What Zaditor is
Zaditor is the brand name for ketotifen fumarate 0.025% eye drops, made by Alcon. Like olopatadine, ketotifen is a "dual-action" drop. It blocks histamine at H1 receptors, and it steadies the mast cells that release histamine in the first place PMID: 30020258.
The item we link to is a twin pack of two 5 mL bottles. The dose is one drop in each affected eye every 8 to 12 hours, no more than twice a day.
How well it works
Antihistamine and mast-cell-stabilizer eye drops are among the best-supported allergy treatments sold without a prescription. A Cochrane review of 30 trials found that all the drops it studied, ketotifen included, reduced symptoms of seasonal allergic conjunctivitis compared with placebo in the short term PMID: 26028608.
Ketotifen has two strong trials of its own:
- In an allergen-challenge study, ketotifen reduced itching and redness better than placebo at every time point. It worked when given 15 minutes before exposure and still worked 8 hours later PMID: 12742839.
- In a 519-person pollen-season trial, more people responded to ketotifen twice daily than to placebo. Ketotifen also beat levocabastine, an older antihistamine drop PMID: 14507747.
What it treats well: itchy, watery, red eyes caused by pollen, dust mites or pet dander. It's handy for flare-ups, like before visiting a friend with a cat.
What it doesn't treat: dry eye, eye infections, or redness from irritation. If your eyes are red but not itchy, allergy may not be the cause.
Side effects and safety
Ketotifen drops are generally well tolerated. In the large pollen-season trial, side effects were similar across ketotifen, placebo and the comparison drop PMID: 14507747. Brief stinging on the first drop is common with most eye drops.
Practical tips from the label:
- Remove contact lenses before using the drops. Wait at least 10 minutes before putting them back in.
- Don't touch the dropper tip to your eye or anything else.
- Stick to twice a day at most.
- See a clinician if you have eye pain, vision changes, or symptoms that get worse or don't improve.
Don't swap in "get the red out" drops. Decongestant drops such as tetrahydrozoline or naphazoline hide redness without treating the allergy. With continued use, some can lose effect and cause rebound redness PMID: 32801982.
Zaditor vs. Pataday
Pataday (olopatadine 0.2%) is the main alternative. Both work. Here's how they differ:
- Redness: a meta-analysis of seven randomized trials found olopatadine led to significantly less redness than ketotifen. It found no significant difference in itching, tearing or papillae PMID: 37312902.
- Speed: one randomized trial found olopatadine 0.1% relieved symptoms faster than ketotifen by day four, with fewer side effects PMID: 29719638.
- Dosing: Zaditor is up to twice a day. Pataday is once a day.
- Price: Zaditor usually costs less.
So ketotifen isn't a downgrade. It's a slightly less convenient version of a similar drug, usually at a lower price.
Who should buy it
Buy Zaditor if you want an effective allergy eye drop on a budget, use drops only during occasional flare-ups, or are treating a child 3 or older.
Buy Pataday instead if you'd rather use one drop a day, or if redness bothers you most.
Add an allergy pill like Zyrtec if sneezing and a runny nose come with the itchy eyes, or Flonase if congestion is the main problem. See our full Best Eye Drops for Allergies ranking for more.