Use of Avil (Diphenhydramine) for Viral Rhinorrhea
Avil (diphenhydramine), a first-generation antihistamine, is NOT recommended for reducing rhinorrhea in viral upper respiratory infections, as antihistamines have not been shown to effectively reduce rhinorrhea in viral rhinitis and carry significant sedation risks that outweigh any potential benefits. 1, 2
Why Antihistamines Are Ineffective for Viral Rhinorrhea
Evidence from Viral Rhinitis Studies
The European Position Paper on Rhinosinusitis (2020) evaluated antihistamines in post-viral acute rhinosinusitis and found that loratadine did not reduce rhinorrhea symptoms (MD=−0.06; 95% CI=−0.37-0.25, p=0.71) when added to standard treatment. 1
The American Academy of Otolaryngology-Head and Neck Surgery states that newer generation non-sedating antihistamines are relatively ineffective in treating common cold symptoms, and evidence for antihistamine efficacy specifically in viral rhinitis is limited. 2
Antihistamines work by blocking histamine receptors, but viral rhinorrhea is not primarily histamine-mediated—it results from the host inflammatory response to viral infection rather than allergic mechanisms. 2
The Problem with First-Generation Antihistamines Like Avil
Diphenhydramine causes significant sedation and impairment, with somnolence occurring in 22.1% of patients compared to 4.5% with second-generation antihistamines and 3.4% with placebo. 3
Guidelines explicitly recommend that if a first-generation antihistamine is prescribed, physicians must ensure patients understand the potential for adverse effects and the availability of alternative antihistamines with lower likelihood of adverse effects. 1
First-generation antihistamines like diphenhydramine produce sedation, impairment, and worsen sleep architecture, making them inappropriate choices even when antihistamines might be considered. 4
What Actually Works for Viral Rhinorrhea
First-Line Recommended Treatments
Intranasal anticholinergics are the evidence-based choice for rhinorrhea:
- Ipratropium bromide nasal spray effectively reduces rhinorrhea but has no effect on other nasal symptoms, with minimal side effects (possible nasal membrane dryness). 1
Nasal saline irrigation:
- Topical saline is beneficial in treating chronic rhinorrhea symptoms when used alone or as adjunctive treatment. 1
- Helps relieve congestion and facilitates clearance of nasal secretions. 2
Analgesics/antipyretics:
- Acetaminophen or ibuprofen for pain relief and fever control are appropriate symptomatic measures. 2
Short-Term Adjunctive Options
Topical nasal decongestants:
Oral decongestants:
- Can provide symptomatic relief but should be used with caution in patients with hypertension, cardiac arrhythmia, angina, cerebrovascular disease, bladder neck obstruction, glaucoma, or hyperthyroidism. 1
Critical Pitfalls to Avoid
Do not prescribe antibiotics for viral rhinitis—they are completely ineffective for viral illness and do not provide symptom relief. 2
Do not use antihistamines expecting rhinorrhea reduction in viral infections—the evidence shows they don't work for this indication. 1
Avoid first-generation antihistamines like diphenhydramine due to sedation, impairment, and lack of efficacy in viral rhinitis. 4, 3
Never extend topical decongestant use beyond 3-5 days—this causes rebound congestion that worsens the underlying problem. 2, 5
When Antihistamines Might Have a Role
The only scenario where antihistamines show any benefit in upper respiratory infections is with first-generation antihistamine/decongestant combinations (containing sustained-release pseudoephedrine and brompheniramine) for reducing cough and other symptoms—but this is for overall symptom relief, not specifically for rhinorrhea reduction. 2
However, given the sedation profile of first-generation antihistamines and the availability of more effective, targeted treatments for rhinorrhea (ipratropium bromide), this combination approach is not preferred. 1, 4