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How does this medication work? What will it do for me?

Epinephrine belongs to a family of medications called sympathomimetics. These medications resemble chemicals that are normally found in our bodies and are released during stressful situations, such as when we are scared, anxious, or angry.

Epinephrine is used for the emergency treatment of severe allergic reactions (anaphylaxis) to insect bites, insect stings, food, medication, as well as other allergens (e.g., latex). During a severe allergic reaction, blood pressure can become dangerously low, breathing can become difficult, and the face and throat can swell. Other signs and symptoms can include hives, flushing, fast heart rate, paleness, weakness, dizziness, stomach cramps, nausea, vomiting, and diarrhea. Epinephrine works to reverse these effects.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

How should I use this medication?

The usual dose of epinephrine is based on your body weight, your risk of experiencing a serious allergic reaction, and your ability to tolerate the medication. The usual dose for children and adults who weigh 30 kg or more is 0.3 mg. For adults and children who weigh 15 kg to 30 kg, the dose is 0.15 mg. For children who weigh less than 15 mg, other forms of injectable epinephrine may be prescribed.

The medication is injected into the thigh with use of an autoinjector, which is a device that resembles a pen. To use the autoinjector, remove the caps on each end. Then, place the red tip of the pen against the thigh and press hard, holding it there to let the plunger activate (the needle will be pushed into the thigh muscle to inject a dose of epinephrine). The needle can go through clothes. Hold the pen against the thigh as you count to 10. After counting to 10, remove the device from your thigh. Seek medical attention immediately.

If the symptoms have not improved within about 10 minutes, administer a second dose. Prepare the second dose by unscrewing the rounded tip, pulling the syringe from the barrel and sliding the yellow collar off the plunger. Inject the dose by placing the needle into the thigh and pushing the plunger. It is important to know how to use the autoinjector. If you are not sure, ask your doctor, nurse, or pharmacist for a demonstration.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

Store this medication at room temperature, protect it from light, and keep it out of the reach of children. The pen should be stored in its original tube. Do not use it if the solution is darker than light yellow, develops a pinkish colour, or has particles in it.

What form(s) does this medication come in?

Twinject is no longer being manufactured for sale in Canada. For brands that may still be available, search under epinephrine. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

Who should NOT take this medication?

Epinephrine should not be used by anyone who is allergic to epinephrine or to any of the ingredients of the medication.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • anxiety
  • dizziness
  • fear
  • headache
  • paleness
  • restlessness
  • shakiness
  • tenseness
  • weakness

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Let your doctor or emergency medical attendant know immediately if any of the following side effects occur:

  • chest pain
  • difficulty breathing
  • infection at the injection site (e.g., persistent redness, swelling, tenderness, warmth)
  • increased heart rate or pounding heartbeat
  • irregular heartbeat
  • symptoms of a stroke (e.g., sudden blurred vision, difficulty speaking, dizziness, headache, weakness)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Accidental injection: If epinephrine is accidentally injected into areas such as the hands or feet, go to the nearest emergency room for treatment. Epinephrine should only be injected into the thigh.

Asthma: People who have asthma may experience difficulty breathing after using epinephrine. If you have asthma, make sure you inform any emergency professionals that you have asthma and have used epinephrine. Discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Diabetes: People with diabetes may experience a temporary increase in blood glucose level after using epinephrine. If you have diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Be sure to tell any emergency professionals that you have diabetes and that you have used epinephrine.

Glaucoma: The symptoms of glaucoma can be made worse when epinephrine is used. If you have glaucoma, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Heart disease: Epinephrine has many effects throughout the body. It narrows the blood vessels, which in turn can increase blood pressure, heart rate and possibly cause irregular heartbeat. If you have heart disease, including high blood pressure, abnormal heartbeat or are taking medications that increase the risk of an irregular heartbeat (e.g., digoxin, amiodarone, sotalol, procainamide), or have an overactive thyroid, these conditions can be made worse for a short period of time, by using epinephrine. Discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication and whether any special monitoring is needed.

Be sure to tell any emergency professionals if you have any of these conditions and that you have used epinephrine.

Medical attention: Since the signs and symptoms of an allergic reaction may return after using this medication, it is important to get immediate medical attention after using it. You should be close to a hospital or emergency medical help for at least 24 hours after the start of your allergic reaction.

Skin infection: Severe skin infection has been known to occur after using epinephrine injections, although this is rare. If you experience ongoing redness, warmth, swelling, or tenderness at the injection site, seek immediate medical attention.

Parkinson's disease (PD): People with PD may experience temporarily worsened symptoms of PD after using epinephrine.

Pregnancy: This medication should only be used during pregnancy if the benefits outweigh the risks.

What other drugs could interact with this medication?

There may be an interaction between epinephrine and any of the following:

  • alpha-blockers (e.g., alfuzosin, doxazosin, tamsulosin)
  • amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
  • antipsychotics (e.g., clozapine, haloperidol)
  • atomoxetine
  • beta-blockers (e.g., propranolol, atenolol, metoprolol)
  • bromocriptine
  • caffeine
  • cannabis
  • cocaine
  • decongestant cold medications (e.g., phenylephrine, pseudoephedrine)
  • decongestant eye drops and nose sprays (e.g., naphazoline, oxymetazoline, xylometazoline)
  • diabetes medications (e.g., canagliflozin, glyburide, insulin, liraglutide, linagliptin, metformin, rosiglitazone)
  • entacapone
  • ergot alkaloids (e.g., ergotamine, ergonovine)
  • fast-acting bronchodilators (e.g., salbutamol, terbutaline)
  • general anesthetics (medications used to put people to sleep before surgery)
  • levothyroxine
  • linezolid
  • long-acting bronchodilators (e.g., formoterol, salmeterol)
  • medications used to treat an abnormal heart rhythm (e.g., amiodarone, sotalol, procainamide)
  • methylphenidate
  • modafinil
  • monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
  • nabilone
  • norepinephrine
  • ozanimod
  • serotonin/norepinephrine reuptake inhibitors (SNRIs; e.g., desvenlafaxine, duloxetine, venlafaxine)
  • spironolactone
  • theophyllines (e.g., aminophylline, theophylline)
  • tricyclic antidepressants (e.g., amitriptyline, desipramine, nortriptyline)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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