Stahist AD Drug Interactions: What to Avoid and What to Tell Your Doctor

Drug interactions can turn a safe, effective medication into a dangerous one. Stahist AD contains two active ingredients — chlorcyclizine and pseudoephedrine — and both have interactions worth knowing. Here's a complete guide to what to watch for.

The Most Dangerous Interaction: MAO Inhibitors (MAOIs)

The most serious interaction with Stahist AD is with monoamine oxidase inhibitors (MAOIs). This combination can cause a hypertensive crisis — a sudden, dangerous spike in blood pressure — and potentially serotonin syndrome.

Do NOT take Stahist AD if you have taken an MAOI in the past 14 days. MAOIs include:

Phenelzine (Nardil)

Tranylcypromine (Parnate)

Isocarboxazid (Marplan)

Selegiline (Emsam, Eldepryl) — used for Parkinson's disease and depression

Rasagiline (Azilect)

Linezolid (Zyvox) — an antibiotic with MAOI activity

Methylene blue injection — sometimes used in surgical settings

If you take or have recently taken any MAOI, contact your prescriber before using Stahist AD. Do not simply wait 14 days and self-start — confirm with your doctor first.

Blood Pressure and Heart Medications

Pseudoephedrine stimulates the cardiovascular system and raises blood pressure. This creates clinically significant interactions with several cardiac and hypertension medications:

Antihypertensives (beta-blockers, ACE inhibitors, calcium channel blockers, etc.): Pseudoephedrine can counteract blood pressure control. If you take medication for high blood pressure, consult your doctor before using Stahist AD.

Beta-blockers (metoprolol, atenolol, propranolol): When used with pseudoephedrine, beta-blockers may actually worsen the vasoconstrictive effect due to unopposed alpha-adrenergic stimulation.

Digoxin: Pseudoephedrine may increase the risk of arrhythmias in patients taking digoxin. Use with caution.

CNS Depressants: Amplified Drowsiness

Chlorcyclizine causes sedation. Combining it with other CNS depressants significantly increases this effect:

Alcohol: Significantly worsens drowsiness; avoid completely while taking Stahist AD

Benzodiazepines (alprazolam/Xanax, diazepam/Valium, lorazepam/Ativan): Additive CNS depression; increased risk of excessive sedation

Opioid pain medications: Combination increases sedation and respiratory depression risk

Muscle relaxants (cyclobenzaprine, methocarbamol, etc.): Combined sedation; may impair driving and cognitive function

Sleep aids (diphenhydramine/Benadryl, zolpidem/Ambien, doxylamine): Additive sedation; also risk of duplicate antihistamine dosing (diphenhydramine and chlorcyclizine are both antihistamines)

Other Antihistamines and Decongestants: Avoid Duplication

Do not take Stahist AD at the same time as other antihistamines or decongestants without checking with your pharmacist first. Many OTC cold and allergy products contain pseudoephedrine, phenylephrine, diphenhydramine, loratadine, cetirizine, or other antihistamines. Taking these together increases your risk of overdose and serious side effects, including seizures and hallucinations.

Always read the full ingredient list on any OTC cold, allergy, or cough medicine you use alongside Stahist AD.

Anticholinergic Medications: Compound Risk

Chlorcyclizine has anticholinergic properties. Using it with other anticholinergic medications compounds the risk of dry mouth, urinary retention, blurred vision, constipation, and cognitive impairment. Anticholinergic medications include:

Bladder medications: oxybutynin (Ditropan), tolterodine (Detrol)

Tricyclic antidepressants: amitriptyline (Elavil), nortriptyline (Pamelor)

Anti-nausea medications: promethazine (Phenergan), scopolamine

What to Tell Your Doctor and Pharmacist

Before starting Stahist AD, tell your healthcare provider about all medications you take — including prescription drugs, OTC medicines, vitamins, herbal supplements, and recreational substances. Be especially sure to mention:

Any antidepressants (especially MAOIs, but also SSRIs in some cases)

Blood pressure or heart medications

Any sedatives, sleep aids, or anxiety medications

Any other cold, allergy, or cough medications you might be taking simultaneously

See also our guide to Stahist AD side effects. And if you're looking for Stahist AD near you, medfinder.com can check pharmacies in your area on your behalf.