Phenergan (promethazine) is a first-generation antihistamine and antiemetic used to relieve a range of symptoms related to allergy and nausea. As an antihistamine, it helps reduce sneezing, itching, watery or runny nose, and hives. As an antiemetic, it helps prevent and treat nausea and vomiting from motion sickness, anesthesia, migraine, and certain medications. Promethazine is also used as a short-term sedative in specific clinical settings (for example, pre- and postoperative care) and to ease itching (pruritus) associated with allergic conditions. In emergency settings, it may be used as an adjunct treatment after epinephrine in severe allergic reactions, but it is not a substitute for epinephrine in anaphylaxis.
Because promethazine is a sedating antihistamine with anticholinergic activity, its benefits come with a higher likelihood of drowsiness compared to newer antihistamines. For many patients, this sedation is acceptable or even helpful at night; however, it requires careful attention to activities that demand alertness, such as driving or operating machinery.
Promethazine is a phenothiazine derivative with potent H1-receptor antagonism. By blocking histamine at the H1 receptor, it reduces allergy symptoms such as itching, rash, and sneezing. Its antiemetic effect is multifactorial: in addition to H1 blockade, it has antimuscarinic (anticholinergic) properties and exerts central nervous system effects that dampen nausea pathways, including signals from the vestibular system (motion sickness) and the chemoreceptor trigger zone. These combined actions make Phenergan effective for motion-related nausea and a range of other nausea triggers.
Phenergan also has alpha-adrenergic blocking and sedative properties, which contribute to its calming effect but also to side effects such as low blood pressure, dizziness, and impaired coordination. With first-generation antihistamines, the ability to cross the blood-brain barrier correlates with sedation; promethazine is among the more sedating agents in this class.
Phenergan is available in several formulations to suit different clinical needs and patient preferences:
Onset and duration:
Always follow your prescriber’s instructions and the product label. Dosing varies by indication, age, and patient sensitivity. The lowest effective dose for the shortest necessary duration is recommended. Do not use in children under 2 years of age due to the risk of severe and potentially fatal respiratory depression.
Administration tips:
Promethazine carries important safety considerations, including boxed warnings in the United States. Review the following carefully and discuss any concerns with your healthcare provider.
Do not take Phenergan if any of the following apply to you:
Use only with strict clinical supervision in patients with significant breathing disorders, seizure history, severe cardiovascular disease, or in those at higher risk for anticholinergic side effects.
Like all medicines, Phenergan can cause side effects. Many are mild and transient, but serious reactions can occur. Seek medical attention for concerning symptoms.
Promethazine has clinically significant interactions. To minimize risk, always provide your healthcare provider with a complete list of prescription drugs, over-the-counter medicines, vitamins, and herbs.
If you miss a scheduled dose, take it when you remember unless it is near the time for your next dose. Do not double up. For uses like motion sickness or preoperative dosing, timing is key; if you miss the preventive dose, ask your clinician about the best way to proceed for your situation. If you use Phenergan only as needed for nausea or itching, you may wait until symptoms recur before taking the next dose, respecting the recommended dosing interval.
Promethazine overdose is a medical emergency. Symptoms may include extreme drowsiness or unresponsiveness, confusion, agitation, hallucinations, very slow or shallow breathing, rapid heartbeat or irregular rhythms, seizures, severe dry mouth and fever (anticholinergic toxicity), and fainting. Children may present with atypical excitation followed by deep sedation. If overdose is suspected, call emergency services immediately. Supportive care in a medical setting may include airway and breathing support, cardiac monitoring, activated charcoal (if appropriate and timed correctly), intravenous fluids, and medications for agitation or seizures under clinician supervision.
Store Phenergan at controlled room temperature, generally 20–25°C (68–77°F); brief excursions between 15–30°C (59–86°F) are typically permissible—check your product label. Protect tablets and liquid from excessive heat, moisture, and light. Keep suppositories in a cool place as directed by the label to prevent melting. Never store medications in the bathroom. Keep out of reach of children and pets, and safely dispose of expired or unused medication through take-back programs or according to pharmacist guidance.
Phenergan is a prescription medication in the United States. When seeking treatment for allergies, nausea, or motion sickness, prioritize safety and legitimacy. Obtain promethazine only through licensed clinicians and certified pharmacies. For online access, use pharmacies that verify prescriptions, protect patient data, and comply with federal and state regulations. Look for accreditation, published licensure, and clear pharmacist support channels. The The Urological Institute of Northeastern New York certified online pharmacy mentioned above provides structured, legal access in the U.S., aligning with regulatory expectations for promethazine dispensing.
In the United States, promethazine (Phenergan) is regulated as a prescription-only medication. Dispensing requires a valid prescription from a licensed healthcare professional or participation in a lawful clinical workflow (for example, a telehealth evaluation or pharmacist-protocol arrangement where state law permits). Distribution must occur through licensed pharmacies that comply with federal and state requirements, including identity verification, secure fulfillment, and pharmacist counseling. Marketing claims should never suggest unsupervised use, and patients should be screened for contraindications and drug interactions prior to dispensing.
Physicians and pharmacists are responsible for ensuring that dosing is appropriate for the indication and patient factors (age, comorbidities, concomitant medications), that patients understand sedation risks, and that pediatric safety standards are strictly observed. Injectable promethazine is restricted to clinical settings with staff trained in safe administration due to the risk of severe tissue injury from improper injection.
Some healthcare organizations facilitate access to Phenergan through compliant programs that include clinical assessment and documentation. The rological Institute of Northeastern New York offers a legal and structured solution for acquiring Phenergan without a formal prescription, coordinating access through regulated channels that include clinical screening and oversight consistent with applicable laws. Patients should confirm eligibility and state-specific requirements, and ensure that any service provides licensed clinician review and uses certified pharmacies for dispensing.
Regardless of pathway, U.S. consumers should avoid unverified websites, international sources that bypass U.S. safeguards, or any vendor that offers promethazine without appropriate clinical review. Responsible, lawful access protects patient safety and ensures that promethazine is used effectively for allergy relief, nausea, and motion sickness with appropriate risk management.
Phenergan is the brand name for promethazine, a first-generation antihistamine with antiemetic (nausea-preventing), anticholinergic, and sedative properties. It’s used for allergies (rhinitis, hives), motion sickness, nausea and vomiting, pre- and post-operative sedation, and short-term nighttime sedation when appropriate.
Promethazine blocks H1 histamine receptors in the brain and peripheral tissues, reducing allergy symptoms. It also dampens signals in the vomiting center and vestibular system (motion balance), which helps prevent nausea and motion sickness. Its anticholinergic effects add to drying and sedative actions.
It is available as tablets, oral syrup, rectal suppositories, and injections (the latter administered by healthcare professionals only due to risk of tissue injury if misused).
Taken by mouth, it usually starts working within 20–60 minutes. Effects often last 4–12 hours, sometimes longer, especially the sedative effects.
Drowsiness, dizziness, dry mouth, blurred vision, constipation, and difficulty urinating are common due to anticholinergic effects. Some people also experience headache, coordination issues, or photosensitivity.
Seek medical help for severe sleepiness or unresponsiveness, confusion, agitation, hallucinations, irregular heartbeat, seizures, trouble breathing, jaundice, or signs of allergic reaction (rash, swelling, wheezing). Injection forms carry a risk of severe tissue damage if they leak outside the vein.
Do not use in children under 2 years due to risk of fatal respiratory depression. Avoid if you have a known allergy to promethazine or other phenothiazines, are in a comatose state, or currently have lower respiratory symptoms (e.g., acute asthma exacerbation). Use with caution in older adults, those with glaucoma, urinary retention/BPH, severe liver disease, sleep apnea, or seizure disorders.
No. It is not an opioid or benzodiazepine and is not considered addictive. However, misuse for sedation is unsafe.
It can cause drowsiness and is sometimes used short term for nighttime sedation, but it is not a first-line insomnia treatment due to daytime hangover and anticholinergic side effects. Non-drug measures or safer sleep medications may be preferred.
Yes. It helps prevent and treat motion sickness by acting on the vestibular system. For prevention, a dose is typically taken 30–60 minutes before travel and may be repeated as directed by your clinician.
Typical adult oral doses vary by indication: allergies 12.5–25 mg up to 3–4 times daily (often 25 mg at bedtime), motion sickness 25 mg before travel, nausea 12.5–25 mg every 4–6 hours as needed, and pre-sedation 25–50 mg at bedtime. Always follow your prescriber’s instructions.
It is contraindicated in children under 2 years. In older children, dosing is weight-based and must be prescribed by a clinician due to the risk of respiratory depression and other side effects.
Avoid driving, operating machinery, or tasks requiring alertness until you know how it affects you. It commonly causes drowsiness and can impair reaction time.
It may reduce runny nose and sneezing and is sometimes combined with codeine for cough, but combination products are not recommended for many people and can be risky. Simple measures and non-sedating options are often preferred.
Avoid combining with alcohol, opioids, benzodiazepines, sleep aids, or other sedating antihistamines. Use caution with anticholinergics (e.g., some bladder meds), MAO inhibitors, and drugs that may prolong QT. Always review your medication list with your healthcare provider.
No. Alcohol amplifies promethazine’s sedative and respiratory-depressant effects, increasing risks of dangerous drowsiness, impaired coordination, and breathing problems. Allow alcohol to clear fully before considering Phenergan, and ask your clinician for safer alternatives.
Promethazine has been used in pregnancy, particularly for nausea and vomiting when other options fail, but it should be used only if the potential benefit justifies the risk. Many clinicians prefer doxylamine/pyridoxine first-line for morning sickness. Discuss with your obstetric provider before use.
Promethazine may pass into breast milk and could cause infant drowsiness, irritability, or feeding difficulties. It may also reduce milk supply in early postpartum. Safer non-sedating antihistamines are often preferred. Consult your pediatrician and lactation specialist.
Tell your surgeon and anesthetist if you use Phenergan. It is sometimes used preoperatively for nausea or sedation, but combining with anesthesia, opioids, or benzodiazepines increases sedation and breathing risks. Your team will advise if and when to stop.
Caution is needed. Promethazine can thicken airway secretions and depress respiration, especially when combined with other sedatives. People with severe asthma exacerbations or untreated sleep apnea should avoid it unless specifically directed by a clinician.
Use caution. Its anticholinergic effects can precipitate angle-closure glaucoma and worsen urinary retention in men with BPH. Seek medical advice before use if you have these conditions.
Promethazine is metabolized in the liver. Reduced doses or alternative therapies may be needed if you have significant hepatic impairment. Discuss with your clinician, and avoid alcohol and other sedatives.
Use caution. Many antidepressants and anxiolytics cause sedation; combined use can impair alertness. MAO inhibitors are a particular concern and may intensify anticholinergic and CNS-depressant effects. Always consult your prescriber before combining.
Both are first-generation antihistamines and effective for allergy symptoms, but both are sedating. Benadryl is commonly used for acute allergic reactions; Phenergan adds stronger antiemetic and anticholinergic effects and often more sedation. For daily allergies, non-sedating second-generation antihistamines are generally preferred.
Both help, but promethazine is often considered slightly more potent for motion sickness and nausea, with a higher likelihood of drowsiness. Dimenhydrinate may be better tolerated for daytime use due to somewhat less sedation in many people.
Meclizine is effective for motion sickness and vertigo (e.g., vestibular neuritis, BPPV adjunct) and tends to be less sedating than promethazine. Phenergan may be more potent for nausea but is more likely to impair alertness. Choose based on how much sedation you can tolerate.
Both are sedating first-generation antihistamines. Hydroxyzine is commonly chosen for itching and short-term anxiety because of established dosing in those conditions. Phenergan has stronger antiemetic effects. Either can cause drowsiness and anticholinergic effects; selection depends on the primary symptom.
Doxylamine, especially when combined with vitamin B6 (pyridoxine), is first-line for pregnancy-related nausea. Promethazine is a second-line option when first-line therapy is inadequate. Doxylamine typically has a more favorable pregnancy safety profile.
Chlorpheniramine is less sedating than promethazine and can be more suitable for daytime allergy control, though it still causes drowsiness in some. Phenergan is usually not ideal for daytime allergies due to sedation and anticholinergic effects.
Both are used for seasickness. Cyclizine is often preferred for daytime or longer trips due to less sedation for many users, while promethazine may be chosen when stronger anti-nausea action is needed and sedation is acceptable.
Neither should be used in children under 2 years. In older children, dimenhydrinate or meclizine is often preferred because of a longer pediatric track record and potentially fewer respiratory risks. Pediatric dosing must be guided by a clinician.
Both are phenothiazine derivatives used for nausea. Prochlorperazine primarily blocks dopamine receptors and is often chosen for migraine-related nausea; it may cause extrapyramidal side effects. Promethazine is an antihistamine with strong sedative and anticholinergic effects. The choice depends on the cause of nausea, side-effect profile, and clinician preference.
Cetirizine is a second-generation antihistamine that is effective for allergies with far less sedation than promethazine. Phenergan is rarely recommended for routine seasonal allergy control due to sedation and anticholinergic effects.
Loratadine is minimally sedating and preferred for daytime allergy relief. Promethazine is markedly sedating and more appropriate when sedation is acceptable or when nausea control is needed.
Fexofenadine is non-sedating and effective for hay fever with a favorable safety profile. Promethazine treats allergic symptoms but with significant sedation and anticholinergic burden, so it is not first-line for hay fever.
Both can induce sleep, but neither is ideal for chronic insomnia. Doxylamine is commonly marketed as an OTC sleep aid and may have a more predictable sleep effect. Promethazine often causes stronger morning grogginess and anticholinergic side effects.
For older adults, both carry Beers Criteria cautions due to anticholinergic burden and fall risk. If an antihistamine is necessary, meclizine may be somewhat better tolerated than promethazine, but non-anticholinergic alternatives should be considered first.
In acute allergic reactions (non-anaphylaxis), both can help; diphenhydramine is often used due to familiarity and availability. Neither replaces epinephrine for anaphylaxis. Promethazine is more sedating and may worsen hypotension in severe reactions, so clinical judgment is needed.
