What are the major indications for Phenergan?

October 13, 2025 •

4 min read

Promethazine, sold under the brand name Phenergan, is a first-generation antihistamine developed in France in 1946 [1.2.4]. This article explores the question: What are the major indications for Phenergan?, detailing its diverse uses from managing allergies to preventing post-operative nausea [1.2.2].

Quick Summary

Phenergan (promethazine) is an FDA-approved prescription medication primarily used to treat allergic conditions, nausea, vomiting, and motion sickness, and for sedation [1.2.1, 1.2.2]. Its versatile effects stem from its action as a potent antihistamine and its ability to block other brain chemicals [1.3.2].

Key Points

Four Main Uses: Phenergan is FDA-approved for allergic conditions, nausea and vomiting, motion sickness, and sedation [1.2.2].
Black Box Warning: It is contraindicated in children under 2 years old due to the risk of fatal respiratory depression [1.4.2].
Potent Sedation: One of its most common and significant side effects is marked drowsiness, which can impair driving and other hazardous tasks [1.11.2].
Antihistamine Action: For allergies, it works by blocking histamine (H1) receptors, relieving symptoms like runny nose, sneezing, and hives [1.2.3].
Antiemetic Effect: It controls nausea and vomiting by acting on dopamine and acetylcholine receptors in the brain's chemoreceptor trigger zone [1.3.2].
Pre-Surgical Use: It is often used before and after surgery to relieve anxiety, produce light sleep, and prevent nausea [1.2.1].
Multiple Forms: Phenergan is available as tablets, syrup, rectal suppositories, and an injectable solution to suit different clinical needs [1.2.3, 1.6.2].

Introduction to Phenergan (Promethazine)

Promethazine, widely known by its brand name Phenergan, is a phenothiazine derivative and a first-generation antihistamine [1.2.2, 1.5.1]. Its discovery dates back to the 1940s, and it was approved by the FDA before March 1951 [1.2.4]. Unlike newer antihistamines that are more selective, Phenergan affects a variety of receptors in the brain, including histamine, dopamine, and acetylcholine receptors [1.3.2, 1.6.1]. This broad mechanism of action gives it a unique and versatile range of therapeutic effects, but also contributes to its significant side effect profile, most notably sedation [1.3.2, 1.2.2]. It is available in several forms, including oral tablets, syrup, rectal suppositories, and as an injection administered by a healthcare provider [1.2.3, 1.5.4].

What are the Major Approved Indications for Phenergan?

The U.S. Food and Drug Administration (FDA) has approved Phenergan for several distinct medical purposes [1.2.2].

Allergic Conditions

As a potent H1-receptor blocker, Phenergan is effective at treating various allergic conditions [1.2.2]. It works by preventing histamine, a substance the body releases during an allergic reaction, from binding to its receptors [1.2.3]. This helps relieve symptoms such as:

Seasonal and perennial allergic rhinitis (hay fever) [1.2.1]
Vasomotor rhinitis [1.2.1]
Allergic conjunctivitis (itchy, watery eyes from allergens) [1.2.1]
Mild, uncomplicated skin allergies like urticaria (hives) and angioedema [1.2.1]
Dermographism (a type of hives caused by pressure on the skin) [1.2.1] It is also used as an adjunctive therapy for severe allergic reactions (anaphylaxis) after epinephrine has been administered [1.2.2].

Nausea and Vomiting (Antiemetic)

Phenergan has substantial antiemetic properties, making it effective for the prevention and control of nausea and vomiting [1.2.2]. It is particularly useful for nausea and vomiting associated with certain types of anesthesia and surgery [1.2.1]. Its effectiveness comes from its ability to block dopamine and acetylcholine receptors in the part of the brain that controls the vomiting reflex [1.3.2, 1.7.4].

Motion Sickness

For both active treatment and prevention (prophylaxis) of motion sickness, Phenergan is a well-established option [1.2.1]. To be most effective, it should be taken 30 to 60 minutes before travel is expected to begin [1.2.2, 1.6.4]. The typical adult dose is 25 mg, which can be repeated 8 to 12 hours later if needed [1.6.2].

Sedation

Due to its strong central nervous system depressant effects, Phenergan is used to induce sedation in several clinical settings [1.6.2]. Its approved uses for sedation include:

Preoperative and postoperative sedation: It helps relieve apprehension and produces a light sleep from which the patient can be easily aroused [1.2.1, 1.6.2].
Obstetric sedation: Used during labor [1.2.1].
Adjunctive therapy for pain: It is used alongside analgesics like meperidine to enhance their pain-relieving and sedative effects after surgery [1.2.1].

Critical Safety Information and Side Effects

While effective, Phenergan carries significant risks. The most critical is an FDA Black Box Warning regarding its use in pediatric patients. Phenergan is contraindicated in children under 2 years of age due to the risk of potentially fatal respiratory depression [1.4.2, 1.4.3]. Caution is advised for children 2 years of age and older, and it should be used at the lowest effective dose [1.4.2].

Common side effects are often related to its sedative and anticholinergic properties and include [1.5.1, 1.5.3]:

Marked drowsiness and dizziness
Dry mouth
Confusion
Blurred vision
Disorientation

Because of its profound sedative effects, patients should not drive or operate heavy machinery until they know how the medication affects them [1.11.2]. The impairment can be amplified by alcohol or other CNS depressants [1.11.2].

Comparison with Other Common Medications

To understand Phenergan's role, it's helpful to compare it to other drugs used for similar indications.


Feature	Phenergan (Promethazine)	Benadryl (Diphenhydramine)	Zofran (Ondansetron)
Drug Class	First-Generation Antihistamine, Phenothiazine [1.2.2]	First-Generation Antihistamine	Serotonin 5-HT3 Receptor Antagonist [1.7.1]
Primary Mechanism	Blocks histamine (H1), dopamine, and acetylcholine receptors [1.3.2].	Blocks histamine (H1) and acetylcholine receptors.	Selectively blocks serotonin receptors in the brain and gut [1.7.1].
Primary Uses	Allergies, nausea/vomiting, motion sickness, sedation [1.2.1].	Allergies, hives, cold symptoms, sleep aid.	Nausea/vomiting from chemotherapy, radiation, or surgery [1.7.1].
Key Side Effects	Strong sedation, dizziness, dry mouth, confusion, risk of respiratory depression [1.5.3].	Sedation (less potent than Phenergan), dry mouth, dizziness.	Headache, constipation, diarrhea, fatigue. Less sedating than Phenergan [1.7.1, 1.7.2].
Pediatric Use	Contraindicated under age 2 [1.4.2].	Generally used in children over 2, with caution.	Can be used in children as young as 4 years old (or 1 month for IV) [1.7.1, 1.7.2].

Conclusion

In summary of 'What are the major indications for Phenergan?', it is clear that promethazine is a multifaceted medication with well-defined roles in managing allergies, nausea, motion sickness, and providing sedation [1.2.1, 1.2.2]. Its powerful and wide-ranging mechanism of action makes it highly effective, but this same characteristic is responsible for its significant side effect profile, particularly drowsiness and the serious risk of respiratory depression in young children [1.4.2, 1.5.3]. Therefore, its use must be carefully weighed by a healthcare professional, especially when other medications are being taken or in vulnerable populations like children and the elderly [1.5.1].

For more detailed information, consult the official FDA documentation for Phenergan: https://www.accessdata.fda.gov/drugsatfda_docs/label/2004/07935s030lbl.pdf [1.2.1]

Frequently Asked Questions

No, you should not drive or operate machinery after taking Phenergan until you know how it affects you. It can cause marked drowsiness, dizziness, and impair mental and physical abilities [1.11.2, 1.11.3].

Phenergan typically starts to work within 20 minutes of oral administration. Its effects can last from 4 to 6 hours, and may persist for up to 12 hours in some individuals [1.9.1, 1.9.4].

Phenergan has a black box warning from the FDA and is contraindicated in children under two because it can cause severe, potentially fatal respiratory depression (slowing or stopping of breathing) [1.4.2, 1.4.3].

No, Phenergan (promethazine) itself is not an opioid or a narcotic [1.6.1]. It is an antihistamine. However, it is sometimes combined with the opioid codeine in cough syrups, and that combination product does contain a narcotic [1.10.3].

Yes, promethazine is sometimes used to relieve symptoms of the common cold, such as sneezing and runny nose [1.12.1]. It may also be found in combination products with decongestants [1.12.4].

While promethazine itself is not classified as a controlled substance and is considered to have a low potential for addiction when used as directed, it can be misused for its sedative effects, especially in combination with other substances like opioids [1.10.3, 1.6.1]. This misuse can lead to dependence [1.10.2].

While not FDA-approved for treating general anxiety, Phenergan is approved for sedation and to relieve apprehension before surgery or during labor [1.2.1, 1.8.2]. It is sometimes used off-label for its sedative effects in hospital settings to manage agitation [1.8.2].