Phenylephrine is a medication that treats symptoms due to the common cold, allergies or the flu, according to WebMD. The medication may also treat the symptoms of breathing illnesses such as bronchitis and sinusitis.
Phenylephrine works by decreasing the swelling in the ears and nose, making it easier and more comfortable to breathe, explains WebMD. This medication does not shorten or cure the common cold, and it may cause side effects such as trouble sleeping, upset stomach, headaches, dizziness, lightheadedness or a rapid heartbeat. To decrease the risk of these side effects, it is important that the patient follows all directions for dosage.
If the phenylephrine is in the form of a liquid, it is important to use a measuring device, and not a household spoon, to ensure the proper dosage, advises WebMD. If the medication is in chewable form, it is important to chew the tablet before swallowing the pill. Phenylephrine also comes in a dissolving form, and it is important to allow the tab or strip to dissolve completely, and then drink water.
The phenylephrine dosage is dependent on age, and the patient should not increase the dose without approval from a doctor, notes WebMD. Using this medication improperly may result in very serious side effects that can include seizure, hallucinations or even death.