Chlorpheniramine is a common antihistamine used in many over-the-counter and prescription medications for the treatment of allergy, cold and flu symptoms. In the United States and Great Britain, it is usually called chlorpheniramine but in the rest of the world, is commonly known as chlorphenamine. It is usually used in medicines in the form of chlorpheniramine maleate, a variation of the basic compound. Data shows the existence of several chlorpheniramine side effects, some of which are fairly common, but which may or may not affect a particular individual, and which may vary in intensity.
By far the most common of all chlorpheniramine side effects and the one that is common to many antihistamines is drowsiness. This affects many people who take medications containing this drug, but some people are unaffected. Drowsiness can be mild to moderate, and most literature for chlorpheniramine formulations advises refraining from driving or operating heavy equipment while using it. In some individuals, especially children, it can have a somewhat opposite effect, causing restlessness and excitability.
Other common chlorpheniramine side effects include dry mouth (xerostomia) and dry airways, headaches, and nausea, which, in some individuals, can be severe and may involve vomiting. Other gastrointestinal side effects are constipation and loss of appetite. Blurred vision, mild insomnia, tinnitus, and mild dizziness are among the more common side effects. Some people taking chlorpheniramine medications experience mild sun sensitivity. These side effects are all generally mild and often do not persist, but if they become severe or difficult to cope with, it is recommended that a doctor be consulted right away as it may be a sign of a potential problem.
Although serious health problems can result from chlorpheniramine use, these kind of side effects are rare. Severe vision problems, such as partial blindness and extremely blurry vision, are potentially dangerous. Extreme gastrointestinal distress, such as excessive vomiting, cramping, and severe pains in the stomach or intestines, while possible for some users, is not normal, and if experienced, should be reported to a doctor as soon as possible. Other potentially dangerous but rare side effects are suppressed breathing function, inability or reduced ability to urinate, and confusion. Hives or skin rashes can also result, and chlorpheniramine can exacerbate certain vision and respiratory problems.