Phenylephrine (Intravenous)

Phenylephrine is an injection used to treat low blood pressure as it occurs during surgery. This drug is given into a vein by a trained professional. It is also known as Vazculep in the US.


Phenylephrine is an injection used in the treatment of low blood pressure (hypotension) that may occur during surgery. This medication is only given under the supervision of your doctor in a clinical setting. It is available in the dosage form of solution for injection.

Conditions treated?

  • Low blood pressure during surgery

Type of medication

  • Solution for injection

Side effects

Along with the intended effects of this drug, it can produce some unwanted side effects. Although not all of these side effects may be present, if you do experience any then you may need to seek medical attention.

Inform your doctor or healthcare professional immediately if you suffer from any of the following side effects whilst taking Phenylephrine.

Incidence not known

  • Blurred vision

Seek emergency help if any of the following symptoms of overdose occur:

  • Vomiting

Some side effects that occur usually don't require any medical attention. You usually find that these side effects begin to lessen or disappear completely as your body begins adjusting to the medication. However, if they are bothersome, you should contact your local pharmacist or healthcare professional for advice on ways to prevent or reduce the severity of these side effects. Check with your doctor if these symptoms persist or worsen.

Incidence not known

You may experience other side effects that are not listed above. If you notice anything unusual, seek advice from your doctor or a healthcare professional.

Remember you can report all side effects to the FDA on 1-800-FDA-1088 if you think it necessary.


The final dose of any medication will depend on a number of factors. This will include your age, weight, and height. Your doctor will also take into account any other medications you are taking, your reaction to the first dose and the specific condition you are being treated for and its severity. Final doses will be dependent on an individual basis.

IV bolus: 0.2 mg/dose every ten to fifteen minutes as required

IV infusion: an initial dose of 100 to 180 mcg/min. The typical maintenance dose is 40 to 60 mcg/min.


Drug interactions can cause unwanted severe side effects and reduce the effectiveness of either drug you are using. To help limit the risk of interactions occurring you should give your doctor a full list of any medications you are currently taking. This should include all prescription, nonprescription drugs, all vitamins and herbal remedies. It's also a good idea to inform your doctor about any other medical conditions you are currently suffering from as these too can increase your risk of interactions.

This use of this medication alongside any of the following medicines is not usually recommended. Your doctor may alter some of the medications you are taking or decide to avoid treating you with this specific drug.

  • Rasagiline

The use of this medication alongside any of the following medications is not usually recommended. In some cases, however, it may be necessary. If you are prescribed both medications, your doctor may alter the dose or frequency in which you use each medication.

  • Nortriptyline

There are over 300 drugs that can interact moderately with this drug and cause severe side effects. Let your doctor know if you are taking any of the following medications before you agree to receive this injection.

  • Acebutolol

Be aware that this list is not complete, so it's important that you tell your doctor all medications you are currently taking.

Other Medical Conditions

The presence of other medical conditions can affect the use of this drug. Ensure you inform your doctor of any other medical conditions you suffer from, especially:

The consumption of certain foods, alcohol or tobacco can affect the use and effectiveness of many medications. It's important you discuss with your doctor to find out if any foods, alcohol or tobacco will alter the effectiveness of this drug.


Before deciding to use a medication, you should discuss alongside your doctor or healthcare professional, the risks of taking the medicine, against the benefits it will offer. For this medication, the following should be considered:

Allergies Let your doctor or healthcare professional know if you have ever suffered from an allergic reaction to this medication or similar medications. You should also let them know of any other allergies you suffer from including to, animals, preservatives, dyes, and foods.

Pediatric population Appropriate studies have not been conducted on the relationship of age to the effects of phenylephrine injection in the younger population. Therefore efficacy and safety have not yet been established.

Geriatric population Appropriate studies conducted to date have not indicated a geriatric-specific problem that could limit the usefulness of phenylephrine injection in the older population. However, elderly patients are more likely to have liver, kidney, and heart problems, which could require a degree of caution when determining the final dose.

This drug is under FDA pregnancy category C. It is unknown whether phenylephrine can harm an unborn infant. Do not use this medication without prior doctor's advice if you are pregnant. Let your doctor know if you are planning to become pregnant.

This drug can pass into breast milk and could cause potential harm a nursing child. Do not use this medication without the advice of your doctor if you're currently breastfeeding a child.

Your doctor will monitor your progress closely whilst you are taking this medication. This will enable your doctor to check that the medication is working properly and decide if you should continue reeving it. They can also test for unwanted side effects via a blood test.

This medication can cause a permanent depression known as necrosis under the skin at the injection site. Inform your doctor immediately if you notice any of these side effects at the injection site: depressed or indented skin, blue-green to black skin discoloration, or pain, peeling or redness of the skin.

Don't take other medications unless they have been discussed with your doctor. This includes all prescription, nonprescription drug, over the counter drugs, vitamins, and herbal products. To do so could cause interactions or alter the effectiveness of the medication.


This medication will be stored in a hospital or other clinical setting. It should be kept refrigerated and used once the medication has been open. This medication should not freeze and it should only be handled by a trained professional.


When used correctly, this drug is successful in the treatment of low blood pressure (hypotension) during surgery. Due to a large number of interactions, it's important that you give your doctor a full list of all the current medications you are taking. The safety and efficacy of this medication have not been established in the use of children.You should inform your doctor if you are pregnant, planning on becoming pregnant or currently breastfeeding before you take this medication. This drug is given in a clinical setting via a trained professional, usually in a vein in your arm. Be aware that taking this drug with other medications that slow your breathing or make you sleepy can worsen these effects. If you have any other questions or require further information on the practical use of this drug, then get in contact with your local healthcare professional or doctor.