Triprolidine Drug Interactions: What to Avoid and What to Tell Your Doctor

Triprolidine is an OTC antihistamine, but "over-the-counter" doesn't mean it's free from significant drug interactions. Triprolidine's two main pharmacological actions — CNS depression and anticholinergic effects — can interact with a wide range of medications and substances. Before taking triprolidine, tell your pharmacist and doctor about everything you're taking, including prescriptions, OTC medications, vitamins, and supplements.

Major Interactions: Do Not Combine These

These interactions carry serious or potentially life-threatening risks:

MAO Inhibitors (MAOIs): Major Risk. Do not take triprolidine with MAO inhibitors or within 14 days of stopping one. MAOIs include phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan), linezolid (Zyvox), and methylene blue injection. Combining MAOIs with triprolidine — especially in combination products with pseudoephedrine — can cause dangerously high blood pressure (hypertensive crisis), extreme agitation, and serotonin syndrome.

Alcohol: Major Risk. Alcohol dramatically worsens the CNS depressant and sedative effects of triprolidine. The combination can cause severe drowsiness, impaired coordination, slowed breathing, and dangerous sedation. Avoid all alcohol while taking triprolidine.

Moderate Interactions: Use With Caution

These combinations increase risk but may be used together with medical supervision:

CNS Depressants (Opioids, Benzodiazepines, Muscle Relaxants): Moderate/Major. Combining triprolidine with opioids (morphine, oxycodone, hydrocodone), benzodiazepines (alprazolam, diazepam, lorazepam), or muscle relaxants (cyclobenzaprine, baclofen) dramatically increases CNS depression. This can result in extreme sedation, respiratory depression, and in severe cases, coma or death. If you must use these medications together, your doctor should manage the combination very carefully.

Other Antihistamines: Moderate. Taking triprolidine with diphenhydramine (Benadryl), chlorpheniramine, or other antihistamines multiplies the sedation and anticholinergic effects. Never take two antihistamines simultaneously. Check all cold, allergy, and sleep medications you're taking for antihistamine ingredients.

Other Anticholinergic Medications: Moderate. Combining triprolidine with other anticholinergic drugs — such as oxybutynin, tolterodine (bladder medications), scopolamine (motion sickness), or certain antipsychotics — increases anticholinergic side effects including urinary retention, constipation, dry mouth, confusion, and increased intraocular pressure.

Buprenorphine (Suboxone, Brixio): Moderate. CNS depressants including triprolidine can enhance buprenorphine's CNS depressant effects. If you're on buprenorphine treatment, consult your prescriber before taking triprolidine.

Tricyclic Antidepressants (TCAs): Moderate. Drugs like amitriptyline, nortriptyline, and imipramine have both anticholinergic and CNS depressant effects. Combining with triprolidine compounds both risks.

Cannabis (THC): Moderate. Cannabis enhances CNS depressant effects and increases sedation when combined with triprolidine. Monitor for excessive drowsiness.

Interactions Specific to Triprolidine/Pseudoephedrine Combinations

If you're taking the combination product (pseudoephedrine + triprolidine), the pseudoephedrine component adds additional interactions:

Beta-blockers (propranolol, metoprolol, atenolol): Pseudoephedrine can reduce the antihypertensive effect of beta-blockers and increase blood pressure risk.

Other decongestants and stimulants: Do not combine with other products containing pseudoephedrine, phenylephrine, or stimulants.

Food and Supplement Interactions

Alcohol: Severe additive CNS depression (listed above as a major risk)

Valerian, kava, passionflower, and other sedating herbal supplements: May enhance CNS depression when combined with triprolidine

Grapefruit juice: No clinically significant interaction known with triprolidine specifically (unlike some antihistamines)

What to Tell Your Doctor or Pharmacist

Before taking triprolidine, inform your healthcare provider if you are taking:

Any antidepressants (especially MAOIs, TCAs, or SSRIs)

Any sleep medications, sedatives, or tranquilizers

Any opioid pain medications

Any medication for bladder, prostate, or GI conditions with anticholinergic effects

Any other cold, allergy, or sinus medications (check for overlapping ingredients)

For more information about triprolidine side effects, visit our full guide on triprolidine side effects. And if you need help locating triprolidine at a pharmacy near you, medfinder can help.