Tetryzoline: imidazoline sympathomimetic in eye and nose drops
Tetryzoline (synonym tetrahydrozoline) is a topical alpha sympathomimetic from the imidazoline group. In Germany the substance is found mainly in eye drops such as Berberil N and Visine, as well as in some decongestant nasal drops. The best-known use is the symptomatic treatment of eye redness from non-specific irritation. In the USA tetryzoline is more often a component of OTC eye drops such as Visine and Murine.
Through selective vasoconstriction of conjunctival vessels, red eyes quickly turn white again. The symptomatic effect makes tetryzoline a popular cosmetic option, but with risks: chronic use can lead to reactive hyperaemia (rebound).
Mechanism of action
Tetryzoline is a direct agonist at alpha 1 and alpha 2 adrenoceptors. On vascular smooth muscle of conjunctival and nasal microcirculation, activation produces vasoconstriction. The result is less reddened eyes and clearer nose.
Use is strictly topical; systemic absorption is low but can become clinically relevant with frequent or large-area application or accidental ingestion. With oral intake, central nervous effects can occur, especially in children who accidentally access eye drop bottles.
Indications
- Eye redness from non-specific irritation: dust, wind, fatigue, cosmetic use
- Seasonal allergic conjunctivitis: as symptomatic relief of redness, complementing antihistaminic eye drops
- Acute rhinitis: as decongestant nasal medication in colds and sinusitis
- Eye examinations: rarely as vasoconstrictor for better assessment of the anterior segment
Dosing and administration
Eye drops 0.05 %: 1 drop two to three times daily into the conjunctival sac, no longer than 5 to 7 days continuously.
Nose drops 0.05 % (or age-appropriate concentrations): 1 to 2 drops or sprays one to three times daily in each nostril, no longer than 5 to 7 days.
Use is mainly for acute symptomatic relief. With longer use, a privinism-like reaction with rebound conjunctival redness or nasal mucosal swelling can occur after the effect wears off.
Use in contact lens wearers is possible; some preservatives can accumulate in soft lenses. Remove lenses, reinsert at the earliest 15 minutes after use.
Side effects
Common: burning or stinging immediately after instillation, mydriasis (especially in children), reactive hyperaemia after chronic use.
Uncommon: tachycardia, hypertension (with systemic absorption), dry mouth, nausea, headache.
Rare: with accidental ingestion, especially in children, CNS depression, bradycardia, hypothermia, respiratory depression up to coma. These reactions are typical for imidazoline poisoning and represent paediatric emergencies.
Important points:
- With accidental oral intake by children, seek emergency care
- Prolonged use (over 7 days) leads to rebound reactions with intensified redness
- With chronically red eyes, the cause should be clarified rather than masking the symptom by vasoconstriction
Interactions
- MAO inhibitors and tricyclic antidepressants: theoretical risk of hypertensive reactions; clinically rarely relevant with topical use
- Other sympathomimetics: additive effects
- Antihypertensives: partial antagonism
- Other eye drops: apply with at least 5 minutes between drops
Special considerations
Pregnancy and breastfeeding: short-term topical use at low dose is acceptable; avoid prolonged or frequent use if possible.
Children: specific concentrations for infants and toddlers; tetryzoline should be used in very young children only under medical guidance. Store out of reach, since even small oral amounts can cause life-threatening reactions.
Narrow-angle glaucoma: tetryzoline eye drops can provoke an attack and are therefore contraindicated.
Hypertension, coronary heart disease, hyperthyroidism: caution with prolonged or frequent use.
Treatment duration: strict limitation to a few days is decisive to avoid rebound.
Diagnostic clarification: with chronic eye redness or mucosal swelling, the cause (allergy, infectious or inflammatory disease, dryness, mechanical irritation) should be clarified.
Related substances
- Xylometazolin, decongestant nasal drug
- Xylometazoline, English spelling
- Oxymetazolin, another imidazoline
- Azelastine hydrochloride, antihistaminic eye drops
- Tafluprost, glaucoma drug as ophthalmic alternative
Frequently asked questions
How quickly does tetryzoline work?
Vasoconstriction sets in within a few minutes; the eye or nose looks visibly less red or freer. Action lasts 4 to 8 hours.
Why not use longer than a week?
With longer use, the microcirculation gets used to vasoconstriction. On stopping, reflexive vessel widening occurs, manifesting as rebound redness or mucosal swelling. The phenomenon is colloquially called privinism. Limiting therapy to maximum 5 to 7 days reduces this risk.
What if a child swallows it?
Contact a poison control centre or emergency department immediately. As little as 1 to 2 ml can cause severe CNS symptoms in toddlers. Rapid medical care is decisive. Always store eye drops child-safe.
Do tetryzoline eye drops help with allergies?
They reduce redness but do not treat the underlying allergic reaction. For allergic conjunctivitis, antihistaminic and mast-cell stabilising eye drops such as azelastine, olopatadine or cromoglicate are first-line. Tetryzoline can be used short-term as an adjunct.
Sources
- BfArM Federal Institute for Drugs and Medical Devices
- EMA European Medicines Agency
- BVL Federal Office of Consumer Protection
- Gelbe Liste tetryzoline monograph
Legal notice and disclaimer
The information on this page is provided for general information purposes only and does not constitute medical advice, diagnosis or treatment recommendation. It does not replace the advice of a licensed physician or pharmacist. Medicines should only be used after a doctor's prescription or pharmacy supply. All information is based on summaries of product characteristics and accepted scientific sources at the time of writing; the current SmPC of the manufacturer is always decisive. Sanoliste accepts no liability for completeness, timeliness or accuracy. In a medical emergency, dial the emergency number 112.