Cyproheptadine

What is cyproheptadine?

Cyproheptadine (brand names: Periactin®, Ciplactin®, Cyheptine®, Cyprogin®, Cyprono®, Cyprosian®, Klarivitina®, Nuran®, Periactine®, Periactinol®, Peritol®, Polytab®, Practin®, Preptin®, Supersan®, Trimetabol®) is an antihistamine used to treat itchiness and allergic skin diseases. It is also used as an appetite stimulant in cats or to treat certain toxicities. Its use in cats, dogs, and horses to treat allergic conditions, toxicities, and stimulate appetite is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is cyproheptadine given?

• Cyproheptadine is given by mouth in the form of a tablet or a liquid syrup.
• It may be given with or without food.
• If your pet vomits when dosed on an empty stomach, give future doses with food.
• Measure liquid forms carefully.
• Allow free access to fresh, clean water at all times while your pet is taking this medication.
• This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.

What if I miss giving my pet the medication?

If you are giving this medication once daily, and you miss a dose, give the dose when you remember and then continue with the regular dosing schedule.

• If you are giving this medication twice daily, skip the dose you missed and give it at the next scheduled time.
• Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Cyproheptadine may cause the following side effects: 

• Sleepiness 
• Increased appetite 
• Dry mouth 
• Excitability (in cats) 
• Vomiting 
• Diarrhea 
• Decreased appetite 

In horses, side effects may include:

• Mild depression
• Sleepiness
• Lack of appetite

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately.  This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE cyproheptadine in pets that:

• Are allergic to it
• Are undergoing skin allergy testing within the next two weeks

USE WITH CAUTION in pets that:

• Are geriatric
• Are pregnant or lactating (safety has not been thoroughly established)
• Have enlarged prostate
• Have overactive thyroid
• Have urinary obstruction
• Have severe heart disease
• Have seizures
• Have glaucoma
• Have gastrointestinal obstruction

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with cyproheptadine, including:

• Cholinergic agonists
• Central nervous system depressant medications
• Mirtazapine
• Selective serotonin reuptake inhibitors (SSRIs)
• Tramadol
• Tricyclic antidepressants

Certain medications may interact with cyproheptadine, so be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

This medication may interact with skin allergy testing, so discontinue this medication two weeks before allergy testing. It may also interact with certain thyroid levels (thyroid stimulating hormone).

Is any monitoring needed with this medication?

• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
• With long-term use, blood cell counts should be monitored.
• At home, monitor for any side effects such as those noted above. If any side effects occur, stop using the medication and contact your veterinarian.

How do I store cyproheptadine?

• Store cyproheptadine at room temperature and protect from freezing.
• The liquid form may be stored in the refrigerator or room temperature.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet’s weight and symptoms.