Decongestants

Decongestants are a class of medicines that relieve nasal or sinus congestion by reducing swelling and inflammation of the mucous membranes in the nasal passages, typically caused by conditions such as the common cold, allergies, sinusitis, or other upper respiratory tract infections. Decongestants do not cure the underlying cause of congestion, but they provide symptomatic relief by constricting dilated blood vessels in the nasal mucosa.

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Pharmacological Classification

• Therapeutic Class: Nasal decongestants (systemic and topical)

• Pharmacological Class: Sympathomimetic agents (adrenergic agonists)

• ATC Code: R01A (topical) and R01B (systemic)

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Types of Decongestants

Decongestants are classified based on the route of administration into topical (nasal spray or drops) and systemic (oral) formulations. Both act as adrenergic agonists, primarily stimulating alpha-adrenergic receptors, resulting in vasoconstriction.

Topical Decongestants

• Examples: Xylometazoline, Oxymetazoline, Naphazoline, Phenylephrine (nasal)

• Delivered directly into the nose, acting rapidly within minutes

• Duration of action varies: Oxymetazoline lasts longer (~12 hours), while phenylephrine is shorter (~4 hours)

Systemic (Oral) Decongestants

• Examples: Pseudoephedrine, Phenylephrine (oral)

• Slower onset compared to nasal sprays but offer longer-lasting relief

• Beneficial in multi-symptom formulations with antihistamines, analgesics, or antitussives

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Mechanism of Action

Decongestants stimulate alpha-1 adrenergic receptors in the smooth muscle of the blood vessels in the nasal mucosa. This leads to:

• Vasoconstriction, reducing blood flow to the swollen mucosa

• Decreased edema, restoring airflow through nasal passages

• Improved drainage of sinus secretions

Some systemic decongestants (e.g., pseudoephedrine) also have beta-adrenergic activity, contributing to mild bronchodilation or increased heart rate.

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Indications

Decongestants are used to relieve congestion and improve nasal airflow in:

• Common cold

• Seasonal allergic rhinitis (hay fever)

• Perennial allergic rhinitis

• Acute and chronic sinusitis

• Eustachian tube dysfunction

• Barotrauma prevention (flying or scuba diving)

• Otitis media with effusion (adjunctive treatment)

They are symptomatic agents only and should be used in combination with other therapies when addressing allergic or infectious causes.

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Dosage and Administration

Topical Nasal Sprays

• Xylometazoline 0.05–0.1%: 1–2 sprays per nostril every 8–12 hours (max twice daily)

• Oxymetazoline 0.05%: 1 spray per nostril every 10–12 hours

• Phenylephrine 0.25–0.5%: every 4 hours

Do not use for more than 5 to 7 consecutive days to avoid rebound congestion (rhinitis medicamentosa).

Oral Decongestants

• Pseudoephedrine: 60 mg every 4–6 hours or 120 mg sustained-release every 12 hours

• Phenylephrine: 10 mg every 4 hours

• Max daily dose: 240 mg pseudoephedrine or 60 mg phenylephrine

Pediatric dosing requires age-appropriate adjustments, and use in children under 6 is discouraged in many guidelines due to risk of adverse effects.

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Contraindications

Decongestants are contraindicated in:

• Severe hypertension or coronary artery disease

• Hyperthyroidism

• Narrow-angle glaucoma

• Concurrent use with monoamine oxidase inhibitors (MAOIs)

• Prostatic hypertrophy (due to urinary retention risk)

• Children under 6 years (depending on jurisdiction and formulation)

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Precautions

Decongestants should be used cautiously in individuals with:

• Controlled hypertension

• Diabetes mellitus

• Seizure disorders

• Psychiatric conditions (e.g., anxiety, insomnia)

• Renal impairment

Topical decongestants are safer in cardiovascular conditions due to less systemic absorption but still require monitoring with prolonged use.

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Adverse Effects

Topical Decongestants

• Local irritation (burning, dryness, stinging)

• Rebound congestion with prolonged use (rhinitis medicamentosa)

• Temporary sneezing, nasal dryness, or epistaxis

• Rare systemic effects (tachycardia, headache)

Systemic Decongestants

• Elevated blood pressure, palpitations, tachycardia

• Insomnia, nervousness, restlessness

• Urinary retention

• Nausea, headache

• Psychological symptoms (especially in high doses): anxiety, agitation

• In rare cases: hallucinations, seizures (especially in pediatric overdose)

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Drug Interactions

• Monoamine oxidase inhibitors (MAOIs): Can lead to hypertensive crisis

• Beta-blockers: May reduce efficacy of beta-blockers; increase blood pressure

• Tricyclic antidepressants: Additive sympathomimetic effects

• Antihypertensives (e.g., methyldopa, guanethidine): May blunt therapeutic effects

• CNS stimulants (e.g., methylphenidate): Additive stimulation

• Linezolid: Risk of serotonin syndrome or hypertensive effects

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Pregnancy and Lactation

Pregnancy

• Oral decongestants (particularly pseudoephedrine) have been linked to fetal gastroschisis in early pregnancy

• Topical agents (especially oxymetazoline) are preferred if short-term use is necessary

• Use only if benefits outweigh potential fetal risks

Lactation

• Decongestants may reduce milk supply

• Pseudoephedrine is excreted in small amounts in breast milk

• Occasional use of topical decongestants is generally considered safe

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Use in Pediatrics

• Risk of toxicity in infants and young children

• Topical and oral decongestants are not recommended for children under 6 years in many regulatory jurisdictions (e.g., UK MHRA, US FDA advisory)

• Pediatric formulations must be used with careful dose adjustments

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Decongestants vs. Antihistamines (Comparison)

Decongestants relieve nasal congestion by vasoconstriction, whereas antihistamines block histamine-mediated allergic responses such as sneezing, itching, and runny nose. Decongestants work rapidly on vascular swelling; antihistamines address the underlying allergic cause.

Decongestants provide quick, symptomatic relief for blocked nose, while antihistamines are more preventive and long-term symptom controllers for allergic rhinitis.

In allergic rhinitis, combined therapy (e.g., loratadine + pseudoephedrine) is often more effective than either alone.

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Examples of Common Combination Products

• Actifed: Triprolidine + pseudoephedrine

• Sudafed Plus: Pseudoephedrine + paracetamol

• Claritin-D: Loratadine + pseudoephedrine

• Benadryl Allergy Relief Plus Decongestant: Acrivastine + pseudoephedrine

• Telfast-D: Fexofenadine + pseudoephedrine

These combinations target both congestion and allergy symptoms in one preparation.

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Withdrawal and Misuse

Long-term use of nasal decongestants (especially sprays like xylometazoline) can result in rhinitis medicamentosa—a cycle of worsening nasal congestion due to rebound vasodilation. This may require withdrawal and transition to intranasal corticosteroids or saline rinses under medical guidance.

Decongestants, especially pseudoephedrine, have potential for abuse, including being used as precursors in illicit methamphetamine production. As such, their availability is restricted in some countries.

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Counseling Points

• Limit use of nasal sprays to no more than 5–7 days to avoid rebound effects

• Use oral decongestants in the morning or early afternoon to prevent insomnia

• Report symptoms of palpitations, dizziness, or urinary retention

• Do not combine multiple cold medications containing decongestants

• Avoid in children <6 years unless under strict medical supervision

• For allergy-related nasal symptoms, consider adding or switching to intranasal corticosteroids or oral antihistamines