Phenylephrine
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Phenylephrine: From Allergic Rhinitis and Nasal Congestion to Nasal Cavity Disease
One-Sentence Summary
Phenylephrine is an alpha-1 adrenergic agonist originally used as a decongestant for allergic rhinitis, the common cold, pharyngitis and conjunctivitis, and in other conditions such as haemorrhoids. The TxGNN model predicts it may be effective for nasal cavity disease. The evidence is limited: no registered clinical trials were found for this indication, and the 5 publications retrieved are mostly reviews, clinical reports and combination-product studies.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Allergic rhinitis, vasomotor rhinitis, pharyngitis, common cold, conjunctivitis (atopic, papillary, vernal), nasopharyngitis, headache disorder, haemorrhoid, proctitis (from the knowledge graph; Singapore licence indication text is not available) |
| Predicted New Indication | Nasal cavity disease |
| TxGNN Prediction Score | 99.97% |
| Evidence Level | L4 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 19 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism-of-action data are not available in the data compiled for this report. Based on known pharmacology, phenylephrine is a selective alpha-1 adrenergic agonist. It constricts blood vessels in the mucosa, which reduces swelling and congestion.
The predicted indication is largely an extension of its existing nasal uses (rhinitis, nasopharyngitis, common cold). Nasal mucosal decongestion is also used topically in nasal surgery to reduce bleeding, so biological plausibility is high. However, "nasal cavity disease" is a broad category, and the prediction does not specify which condition would benefit.
Clinical Trial Evidence
Currently no related clinical trials registered for nasal cavity disease.
(For reference, the lower-ranked prediction "bronchial disease" has one completed Phase 2 trial, NCT00373802, a randomized, double-blind, placebo-controlled study of nasal phenylephrine in 50 infants with bronchiolitis. Results were not provided.)
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 40899890 | 2025 | Experimental and clinical evaluation | Vestnik Otorinolaringologii | Safety and efficacy of Polydexa spray (dexamethasone, neomycin, polymyxin B and phenylephrine) in acute rhinosinusitis; evidence is for the combination, not phenylephrine alone |
| 37184554 | 2023 | Clinical article | Vestnik Otorinolaringologii | Endoscopic state of the nasal mucosa after topical anti-inflammatory and antibacterial therapy, including Polydexa with phenylephrine |
| 37970776 | 2023 | Review | Vestnik Otorinolaringologii | Pathogenesis-based treatment of inflammatory diseases of the nose and paranasal sinuses |
| 25133491 | 2014 | Randomized clinical trial | PLoS One | Topical tranexamic acid and bleeding during endoscopic sinus surgery; phenylephrine is not the focus |
| 7378007 | 1980 | Case report | Archives of Ophthalmology | Toxic reactions after intranasal cocaine, with an additional reaction to intranasal phenylephrine |
Singapore Market Information
There are 19 valid single-ingredient licences. The approved indication text is not available for any of them. Five main authorizations:
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN10139P | Minims Phenylephrine Hydrochloride Eye Drops 2.5% w/v | Solution | Not available |
| SIN04319P | Minims Phenylephrine Hydrochloride Eye Drops 10% w/v | Solution | Not available |
| SIN15896P | Phenylalpha Solution for Injection 50mcg/ml | Injection, solution | Not available |
| SIN13878P | Panadol Cold Relief PE Caplet | Tablet | Not available |
| SIN12603P | Decolgen Non Drowse Caplets | Tablet | Not available |
Other licences cover eye drops, injection, nasal/throat spray, tablets, capsules and powder for cold and flu products.
Safety Considerations
- Contraindications flagged in the knowledge graph (not label text): hypertension, liver failure and liver disease, epilepsy, insomnia, COPD, gastric and peptic ulcer, porphyria, kidney disease, pancreatitis, gallbladder disease, thrombocytopenia, adrenocortical insufficiency, hypothyroidism, inflammatory bowel disease, psychotic and other mental disorders, and others.
- Drug interactions (100 found; moderate-level examples): antidiabetic drugs (acarbose, glimepiride, glipizide, glyburide, canagliflozin, dapagliflozin, empagliflozin, exenatide, human insulin), anticholinergics (atropine ophthalmic, hyoscyamine, clidinium) and diethylpropion.
- Literature signals: a vasoconstrictor may raise blood pressure, and frequent use of vasoconstrictor drops may cause rebound hyperaemia. Intranasal use together with cocaine or other sympathomimetics has caused toxic reactions.
Please also refer to the package insert for warnings and contraindications, which were not available in the data compiled for this report.
Conclusion and Next Steps
Decision: Hold
Rationale: The mechanism is plausible and the drug is widely marketed in Singapore, but there are no registered trials for nasal cavity disease. The retrieved literature is largely about combination products, reviews or unrelated topics, so evidence is at L4. Other predictions in the list (for example acute laryngopharyngitis, faucial diphtheria, cervical disc disorder) have no supporting evidence at all. The trigeminal autonomic cephalalgia literature is diagnostic pupillometry, not therapeutic.
To proceed, the following is needed:
- Package insert warnings and contraindications from the HSA
- Detailed mechanism of action data (MOA)
- Definition of a specific nasal condition (for example acute rhinosinusitis) and controlled trials of phenylephrine alone against placebo or standard care
- Safety review for patients with hypertension, cardiovascular disease and diabetes, and for paediatric use
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.