Updated: January 25, 2026

What Is Stahist AD? Uses, Dosage, and What You Need to Know in 2026

Author

Peter Daggett

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What Is Stahist AD?
What Is Stahist AD Used For?
Stahist AD Dosage for Adults
Stahist AD Dosage for Children
How to Take Stahist AD
Who Should Not Take Stahist AD?

Stahist AD (chlorcyclizine/pseudoephedrine) is a combination antihistamine and decongestant for cold and allergy symptoms. Here's everything you need to know in 2026.

Stahist AD is a combination prescription-strength cold and allergy medication that uses two complementary ingredients to target your symptoms from multiple directions. Here's a comprehensive overview of what it is, what it treats, how to take it, and what you need to know before starting it.

What Is Stahist AD?

Stahist AD is a brand-name medication manufactured by Magna Pharmaceuticals. Its generic name is chlorcyclizine hydrochloride / pseudoephedrine hydrochloride. Each tablet contains 25 mg of chlorcyclizine (a first-generation antihistamine) and 60 mg of pseudoephedrine (a nasal decongestant). It's also available as a liquid (9.375 mg/30 mg per 5 mL).

Stahist AD is also marketed under the brand name NasOpen. Despite being technically OTC in many states, it's stored behind the pharmacy counter and requires ID to purchase due to its pseudoephedrine content.

What Is Stahist AD Used For?

Stahist AD is FDA-indicated for the temporary relief of symptoms associated with:

The common cold

Hay fever (seasonal allergic rhinitis)

Perennial (year-round) allergic rhinitis

Vasomotor rhinitis (non-allergic nasal congestion)

Allergic conjunctivitis (itchy, watery eyes from allergies)

Specific symptoms it relieves include: runny nose, nasal and sinus congestion, sneezing, itching of the nose or throat, and watery or itchy eyes.

Stahist AD Dosage for Adults

For adults and children 12 years and older:

Tablet: 1 tablet (25 mg/60 mg) every 6-8 hours; do not exceed 3 tablets in 24 hours

Liquid: 10 mL every 6 hours; do not exceed 40 mL in 24 hours

Both chlorcyclizine and pseudoephedrine start working within approximately 40 minutes of taking a dose. Effects typically last 6-8 hours.

Stahist AD Dosage for Children

For children ages 6–11 years:

Tablet: 1/2 tablet every 6-8 hours; do not exceed 1.5 tablets in 24 hours

Liquid: 5 mL every 6 hours; do not exceed 20 mL in 24 hours

Stahist AD should not be given to children under 6 years of age. Always consult a pediatrician before giving any combination cold/allergy medication to a child.

How to Take Stahist AD

Can be taken with or without food; take with food if stomach upset occurs

Use only as directed — do not exceed maximum daily doses

Do not use for more than 7 days for cold symptoms without consulting a doctor

Avoid alcohol while taking Stahist AD — it increases drowsiness

Store at room temperature, in a dry place, out of reach of children

Who Should Not Take Stahist AD?

Do not take Stahist AD if you:

Have taken an MAOI (monoamine oxidase inhibitor) within the past 14 days

Are allergic to chlorcyclizine or pseudoephedrine

Have severe or uncontrolled high blood pressure

Have severe coronary artery disease or arrhythmias

Talk to your doctor before using Stahist AD if you have high blood pressure, heart disease, glaucoma, BPH, hyperthyroidism, or COPD/emphysema.

For a full review of Stahist AD's side effects, see our guide to Stahist AD side effects. And if you're struggling to find it at a pharmacy near you, visit medfinder.com for help.

Frequently Asked Questions

No. Stahist AD is a combination medication — it contains both a first-generation antihistamine (chlorcyclizine) AND a decongestant (pseudoephedrine). A regular antihistamine like Benadryl only contains diphenhydramine with no decongestant component. Stahist AD provides broader symptom relief for both congestion and allergy symptoms.

Stahist AD is typically intended for short-term use (up to 7 days for cold symptoms). For chronic allergic conditions (perennial rhinitis), some patients may use it for longer periods under physician supervision. Discuss long-term use with your doctor, as both chlorcyclizine and pseudoephedrine have side effects that may be more problematic with daily use.

Both are antihistamine/decongestant combinations with pseudoephedrine. The key difference is the antihistamine: Stahist AD uses chlorcyclizine (first-generation, sedating), while Claritin-D uses loratadine (second-generation, non-drowsy). Claritin-D is more widely available and has a 12 or 24-hour formulation, while Stahist AD is dosed every 6-8 hours.

In most U.S. states, Stahist AD technically does not require a prescription — it is classified as an OTC product available behind the pharmacy counter. However, you must show valid photo ID to purchase it due to pseudoephedrine regulations. Some pharmacies may require a prescription, and insurance coverage requires one.

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