Understanding What Does Pataday Do to the Body?

October 9, 2025 •

3 min read

Pataday is the brand name for the active ingredient olopatadine, which was previously the number-one doctor-prescribed eye allergy itch reliever. Today, it is available over the counter and is widely used to treat ocular allergy symptoms. But beyond providing fast relief, what does Pataday do to the body and, specifically, the eyes?

Quick Summary

Pataday (olopatadine) works in the body by providing targeted relief from eye allergy symptoms. It acts as a dual-action medication, functioning as both an antihistamine and a mast cell stabilizer to block the chemical reactions that cause itchy and red eyes.

Key Points

Dual Mechanism of Action: Pataday's active ingredient, olopatadine, acts as both a potent antihistamine and a mast cell stabilizer to combat eye allergies at their source.
Antihistamine Action: It blocks H1 receptors in the eye, preventing histamine from triggering the allergic cascade that causes redness, swelling, and itching.
Mast Cell Stabilization: It prevents mast cells from releasing inflammatory chemicals, providing a preventative effect against recurring allergic symptoms.
Rapid and Localized Relief: Applied topically, Pataday delivers fast-acting relief directly to the eyes with minimal systemic absorption, reducing the risk of body-wide side effects like drowsiness.
Multiple Formulations: Pataday comes in different strengths (0.1%, 0.2%, and 0.7%) that provide varying durations of relief, from 8 to 24 hours, with a corresponding dosing frequency.
Generally Safe: Pataday is typically well-tolerated, with common side effects limited to mild and transient ocular issues like stinging or blurred vision.
Differentiation from Competitors: It may offer a faster onset of action and lower incidence of some side effects compared to other over-the-counter options like Zaditor.

Pataday's Pharmacological Action: The Dual-Benefit Approach

Pataday's effectiveness against eye allergies comes from its dual-action mechanism. The active ingredient, olopatadine, belongs to a class of drugs known as ophthalmic antihistamines and mast cell stabilizers. Instead of just masking symptoms, it addresses the core cause of allergic reactions in the eyes at a cellular level.

How Pataday Blocks Histamine

When your body encounters an allergen—like pollen, dust, or pet dander—it triggers an immune response. This response involves the release of a chemical called histamine from cells known as mast cells. This histamine is what causes the uncomfortable symptoms of allergic conjunctivitis, including redness, swelling, and severe itching.

Pataday is a selective histamine H1 receptor antagonist. This means it specifically targets and blocks the H1 receptors located on the surface of cells in the conjunctiva (the clear membrane covering the white of the eye). By blocking these receptors, Pataday prevents the histamine from binding to them, effectively stopping the allergic reaction from causing its symptomatic effects. Because it is applied directly to the eyes as a topical solution, it can start working within minutes.

How Pataday Stabilizes Mast Cells

Pataday's second mechanism of action is as a mast cell stabilizer. As mentioned, mast cells are the source of histamine and other inflammatory mediators that are released during an allergic reaction. Pataday helps to stabilize these mast cells, preventing them from releasing their inflammatory chemicals in the first place. This provides a preventative effect, reducing the likelihood and severity of allergic symptoms from recurring.

Systemic vs. Ocular Effects

Since Pataday is applied topically to the eyes, its effects are highly localized, and the risk of systemic (body-wide) side effects is very low. In clinical studies, systemic absorption after topical ocular administration has been found to be minimal. This targeted delivery is a major advantage over oral antihistamines, which circulate throughout the body and can cause side effects like drowsiness or dry mouth. Minimal systemic exposure means Pataday is a safer and more effective option for people whose primary allergy symptoms are eye-related.

Common Side Effects

While generally well-tolerated, Pataday can cause some side effects, which are usually mild and temporary.

Ocular Side Effects:
- Blurred vision
- Eye burning or stinging upon application
- Dry eye
- Foreign body sensation
Non-Ocular Side Effects:
- Headache
- Unpleasant taste (taste perversion)
- Cold or flu-like symptoms
- Weakness or fatigue

Serious side effects are rare but require immediate medical attention. These can include signs of an allergic reaction (hives, difficulty breathing, swelling of the face) or worsening eye pain and swelling.

Pataday Formulations and How They Differ

Pataday is available in several over-the-counter strengths, which determine the dosing frequency and duration of action. The different concentrations are a key consideration for consumers, as they offer flexibility based on the severity and duration of their symptoms.


Feature	Pataday Twice Daily Relief (0.1%)	Pataday Once Daily Relief (0.2%)	Pataday Once Daily Relief Extra Strength (0.7%)
Dosing Schedule	1 drop in each affected eye twice daily, every 6 to 8 hours.	1 drop in each affected eye once daily.	1 drop in each affected eye once daily.
Relief Duration	Provides up to 8 hours of relief.	Provides up to 16 hours of relief.	Provides a full 24 hours of relief.
Symptom Relief	Relieves itchy and red eyes.	Relieves itchy eyes.	Relieves itchy eyes.
Original Rx Brand	Patanol®.	Pataday®.	Pazeo®.

Pataday vs. Zaditor

Both Pataday (olopatadine) and Zaditor (ketotifen) are available over-the-counter and share a similar dual-action mechanism as antihistamines and mast cell stabilizers. However, some key differences exist:

Onset of Action: Pataday may work faster to relieve symptoms.
Dosing: Pataday offers a once-daily option, whereas Zaditor is typically dosed twice daily.
Side Effects: While both can cause eye irritation, some studies suggest Zaditor may cause more side effects, including burning sensations and headaches.
Age Range: Pataday is approved for children as young as 2 years old, while Zaditor is typically for ages 3 and older.

Conclusion

Pataday works on the body by delivering its active ingredient, olopatadine, directly to the eyes to combat allergic conjunctivitis. Its dual mechanism as a potent H1 receptor antagonist and mast cell stabilizer provides rapid and sustained relief from itchy, red, and watery eyes. By blocking the effects of histamine and preventing its release, Pataday effectively manages the allergic cascade locally, with minimal systemic absorption. The different available strengths provide customizable relief, making it a convenient and effective over-the-counter solution for seasonal and year-round eye allergies.

For more detailed product information, consult the Pataday manufacturer's website or the FDA drug label.

Frequently Asked Questions

Pataday is known for its fast-acting relief. Many users experience reduced eye itching and redness within minutes of applying the drops.

You should remove contact lenses before using Pataday eye drops. The preservative in the solution, benzalkonium chloride, can be absorbed by soft contact lenses. It is recommended to wait at least 10 minutes before reinserting your lenses.

Pataday is available in different concentrations of olopatadine. Pataday Twice Daily Relief (0.1%) provides up to 8 hours of relief, Pataday Once Daily Relief (0.2%) provides up to 16 hours, and Extra Strength Pataday (0.7%) provides a full 24 hours of relief.

Because Pataday is applied topically to the eyes, its systemic absorption is minimal, so it is considered a non-sedating antihistamine. While fatigue can be a less common side effect, it is far less likely than with oral antihistamines.

Yes, Pataday is generally considered safe for long-term use to manage persistent allergic conditions. However, if symptoms worsen or last for more than 72 hours, it is best to consult a healthcare provider.

If you experience increasing eye pain, changes in vision, or worsening redness and itching that lasts more than 72 hours, stop using Pataday and contact a doctor or pharmacist immediately. This could indicate a more serious underlying issue.

Yes, Pataday is approved for use in children as young as 2 years old. It is important to follow the specific dosing instructions for children and the product's concentration.