This article describes possible interactions with phenylephrine injection. Interactions can cause a drug to have a different effect on the body than expected. Interactions can occur due to medications, alcohol, or certain health conditions.
Phenylephrine comes as a liquid solution that’s injected into a vein. It’s also available as eye drops. These forms are used for different purposes. And the interactions of phenylephrine may vary depending on the form of the drug you’re prescribed.
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Other drugs and phenylephrine
The drugs in the list below may interact with phenylephrine injection. This article doesn’t include all drugs that may interact with phenylephrine.
Drug classes or drugs that may interact with phenylephrine injection include:
- alpha-2 agonists:
- drug examples: clonidine (Nexiclon XR, others), guanfacine (Intuniv)
- what might happen: can increase the effect of phenylephrine
- alpha-blockers or drugs that block alpha receptors:
- drug examples: chlorpromazine, amiodarone (Pacerone)
- what might happen: can block the effect of phenylephrine and the alpha-blocker drug
- beta-blockers:
- drug examples: carvedilol (Coreg), metoprolol (Lopressor, Toprol XL)
- what might happen: can increase the effect of phenylephrine
- ergot alkaloids:
- drug examples: ergotamine (Ergomar), dihydroergotamine (Migranal, Trudhesa)
- what might happen: can increase the effect of phenylephrine
- monoamine oxidase inhibitors:
- drug examples: phenelzine (Nardil), selegiline (Emsam, Zelapar)
- what might happen: can increase the effect of phenylephrine
- tricyclic antidepressants:
- drug examples: amitriptyline, nortriptyline (Pamelor)
- what might happen: can increase the effect of phenylephrine
- atomoxetine (Strattera):
- what might happen: can increase the effect of phenylephrine
- atropine:
- what might happen: can increase the effect of phenylephrine
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Get free cardWhen to avoid phenylephrine
Certain health conditions or other factors could increase some risks with phenylephrine injection. Because of this, doctors may not give phenylephrine in these cases. These health conditions or other factors are called contraindications.
Here’s a contraindication for phenylephrine injection:
- Past allergic reaction to phenylephrine: If you’ve ever had an allergic reaction to phenylephrine injection, receiving it again may cause another allergic reaction.
Before your procedure, tell your doctor if the above relates to you. This information can affect whether they use phenylephrine or another medication to treat your condition.
Alcohol and phenylephrine
Phenylephrine injection is known to interact with alcohol. Alcohol lowers blood pressure. And phenylephrine is used to increase low blood pressure if you develop it during a procedure, such as surgery, or if you have septic shock.
If you’re having a procedure, you should not consume alcohol on the day you’re having the procedure. This can cause other complications beyond possible interactions with phenylephrine. If you’re admitted to a hospital for septic shock and have consumed alcohol that day, be sure to let your doctor know. This may affect the medications they prescribe you.
Talk with your doctor if you have questions about alcohol and phenylephrine.
Questions about phenylephrine and interactions
Here you’ll find answers to some common questions about phenylephrine and possible interactions.
Are there interactions between phenylephrine injection and ibuprofen?
No, phenylephrine injection and ibuprofen aren’t known to interact.
Phenylephrine injection is used to treat low blood pressure during surgery or if you develop septic shock. It’s not used long term. Taking ibuprofen after a procedure in which you received phenylephrine injection isn’t known to cause interactions.
That said, ibuprofen has many other interactions with medications and health factors. Be sure to discuss your health history and any medications you take with your doctor and pharmacist before you take ibuprofen.
Does phenylephrine injection interact with acetaminophen?
No, there’s no known interaction between phenylephrine injection and acetaminophen.
Phenylephrine injection is used to treat low blood pressure during surgery or if you develop septic shock. It’s not used long term. Taking acetaminophen after a procedure in which you received phenylephrine injection isn’t known to cause interactions. Doctors sometimes give a dose of acetaminophen at the end of a procedure to help with any pain.
Talk with your doctor or pharmacist if you have questions about taking acetaminophen after receiving phenylephrine injection.
Other interactions and phenylephrine
Interactions can occur with supplements, foods, vaccines, and some lab tests. Below you can learn whether phenylephrine injection has these interactions.
The information below doesn’t include all other possible interactions with phenylephrine.
Phenylephrine and supplements
Before any procedures, tell your doctor and pharmacist about any herbs you take, as well as vitamins and supplements. Doing so may help them determine whether phenylephrine injection is right for you.
If you have questions about interactions that may affect you, talk with your doctor or pharmacist.
Phenylephrine interactions and herbs
Phenylephrine injection may interact with St. John’s wort. This herb is often used for easing symptoms of depression.
Receiving phenylephrine while taking St. John’s wort may increase the effect of phenylephrine.
Because of this, be sure to tell your doctor if you use St. John’s wort before any procedures. This may affect whether they use phenylephrine or another medication in case you develop low blood pressure during surgery.
Phenylephrine interactions and vitamins
Phenylephrine injection isn’t known to interact with any vitamins. But this doesn’t mean interactions with vitamins can’t happen or won’t be identified later.
Because of this, be sure to tell your doctor about any vitamin product you take before any procedures.
Phenylephrine and food
Phenylephrine injection may interact with caffeine. Consuming caffeine and then receiving phenylephrine injection may raise the risk of side effects, such as tremors.
Because of this, be sure to let your doctor know if you consumed caffeine the day of your surgery. This includes consuming coffee or green tea.
Phenylephrine and vaccines
Phenylephrine injection isn’t known to interact with any vaccines. It’s safe to receive phenylephrine with the usual vaccine schedules. But this doesn’t mean interactions with vaccines can’t happen or won’t be identified later.
Talk with your doctor if you have questions about phenylephrine and vaccines.
Phenylephrine and lab tests
Phenylephrine injection isn’t known to interact with lab tests. It’s safe to have lab tests as usual after receiving phenylephrine injection. But this doesn’t mean interactions with lab tests can’t happen or won’t be identified later.
Talk with your doctor if you have questions about phenylephrine and lab tests.
Phenylephrine and cannabis or CBD
Phenylephrine injection isn’t known to interact with cannabis (commonly called marijuana) or cannabis products such as cannabidiol (CBD).
However, you should not consume cannabis or cannabis products on the day of your procedure. If you’re admitted to a hospital for septic shock and use cannabis, be sure to let your doctor know. This may affect medications they use to treat septic shock.
As with any drug or supplement, tell your doctor before taking cannabis with phenylephrine.
Note: Cannabis is illegal at a federal level but is legal in many states to varying degrees.
Health factors and phenylephrine
Certain medical conditions or other health factors may increase the risk of interactions with phenylephrine injection. Keep in mind that interactions could lead to side effects or affect how well the drug works. Before your procedure, tell your doctor about your health history. They’ll determine whether phenylephrine is safe for you.
These health conditions or other factors might interact with phenylephrine injection:
- angina
- heart conditions, such as heart failure
- nervous system conditions, including a history of spinal cord injury
- high blood pressure in the lungs
- pregnancy or breastfeeding
- past allergic reaction to phenylephrine
Preventing phenylephrine interactions
You may be able to help avoid certain interactions with phenylephrine injection. Before your procedure or if you’re admitted to a hospital for septic shock, you may want to discuss possible interactions with your doctor and pharmacist.
Things to consider include:
- Whether you drink alcohol or use cannabis.
- Other medications and herbs you take, as well as vitamins and supplements. Your doctor or pharmacist can help you fill out a medication list.
Before your procedure, it’s important to discuss your complete health history and all medications you take with your doctor. This information can affect whether they use phenylephrine or another medication for your condition.
What to ask your doctor
If you have questions about phenylephrine and possible interactions, talk with your doctor.
Questions you may want to ask your doctor before your procedure include:
- How long does phenylephrine injection stay in my system? What’s my risk of interactions after my procedure if I receive phenylephrine injection?
- If a medication I take interacts with phenylephrine injection, will I need to stop using it before my procedure?
- Does phenylephrine injection have similar interactions as other medications you may give to me during my procedure?
Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.