Discussing Phenylephrine With Your Doctor and How It Works
What Should I Tell My Healthcare Provider Before Taking Phenylephrine?You should talk with your healthcare provider prior to taking this medication if you have:
- High blood pressure (hypertension)
- Heart disease
- Difficult passing urine
- An overactive thyroid (hyperthyroidism)
- An enlarged prostate (also known as benign prostatic hyperplasia, or BPH)
- Difficulty passing urine
- Kidney disease, such as kidney failure (renal failure)
- Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant (see Phenylephrine and Pregnancy)
- Breastfeeding (see Phenylephrine and Breastfeeding).
Make sure to tell your healthcare provider about any other medications you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
(Click Precautions and Warnings With Phenylephrine to learn more, including information on who should not take the drug.)
How Does It Work?Phenylephrine works by stimulating certain receptors known as alpha-adrenergic receptors. In the lining of the nose and sinuses, this action causes the blood vessels to constrict, allowing less fluid to leave the blood vessels and decreasing inflammation. This helps to relieve nasal and sinus congestion.
In the blood vessels of the body, this action causes an increase in blood pressure, which is why the medication is used in emergency situations to increase dangerously low blood pressure. In the eye, phenylephrine causes dilation of the pupil, constriction of the blood vessels, and a decongestant action.