Does promethazine contain codeine? The antihistamine promethazine does not inherently contain codeine, but the two medications are frequently combined into a single prescription product. This combination, typically formulated as a syrup, is effective for managing severe cough and related upper respiratory symptoms. The prescription-only product joins a non-narcotic antihistamine with a mild opioid cough suppressant.
Promethazine as a Standalone Drug
Promethazine, often recognized by the brand name Phenergan, is classified as a first-generation antihistamine and a phenothiazine derivative. In its standalone form, this medication functions primarily by blocking histamine H1 receptors in the body, which trigger allergic reactions. This action helps to relieve symptoms like sneezing, runny nose, and watery eyes associated with hay fever or other allergies.
The drug also possesses strong anticholinergic properties, which contribute to its effectiveness in treating other conditions. When prescribed alone, promethazine is used to prevent motion sickness, control nausea and vomiting, and provide mild sedation. In this pure form, the medication is not an opioid and contains no codeine.
The Specific Combination Formulations
The confusion about promethazine stems from a specific, prescription-only liquid formulation. This common product is officially known as Promethazine Hydrochloride and Codeine Phosphate oral solution. It is a dual-ingredient medicine created to offer more comprehensive symptom relief than either compound could provide alone.
A standard concentration for this combination syrup is 6.25 milligrams of promethazine and 10 milligrams of codeine phosphate per 5-milliliter dose. This formulation is prescribed for the temporary relief of cough and upper respiratory symptoms linked to the common cold or seasonal allergies. Because it contains an opioid, the product is subject to strict governmental controls and requires a valid prescription.
Therapeutic Roles of Codeine and Promethazine
Each component in the combination syrup plays a distinct and complementary role in treating respiratory illness. The codeine component functions as an antitussive, or cough suppressant, by acting directly on the cough reflex center in the brain’s medulla. As a mild opioid, codeine depresses this reflex, effectively reducing the frequency and intensity of coughing fits.
Promethazine contributes to the overall therapeutic effect through its antihistamine and sedative actions. Its antihistamine properties help by drying up nasal and bronchial secretions, which alleviates post-nasal drip and upper airway irritation. The sedative effect also helps patients rest, which is beneficial when recovering from a persistent cough.
Regulatory Controls and Safety Concerns
The inclusion of codeine means that the Promethazine with Codeine syrup is a federally controlled substance, classified as a Schedule V (CV) drug in the United States. This classification indicates that the medication has a lower potential for abuse compared to Schedule II or III opioids, but still carries a risk of dependence and misuse. Strict regulations govern how the medication is prescribed, dispensed, and refilled to mitigate these risks.
The most significant safety concern involves the potential for respiratory depression, which is a severe slowing or stopping of breathing. This risk is amplified because both promethazine and codeine are central nervous system depressants, and their effects are additive. The combination is dangerous for children, leading to contraindications in patients under 12 years of age due to reports of life-threatening respiratory events.
The metabolism of codeine is also a factor, as some individuals are “ultra-rapid metabolizers” due to genetic variations in the CYP2D6 enzyme. These individuals convert codeine into the more potent morphine quickly, increasing the risk of overdose and severe respiratory depression. Furthermore, consuming the combination syrup with other depressants, such as alcohol or benzodiazepines, can lead to profound sedation, coma, or death.