Dextromethorphan + Guaifenesin

What is dextromethorphan + guaifenesin?

Dextromethorphan + guaifenesin is a combination medication used to reduce cough in cats and dogs. Dextromethorphan has mild cough suppressant effects, while guaifenesin helps to loosen chest congestion. It is also used in cats and dogs to treat compulsive behavior.

This medication has not been evaluated by the U.S. Food and Drug Administration (FDA) for use in pets, so all uses are considered off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. 

In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label. 

Do not use human OTC products in animals unless under the direction of your veterinarian. Follow their directions carefully regarding product selection and dosing.

How is dextromethorphan + guaifenesin given?

• Dextromethorphan + guaifenesin is given by mouth as a tablet. It may be compounded into other forms.
• Dextromethorphan + guaifenesin may be given with or without food.
• If vomiting occurs when dosed on an empty stomach, give future doses with food or a treat.
• Follow your veterinarian’s directions and measure liquid forms of this medication carefully.

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 miss a dose, wait and give the next dose at the regularly scheduled time, and return to the regular dosing schedule. Do not give the pet two doses at once or give extra doses.

Are there any potential side effects?

Dextromethorphan + guaifenesin may cause the following side effects:

• Vomiting, diarrhea, decreased appetite
• Sleepiness
• Drooling
• Anxiety

Serious adverse reactions may occur. If any of the following signs develop, stop giving dextromethorphan + guaifenesin and contact your veterinarian immediately:

• Rapid heartbeat
• Collapse
• Muscle tension or twitching
• Incoordination
• Seizures
• Abnormal eye movements

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment and notify your veterinarian if you have any concerns.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately.  This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE dextromethorphan + guaifenesin in:

• Pets that are allergic to it
• Pets that are under 3 months old
• Pets that weigh less than 5 lb (2.27 kg)

USE WITH CAUTION in:

• Pets with liver disease
• Pets with skin allergies (atopy)
• Pets with chronic cough or wet coughs
• Pets that have recently used products such as amitraz-containing collars or selegiline
• Pets that are pregnant or lactating (safety has not been established)

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with dextromethorphan + guaifenesin including:

• Fluoxetine (Reconcile®, Prozac®)
• Metoclopramide (Reglan®)
• Opioids
• Selegiline (Anipryl®)
• Tramadol

Be sure to tell your veterinarian about any medications (including vitamins, supplements, and herbal therapies) that your pet is taking before starting any treatment.

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.
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.

How do I store dextromethorphan + guaifenesin?

• Store in a tightly sealed container, protected from moisture.
• Store at room temperature between 68°F and 77°F (20°C and 25°C).
• Store compounded forms of this medication according to the label.
• Keep the medication out of reach of children and pets.

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.