Tetrahydrozoline (tetryzoline)

Tetrahydrozoline is used in eye drops that relieve minor eye irritation.

Pronunciation: tet-rah-high-DROZ-ah-leen

What are tetrahydrozoline’s uses?

Tetrahydrozoline is a decongestant that helps treat minor eye ailments caused by, for example, a cold, hay fever, or an allergy. It constricts swollen blood vessels in the eye caused by irritants, thus reducing redness.

What dosage should you take?

Adults can generally apply one or two drops in the eyes’ conjunctival sac(s) three or four times a day as needed. However, first check the correct dosage with your Clicks pharmacist.

What special precautions should you take?

  • Consult your doctor if you haven’t seen any improvement in symptoms after three days, or if they worsen.
  • Always wash your hands before and after using the eye drops.
  • Apply by tilting your head back, using your index fingers to pull your lower eyelid out to form a pocket, which you then squeeze the medicine into. Close your eyes and apply light pressure with your finger to the inside corner of your eye for about two minutes.
  • If the medicine looks cloudy and changes colour, do not use them.
  • During pregnancy or breastfeeding, ensure you speak to your doctor or Clicks pharmacist about its safety before using it.
  • These eye drops may cause blurred vision, so avoid driving or any other potentially dangerous activities such as operating heavy machinery, until you can see clearly again.
  • If you wear soft contact lenses, discuss the best way to apply the eye drops with your Clicks pharmacist.

Tetrahydrozoline eye drops should be used with caution if you suffer from the following conditions, so inform your doctor or Clicks pharmacist before using them:

Rather avoid usage if you suffer from porphyria (a group of rare genetic disorders that affect mainly the skin or nervous system).

What drug interactions could you experience?

As a rule, always inform your doctor or Clicks pharmacist what prescription and non-prescription medications, vitamins, nutritional supplements and herbal products you are taking or planning to take to ensure you don’t suffer the effects of adverse drug interactions.

What are tetrahydrozoline’s side effects?

Common side effects could include:

  • Blurred vision
  • Stinging
  • Eye pain
  • Persistent eye irritation
  • Dilated pupils

This is not a complete list of side effects. It’s essential that you call your doctor should you notice any severe or odd side effects.

What are the overdose symptoms?

Call a doctor or the ambulance immediately if you suspect an overdose and notice adverse symptoms which could include:

  • Pounding heartbeat
  • Dizziness
  • Nausea
  • Headache
  • Mood changes
  • Trouble sleeping
  • Tremors
  • Profuse sweating
  • A severe allergic reaction such as hives, itching, rash, trouble breathing
The accuracy of this information was checked and approved by Clicks' pharmacist Waheed Abdurahman in August 2015