Factors that affect a sufficient dextromethorphan dose include the age of the patient, other medications the patient is receiving, and current medical conditions. Uses of dextromethorphan include quieting coughs related to viral or bacterial infections and other cough-producing conditions. It does not have antibiotic or antiviral properties, so it will not treat the actual infection.
Even a small dextromethorphan dose can cause significant side effects. These may include sleepiness, dizziness, and anxiety. In addition, nausea, vomiting, and other gastrointestinal symptoms may occur, such as diarrhea and constipation. These are especially likely if a patient takes high doses of the drug. Although less common, rashes and hives can occur, as can difficulty breathing and swelling of the throat. Swelling of the lips and throat and shortness of breath can occur with any medications, prescription or over-the-counter, and even certain foods.
Although severe side effects, such as difficulty breathing and throat swelling, are rare, they are considered to be emergency allergic reactions and will need immediate medical attention to prevent respiratory arrest. When this occurs, emergency personnel will need to know the dextromethorphan dose that the patient was taking and what he was taking it for.
Unfortunately, even with the smallest dextromethorphan dose, persistent use can lead to dextromethorphan abuse. In addition, abuse can lead to an overdose, which can prove life-threatening. Symptoms of a dextromethorphan overdose include nausea and vomiting, extreme drowsiness and lethargy, shortness of breath, and irregular or fast heart rate. When overdose is suspected, emergency medical attention should be sought immediately.
When side effects are minor, such as minimal stomach upset, the health care provider may be able to lower the dextromethorphan dose. Most likely, lower doses will still be effective, but will not cause the same side effects as higher doses. Unless side effects are intolerable, the medication can be continued until symptoms resolve.
In the event that severe side effects or adverse reactions occur, the patient or other person in his presence should call 911, take the patient directly to the emergency room or call poison control. Placing a call to poison control should only be done if the individual is conscious and breathing. If not, the patient needs immediate medical attention at a hospital.
People who are taking other medications, such as antihistamines, cardiac medications, or anti-anxiety medications may require a lower than normal dextromethorphan dose. These medications can sometimes cause drowsiness and dizziness, and taking them with a higher dextromethorphan dose may intensify the side effects and pose a danger to the patient when driving.
