There are few things more frightening than having or witnessing an anaphylactic reaction. The symptoms can go from bad to worse very quickly, and may include:

If you witness someone having anaphylactic symptoms, or you are having symptoms, call emergency services immediately.

If you’ve had a severe allergic reaction in the past, your doctor may have prescribed an emergency epinephrine injection. Getting a shot of emergency epinephrine as quickly as possible can save your life — but what happens after the epinephrine?

Ideally, your symptoms will begin to improve. Sometimes they can even resolve completely. This may lead you to believe that you’re out of the woods and no longer in any danger. However, this isn’t the case. A trip to the emergency room (ER) is still required, no matter how well you feel after your anaphylactic reaction.

Epinephrine usually relieves the most dangerous symptoms of anaphylaxis quickly — including throat swelling, trouble breathing, and low blood pressure. It’s the treatment of choice for anyone experiencing anaphylaxis. Yet you need to administer epinephrine in the first few minutes after the allergic reaction starts for it to be most effective.

Keep in mind that you should only give epinephrine to a person who’s been prescribed the medication. You should also follow the instructions carefully. Dosages vary, and individual medical conditions can affect how a person reacts to it. For instance, epinephrine could precipitate a heart attack in someone with heart disease. This is because it speeds up the heart rate and raises blood pressure.

Give an injection if you or someone else has been exposed to an allergic trigger and:

  • has trouble breathing
  • has swelling or tightness in their throat
  • feels dizzy

Also use it in children who:

Before using the auto-injector, read the instructions. Each device is a little bit different.

In general, to give epinephrine, you should follow the steps below:

  1. Open or pull off the auto-injector cap.
  2. Hold the injector in your fist with the tip pointing down.
  3. Place it against your thigh or the thigh of the person who’s having the reaction.
  4. Press down and hold for two to three seconds.
  5. Remove the auto-injector.
  6. Place the auto-injector back into its case, and take it to a hospital for disposal.

After you give the injection, call 911 or your local emergency services if you haven’t already done so. Tell the dispatcher about the anaphylactic reaction.

While you wait for medical help to arrive, take these steps to keep yourself or the person who’s having the reaction safe:

  • Remove the source of the allergy. For example, pull out the stinger if a bee sting caused the reaction.
  • Lay the person flat. Raise their legs and cover them with a blanket to keep them warm.
  • If they’re throwing up or having trouble breathing, sit them up or lay them on their side.
  • Give other medicines, such as an antihistamine or an inhaler, if they’re wheezing.
  • If symptoms don’t improve, give the person another injection of epinephrine. Doses should occur at least 5 minutes apart.

An injection of emergency epinephrine could save your life after an anaphylactic reaction. However, the injection is only one part of the treatment you may need. Everyone who’s had an anaphylactic reaction needs to be examined and monitored in an emergency room. This is because anaphylaxis isn’t always a single reaction. The symptoms can rebound, returning hours or even days after you get an epinephrine injection.

Most cases of anaphylaxis happen quickly and fully resolve after they’re treated. However, sometimes the symptoms get better and then start again a few hours later. Sometimes they don’t improve hours or days later.

Anaphylaxis reactions happen in three different patterns:

  • Uniphasic reactions. This type of reaction is the most common. Symptoms peak within 30 minutes to an hour after you’re exposed to the allergen. Symptoms get better within an hour, with or without treatment, and they don’t return.
  • Biphasic reactions. Biphasic reactions occur when symptoms go away for an hour or more, but then return without your being re-exposed to the allergen.
  • Protracted anaphylaxis. This type of anaphylaxis is relatively rare. The reaction can last for hours or even days without completely resolving.

Recommendations from the Joint Task Force (JTF) on Practice Parameters advise that people who’ve had an anaphylactic reaction be monitored in an ER for four to eight hours afterward. The task force also recommends that they be sent home with a prescription for an epinephrine auto-injector—and an action plan on how and when to administer it—due to the possibility of a recurrence.

The risk of a rebound anaphylactic reaction makes proper medical evaluation and aftercare crucial, even for people who feel fine after treatment with epinephrine.

When you go to the emergency department to be treated for anaphylaxis, the doctor will do a full examination. The medical staff will check your breathing and give you oxygen. If you continue to wheeze and have trouble breathing, you may be given other medicines by mouth, intravenously, or via an inhaler to help you breathe more easily.

These medications can include:

  • bronchodilators
  • steroids
  • antihistamines

You’ll also get more epinephrine if you need it. You’ll be carefully observed and given immediate medical attention if your symptoms come back or get worse. People with very severe reactions may need a breathing tube or surgery to open their airways. Those who don’t respond to epinephrine might need to get this drug through a vein.

Once you’ve been successfully treated for an anaphylactic reaction, your goal should be to avoid another one. The best way to do that is to stay away from your allergy trigger. If you’re not sure what caused your reaction, see an allergist for a skin prick or blood test to identify your trigger.

If you’re allergic to a certain food, read product labels to make sure you don’t eat anything containing it. When you eat out, let the server know about your allergies.

If you’re allergic to insects, wear an insect repellant whenever you go outdoors in the summer. Never swat at bees, wasps, or hornets. They might sting you. Instead, slowly move away from them.

If you’re allergic to medication, tell every doctor that you visit about your allergy, so they don’t prescribe that drug for you. Also let your pharmacist know. Consider wearing a medical alert bracelet to let emergency responders know that you have a drug allergy.

Always carry an epinephrine auto-injector with you, in case you do encounter your allergy trigger in the future. If you haven’t used it in a while, check the date to make sure that it hasn’t expired.