increase its effects.
Make a list of all medications, vitamins, and supplements you take, and show it to your doctor and pharmacist at every visit [4]. Tell your doctor and the laboratory that you are taking it before any test [4]. It may interfere with skin allergy tests, and a gap of about 4 days is needed, according to the drug information on the ClinicsJo directory. It may also affect the results of home pregnancy tests [4].
What are the common and serious side effects?
Common side effects include drowsiness, headache, nightmares, dizziness, confusion or insomnia, and anxiety [1]. The drug information also lists dry mouth, blurred vision, constipation, and urinary retention. The table below explains how to manage them:
| Symptom | Recommended action |
|---|---|
| Fatigue and daytime drowsiness | Do not drive or use machinery or tools; it usually wears off within 12 hours [3] |
| Nightmares | Consult your pharmacist or doctor if they continue or bother you [3] |
| Dizziness, loss of balance, or poor concentration | Stop your activity and sit or lie down. If it does not go away, do not take extra doses and consult your doctor or pharmacist [3] |
| Headache | Rest and drink fluids. Consult your doctor if it lasts more than a week or becomes severe [3] |
The drug can also make the skin more sensitive to the sun, so avoid prolonged direct exposure to strong sunlight [3].
Symptoms that require immediate medical attention
- Confusion or clouded thinking, blurred vision, or difficulty urinating [3].
- Yellowing of the eyes or skin, or bruising and bleeding more than usual [3].
- Muscle stiffness, tremors, or abnormal movements of the face and tongue [3].
- Rapid or irregular heartbeat [3].
- In children: aggression, hallucinations, or hyperactivity [3].
In these cases, the drug is stopped on the doctor's instructions after contacting them. Do not make this decision on your own.
Who needs special caution: older adults, pregnant women, and people with chronic conditions?
Older adults: Promethazine is generally not recommended for people aged 65 years and older, because it is less safe than other medicines that treat the same conditions [4]. Its side effects include confusion and dizziness [1], which increase the risk of falls in older people. The drug information describes caution as especially important in this group. If it is prescribed for your father or mother, ask the doctor about suitable alternatives for their condition.
Pregnancy and breastfeeding: Tell your doctor if you are pregnant, planning a pregnancy, or breastfeeding. If you become pregnant while using it, contact your doctor [4]. A doctor may sometimes prescribe it for itching in pregnancy linked to the liver problem mentioned earlier [1]. The pregnancy category in the drug information is C, meaning the decision rests with the doctor after weighing benefit against risk. Do not start it or stop it on your own.
Conditions to report to your doctor before use: enlarged prostate, glaucoma, seizures (epilepsy), ulcers, bladder or gastrointestinal obstruction, asthma and lung disease, sleep apnea, heart and liver disease, and bone marrow disorders [4]. The drug information lists narrow-angle glaucoma and urinary retention among the contraindications. If you have weak urine flow, read Benign Prostatic Hyperplasia: Weak Urine Flow and Treatment.
If you are allergic to promethazine or other phenothiazines, or if you have previously had an unexpected reaction to any medicine, tell your doctor [4]. To learn about drug allergies, read the drug allergy page. Your doctor may discuss suitable alternatives for your condition, including other antihistamines such as Avil (pheniramine), which is listed in the drug directory.
When should you see a doctor, and when should you call emergency services?
See a doctor if:
- Allergy, nausea, or dizziness symptoms continue despite the medicine, or recur without a clear cause [4].
- Side effects bother you or do not go away [3].
- You want to use it for longer than the leaflet specifies [2].
Call 911 or go to the nearest emergency department if:
- Signs of a severe allergic reaction (anaphylaxis) appear: swelling of the lips, mouth, throat, or tongue; difficulty breathing or swallowing; blue or pale skin or lips; or sudden dizziness and confusion [3].
- Someone takes a dose larger than recommended and develops severe palpitations, difficulty breathing, a seizure, loss of consciousness, involuntary movements, or hallucinations [2].
- A child takes an overdose and begins walking unsteadily or without balance [2].
- A child develops difficulty breathing, wheezing, or pauses in breathing [4].
- A person collapses or cannot be woken [4].
Do not drive yourself to the emergency department. Ask someone else to take you, or call an ambulance. Take the medicine package or leaflet, any remaining medicine, and any other medications you are taking with you [2]. Even if no symptoms appear after an overdose, contact the appropriate professionals for advice [2].
How do I find the right doctor or clinic in Jordan?
Choosing the right specialty starts with the reason you are using Phenergan:
- Recurrent allergies, chronic urticaria, or drug allergy: an allergy and immunology specialist, or a general internist or family physician as a starting point.
- Persistent nausea or dizziness: a general internist or family physician, who may refer you to an ENT (ear, nose, and throat) or neurology specialist depending on the case.
- A child who needs medication: a pediatrician. You can also inquire at the Mother and Child Health Centers of the Ministry of Health, located across the governorates.
You can browse the Food and Drug Allergy Clinics Directory in Jordan or the Amman Food and Drug Allergy Clinics Directory, then filter results by specialty and governorate. You can also view the Allergy Education and Prevention service. Where your profile allows it, you can contact a doctor or book an appointment through ClinicsJo.
What to check in a doctor's profile
- Listed specialty and experience, governorate, address, and working hours.
- Whether they see children or older adults, if the condition concerns one of them.
- Available means of contact or booking.
Questions to ask at the appointment
- Is promethazine suitable for my condition, or are there less sedating alternatives?
- How long should I use it, and what is my usual dose? (For a child: what is the dose based on their weight?)
- Does it interact with my current medications, or with pregnancy or breastfeeding?
- What signs mean I should stop it, contact you, or go to the emergency department?
Summary: how do you use this medicine safely?
Phenergan is useful when it is used for a clear reason, for a short period, and at the dose set by the doctor or pharmacist. Treat it as a sleep-inducing medicine, avoid driving and alcohol, and consult a doctor if you are older, pregnant, or have chronic conditions. Never give it to a child under two, regardless of the reason. If you have doubts about your condition, diagnosis comes before continuing the medicine.
Frequently asked questions
Does Phenergan cause drowsiness?
Yes. It is a sedating antihistamine, and drowsiness is one of its most common side effects. It usually wears off within about 12 hours of a dose, but the effect of an evening dose may extend into the morning. Therefore, do not drive or operate machinery if you feel drowsy or dizzy, and plan your next day as if you had taken a sleep aid.
Why is Phenergan prohibited for children under two?
Because promethazine can slow or stop breathing in infants and young children, and it can lead to death. For this reason, it is strictly prohibited under the age of two. After this age, it is used with caution, on a doctor's prescription or a pharmacist's recommendation, and based on the child's weight. It is never used to put a child to sleep during travel.
Can I drink alcohol with Phenergan?
This is not recommended. Alcohol increases the risk of the drug's side effects and can intensify drowsiness and dizziness. The same applies to hypnotics, sedatives, narcotic painkillers, and anxiety medications, as their effects add to those of promethazine. Tell your doctor or pharmacist about everything you take before starting.
Is Phenergan safe during pregnancy?
Do not decide this on your own. Tell your doctor if you are pregnant, planning a pregnancy, or breastfeeding, as the doctor is the one who weighs benefit against risk. Sometimes a doctor prescribes it for pregnancy-related itching caused by a liver problem if the itching prevents sleep. The drug may also affect the results of home pregnancy tests.
Is it suitable for older adults?
It is generally not given to people aged 65 years and older, because it is less safe than other medicines that treat the same conditions. It may cause confusion and dizziness that increase the risk of falls. If it is prescribed for an older person, the doctor should discuss the benefits and alternatives, especially if they have an enlarged prostate or glaucoma.
What should I do if I take an overdose of Phenergan?
Contact your doctor or pharmacist immediately, even if no symptoms appear. If severe palpitations, difficulty breathing, a seizure, loss of consciousness, hallucinations, or involuntary movements occur, call 911 or go to the nearest emergency department. Do not drive yourself, and take the medicine package with you.
Sources and references
- About promethazine — NHS (UK National Health Service). Accessed: 2026-10-26.
- How and when to take promethazine — NHS (UK National Health Service). Accessed: 2026-10-26.
- Side effects of promethazine — NHS (UK National Health Service). Accessed: 2026-10-26.
- Promethazine: MedlinePlus Drug Information — MedlinePlus — U.S. National Library of Medicine. Accessed: 2026-10-26.
- Allergies | Hypersensivity — MedlinePlus — U.S. National Library of Medicine. Accessed: 2026-10-26.