Phentolamine

Phentolamine is a prescription medication used to reverse numbness after oral and dental procedures, to prevent and control episodes of dangerously high blood pressure, to prevent and treat accidental injection of certain drugs under the skin, and also to diagnose a condition called pheochromocytoma.

Phentolamine belongs to a group of medications called vasodilators. These drugs work by causing blood vessels to expand and allow more blood to flow through them.

Phentolamine is available in an injectable form to be given by a healthcare professional directly into tissue of the mouth, a muscle, or a vein depending on the condition being treated or diagnosed.

Common side effects of phentolamine include injection site pain, headache, and changes in heart rate.

Phentolamine can also cause dizziness. Do not drive or operate heavy machinery until you know how phentolamine affects you.

Phentolamine is used to reverse numbness after various oral and dental procedures, to prevent and control episodes of severely high blood pressure, to prevent and treat death of skin tissue in the event of accidental injection of norepinephrine under the skin, and also to diagnose pheochromocytoma.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Use this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your age

The recommended dose range of phentolamine for the treatment and prevention of episodes of severely high blood pressure is 1 mg to 5 mg injected intravenously or intramuscularly.

The recommended dose range of phentolamine for the treatment and prevention of death of skin tissue in the event of accidental injection of norepinephrine under the skin is 5 mg to 10 mg injected under the skin into the affected area.

The recommended dose range of phentolamine for the diagnosis of pheochromocytoma is 1 mg to 5 mg injected intravenously or intramuscularly.

Serious side effects have been reported with phentolamine including the following:

• Altered heart rate. Notify your healthcare provider immediately if you feel like your heart rate is changing as this may be a sign of a potentially serious side effect of phentolamine.
• Strokes. Consult with your physician about your risk for strokes while using phentolamine and if you have a family history of strokes.
• Heart attacks. Consult with your physician about your risk for heart attacks while using phentolamine and if you have a family history of heart disease.
• Severe chest pain. Notify your healthcare provider immediately if you experience severe chest pain.
• Loss of conciousness due to extremely low blood pressure. Notify your healthcare provider if you have a history of low blood pressure before using phentolamine.

Do not take phentolamine if you:

• are allergic to phentolamine or to any of its ingredients
• have a history of heart attacks or severe heart disease

Phentolamine can also cause dizziness. Do not drive or operate heavy machinery until you know how phentolamine affects you.

Serious side effects have been reported with phentolamine. See the “Phentolamine Precautions” section.

Common side effects of phentolamine include:

• injection site pain
• dizziness
• nausea
• vomiting
• skin flushing (redness and warmth)
• diarrhea
• weakness
• headache
• change in heart rate

This is not a complete list of phentolamine side effects. Ask your doctor or pharmacist for more information.

Serious side effects have been reported with phentolamine. See "Phentolamine Precautions" section.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• acetaminophen
• alfentanil
• alfuzosin
• alprazolam
• aluminum hydroxide
• amifostine
• aminophylline
• amitriptyline
• ammonium chloride
• amobarbital
• amoxapine
• amyl nitrite
• anhydrous calcium iodide
• apomorphine
• aripiprazole
• asenapine
• aspirin
• atropine
• avanafil
• baclofen
• belladonna
• brexpiprazole
• bromodiphenhydramine
• brompheniramine
• bupivacaine
• buprenorphine
• bupropion
• buspirone
• butabarbital
• butorphanol
• cabergoline
• canagliflozin
• carbetapentane
• cariprazine
• carisoprodol
• chloral hydrate
• chlorcyclizine
• chlordiazepoxide
• chlorpheniramine
• chlorpromazine
• chlorthalidone
• clobazam
• clomipramine
• clonazepam
• clonidine
• clorazepate
• clozapine
• codeine
• conjugated estrogens
• dapagliflozin
• dexmedetomidine
• dextromethorphan
• diazepam
• dihydrocodeine
• diphenhydramine
• doxepin
• droperidol
• dutasteride
• dyphylline
• empagliflozin
• ephedrine
• fenoldopam
• fentanyl
• fluoxetine
• fluphenazine
• flurazepam
• furazolidone
• garlic
• guaifenesin
• haloperidol
• hydromorphone
• hydroxyzine
• hyoscyamine
• ibuprofen
• iloperidone
• iloprost
• imipramine
• insulin products
• isocarboxazid
• licorice
• linezolid
• lithium
• lorazepam
• loxapine
• lurasidone
• maprotiline
• maraviroc
• meperidine
• meprobamate
• mesoridazine
• methadone
• methdilazine
• methocarbamol
• methotrimeprazine
• midazolam
• mirtazapine
• molindone
• morphine
• nalbuphine
• naloxone
• nefazodone
• nortriptyline
• olanzapine
• olopatadine
• orphenadrine
• oxazepam
• oxycodone
• paliperidone
• paraldehyde
• pentazocine
• pentoxifylline
• perphenazine
• phenelzine
• phenobarbital
• phenylephrine
• procarbazine
• prochlorperazine
• promazine
• promethazine
• propiomazine
• propoxyphene
• quetiapine
• rasagiline
• riociguat
• risperidone
• secobarbital
• selegiline
• sildenafil
• silodosin
• sodium nitrite
• tadalafil
• tamsulosin
• temazepam
• tetrabenazine
• thiethylperazine
• thioridazine
• thiothixene
• tizanidine
• tranylcypromine
• trazodone
• trifluoperazine
• triflupromazine
• trimeprazine
• trimipramine
• vardenafil
• verteporfin
• zaleplon
• ziprasidone
• zolpidem

 This is not a complete list of phentolamine drug interactions. Ask your doctor or pharmacist for more information.

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

phentolamine falls into category C. In animal studies, pregnant animals were given this medication and had some babies born with problems. No well-controlled studies have been done in humans. Therefore, this medication may be used if the potential benefits to the mother outweigh the potential risks to the unborn child.

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is not known if phentolamine crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using this medications.