Indications
Tetrahydrozoline (also spelled Tetryzoline) is an eye decongestant. It is used for short-term relief of red, irritated eyes caused by minor irritants such as dust, smoke, swimming pool water, wind or mild allergy. In some eye drops it is combined with other medicines, for example a mild steroid such as Fluorometholone or an antihistamine, to also calm inflammation or itching.
How It Works
Tetrahydrozoline is a sympathomimetic, which means it acts like adrenaline on small blood vessels. It narrows (constricts) the swollen blood vessels on the white of the eye, so redness and puffiness go down within a few minutes. It does not treat the cause of the irritation.
Dosage and Administration
Adults and children over 6 years: usually 1 to 2 drops in the affected eye up to 3 or 4 times a day, or as directed on the label or by your doctor. Do not use for more than 3 days without medical advice. For combination drops containing a steroid, use only as prescribed.
- Wash your hands, tilt your head back, pull down the lower lid and place the drop without touching the eye with the tip.
- Remove soft contact lenses before use and wait at least 15 minutes before putting them back.
- Do not share the bottle with others.
Interactions
Only small amounts reach the blood, but tell your doctor if you take MAO inhibitors (such as Selegiline), tricyclic antidepressants (such as Amitriptyline) or blood pressure medicines, as these can rarely interact. Wait at least 5 minutes between different eye drops.
Contraindications
Do not use if you are allergic to Tetrahydrozoline or any ingredient, if you have narrow-angle (closed-angle) glaucoma, or in children under 2 years. Drops that also contain a steroid should not be used in viral, fungal or untreated bacterial eye infections.
Side Effects
Brief stinging or burning, blurred vision, enlarged pupils and eye irritation can occur. Using it too often or for too long can cause rebound redness, where the eyes become redder when the drops wear off. Rarely, when absorbed, it may cause headache, fast heartbeat or raised blood pressure.
Get urgent medical help if you have eye pain, a sudden change in vision, redness that gets worse or lasts more than 72 hours, or signs of a serious allergic reaction such as swelling of the face or difficulty breathing.
Pregnancy and Lactation
Safety in pregnancy and breastfeeding is not well studied. Use only if your doctor or pharmacist agrees that it is needed, and for the shortest time.
Precautions and Warnings
Use with care if you have heart disease, high blood pressure, diabetes or an overactive thyroid. Stop and see a doctor if eye pain, vision changes or worsening redness occur. Long-term use of steroid-containing combinations can raise eye pressure or cause cataract, so these need medical follow-up. Discard the bottle as directed after opening.
Overdose
Swallowing the drops, especially by young children, can be dangerous and may cause drowsiness, slow breathing, slow heartbeat, low body temperature or coma. Seek emergency help at once if a child swallows any amount. Using too many drops in the eye mostly causes irritation and rebound redness.
Therapeutic Class
Ophthalmic decongestant (sympathomimetic, alpha-adrenergic agonist).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children. Keep the bottle tightly closed and use within the time stated on the pack after opening.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.