Generic Name: phenylephrine (fen-il-EF-rin)
Brand Name: Neo-Synephrine
Phenylephrine is used for:
Maintaining blood pressure in certain acute low blood pressure situations. It is also used to treat blood vessel failure during shock and low blood pressure or allergic reactions caused by other medications. It may also be used to treat painful, prolonged erections (priapism).
Phenylephrine is a vasopressor. It works by constricting blood vessels and raising blood pressure.
Do NOT use phenylephrine if:
- you are allergic to any ingredient in phenylephrine
- you have an inherited condition that causes the wall of your heart to thicken, a tumor on your adrenal gland, severe high blood pressure, or an abnormally fast heartbeat
- you are taking furazolidone or have taken a monoamine oxidase (MAO) inhibitor (eg, phenelzine) in the last 14 days
Contact your doctor or health care provider right away if any of these apply to you.
Before using phenylephrine:
Some medical conditions may interact with phenylephrine. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you have high blood pressure, heart or blood vessel disease, blood clots, asthma, liver disease, intestinal problems, diabetes, an overactive thyroid, an irregular heartbeat, or low blood fluid volume
Some MEDICINES MAY INTERACT with phenylephrine. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Rauwolfia derivatives (eg, reserpine) or tricyclic antidepressants (eg, amitriptyline) because the effectiveness of phenylephrine may be decreased
- Cocaine, furazolidone, methyldopa, MAO inhibitors (eg, phenelzine), oxytocic medicines (eg, oxytocin), rauwolfia derivatives (eg, reserpine), or tricyclic antidepressants (eg, amitriptyline) because the actions and side effects of phenylephrine may be increased
- Bromocriptine, COMT inhibitors (eg, entacapone), cocaine, or droxidopa because the actions and side effects of these medicines may be increased
- Guanethidine because its effectiveness may be decreased by phenylephrine
This may not be a complete list of all interactions that may occur. Ask your health care provider if phenylephrine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.
How to use phenylephrine:
Use phenylephrine as directed by your doctor. Check the label on the medicine for exact dosing instructions.
- Phenylephrine is usually administered as an injection at your doctor's office, hospital, or clinic.
- If you are using phenylephrine at home, carefully follow the injection procedures taught to you by your health care provider.
- If the medicine contains particles or is discolored, or if the vial/container is cracked or damaged in any way, do not use it.
- If you miss a dose of phenylephrine and are taking it regularly, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.
Ask your health care provider any questions you may have about how to use phenylephrine.
Important safety information:
- Phenylephrine may cause dizziness. Do not drive, operate machinery, or do anything else that could be dangerous until you know how you react to phenylephrine. Using phenylephrine alone, with certain other medicines, or with alcohol may lessen your ability to drive or perform other potentially dangerous tasks.
- Some of these products contain sulfites, which can cause allergic reactions in certain individuals (eg, asthma patients). If you have previously had allergic reactions to sulfites, contact your pharmacist to determine if the product you are taking contains sulfites.
- Before you have any medical or dental treatments, emergency care, or surgery, tell the doctor or dentist that you are using phenylephrine.
- LAB TESTS, such as blood pressure checks, may be performed to monitor your progress or to check for side effects. Be sure to keep all doctor and lab appointments.
- Phenylephrine is not recommended for use in CHILDREN younger than 1 year of age. Safety and effectiveness in this age group have not been confirmed.
- PREGNANCY and BREAST-FEEDING: If you become pregnant, discuss with your doctor the benefits and risks of using phenylephrine during pregnancy. It is unknown if phenylephrine is excreted in breast milk. Do not breast-feed while taking phenylephrine.
Possible side effects of phenylephrine:
All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Seek medical attention right away if any of these SEVERE side effects occur:
Excitability; headache; nausea; restlessness; vomiting.
Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); chest pain; convulsions; dizziness; irregular heartbeats; mental or mood changes; pain or redness at the injection site; shortness of breath; tingling or numb hands/feet.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.
If OVERDOSE is suspected:
Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include irregular heartbeat; tingling or numbness of the hands or feet.Proper storage of phenylephrine:
Store phenylephrine at room temperature, between 59 and 86 degrees F (15 and 30 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep phenylephrine, as well as needles and syringes, out of the reach of children and away from pets.
- If you have any questions about phenylephrine, please talk with your doctor, pharmacist, or other health care provider.
- Phenylephrine is to be used only by the patient for whom it is prescribed. Do not share it with other people.
- If your symptoms do not improve or if they become worse, check with your doctor.
- Check with your pharmacist about how to dispose of unused medicine.
This information should not be used to decide whether or not to take phenylephrine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about phenylephrine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to phenylephrine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using phenylephrine.
Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.