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

Cyproheptadine is a first-generation antihistamine with serotonin-blocking and anticholinergic properties — and those properties lead to several significant drug interactions. Some combinations are merely uncomfortable (increased sedation); others are genuinely dangerous (with MAO inhibitors). Here's everything you need to know before combining Cyproheptadine with other medications.

Most Important: MAO Inhibitors (Contraindicated)

The most dangerous interaction with Cyproheptadine involves monoamine oxidase (MAO) inhibitors. MAO inhibitors include:

Phenelzine (Nardil)

Tranylcypromine (Parnate)

Isocarboxazid (Marplan)

Selegiline (Emsam patch, Eldepryl)

Rasagiline (Azilect) — used for Parkinson's disease

Linezolid (Zyvox) — an antibiotic with MAO-inhibiting properties

Methylene blue injection

Combining Cyproheptadine with MAO inhibitors can significantly prolong and intensify its anticholinergic effects. It is contraindicated — meaning you should NOT take them together. Do not take Cyproheptadine if you have used an MAO inhibitor in the past 14 days, or are starting one soon. Alert your doctor if you are taking any of the above medications before they prescribe Cyproheptadine.

Major Interaction: CNS Depressants (Additive Sedation)

Cyproheptadine is already sedating. When combined with other CNS (central nervous system) depressants, the sedation becomes additive — potentially causing dangerous levels of drowsiness, impaired breathing, or cognitive impairment. CNS depressants to watch for include:

Alcohol — avoid entirely while taking Cyproheptadine; significantly worsens sedation and impaired coordination

Benzodiazepines (alprazolam/Xanax, diazepam/Valium, lorazepam/Ativan, clonazepam/Klonopin) — additive CNS depression

Opioid pain medications (oxycodone, hydrocodone, codeine, tramadol) — additive respiratory depression risk

Sleep medications (zolpidem/Ambien, eszopiclone/Lunesta) — excessive sedation

Muscle relaxants (cyclobenzaprine, methocarbamol, baclofen) — additive sedation

Antipsychotics (quetiapine, olanzapine, haloperidol) — additive sedation and anticholinergic effects

Cough and cold products containing antihistamines (diphenhydramine, doxylamine) — dual antihistamine use increases sedation and anticholinergic risk

Moderate Interaction: SSRIs and SNRIs

Cyproheptadine blocks serotonin receptors. When used alongside selective serotonin reuptake inhibitors (SSRIs like fluoxetine, sertraline, escitalopram) or serotonin-norepinephrine reuptake inhibitors (SNRIs like venlafaxine, duloxetine), Cyproheptadine may partially reduce the therapeutic effect of the antidepressant.

On the flip side, this interaction is deliberately used clinically: Cyproheptadine is sometimes prescribed alongside SSRIs to counteract unwanted side effects like sexual dysfunction (anorgasmia). If you're taking an SSRI and your doctor prescribes Cyproheptadine, they may be managing this interaction intentionally.

Important: Do NOT combine SSRIs with Cyproheptadine without your doctor's guidance, as Cyproheptadine may reduce the effectiveness of your antidepressant.

Moderate Interaction: Anticholinergic Drugs (Additive Anticholinergic Effects)

Cyproheptadine has significant anticholinergic activity. Combining it with other anticholinergic medications amplifies these effects — leading to more severe dry mouth, constipation, urinary retention, confusion, and blurred vision. Drugs with anticholinergic properties to watch for:

Tricyclic antidepressants (amitriptyline, nortriptyline, imipramine)

Bladder medications for overactive bladder (oxybutynin, tolterodine, solifenacin)

Parkinson's medications (benztropine, trihexyphenidyl)

Antispasmodics (dicyclomine, hyoscyamine)

Some antipsychotics (chlorpromazine, thioridazine)

What to Tell Your Doctor Before Taking Cyproheptadine

Before your prescriber writes for Cyproheptadine, tell them about:

All prescription medications you take, especially MAO inhibitors, antidepressants, antipsychotics, or any sleep/anxiety medications

All OTC medications, especially cold/flu products, sleep aids, or any other antihistamines

Your alcohol use habits

Any history of glaucoma, enlarged prostate, urinary difficulty, or bowel obstruction

If you are pregnant or breastfeeding (Cyproheptadine is not recommended while breastfeeding)

The Bottom Line

Cyproheptadine's most dangerous interaction is with MAO inhibitors — this combination is contraindicated. Its sedating and anticholinergic properties also make it prone to additive interactions with CNS depressants and other anticholinergic drugs. Always give your prescriber and pharmacist a complete medication list. For related information, see: Cyproheptadine Side Effects and What Is Cyproheptadine? Uses, Dosage, and What You Need to Know.