Top of the pageCheck Your SymptomsAllergic Reaction Topic OverviewAllergies are an overreaction of the body’s
natural defense system that helps fight infections (immune system).
The immune system normally protects the body from viruses and bacteria by
producing
antibodies to fight them. In an
allergic reaction, the immune system starts fighting
substances that are usually harmless (such as
dust mites, pollen, or a medicine) as though these
substances were trying to attack the body. This overreaction can cause a rash,
itchy eyes, a runny nose, trouble breathing, nausea, and diarrhea. An allergic reaction may not occur the first time you are exposed to an
allergy-producing substance (allergen). For example, the first time
you are stung by a bee, you may have only pain and redness from the sting. If
you are stung again, you may have
hives or trouble breathing. This is caused by the
response of the immune system. Many people will have some problem
with allergies or allergic reactions at some point in their lives. Allergic
reactions can range from mild and annoying to sudden and life-threatening. Most
allergic reactions are mild, and home treatment can relieve many of the
symptoms. An allergic reaction is more serious when severe allergic reaction
(anaphylaxis) occurs, when
allergies cause other problems (such as nosebleeds,
ear problems, wheezing, or coughing), or when home treatment doesn’t
help. Allergies often occur along with other diseases, such as
asthma,
ear infections,
sinusitis, and
sleep apnea. For more information, see the topic
Allergic Rhinitis. Types of allergies There are many types of allergies.
Some of the more common ones include: Food allergies, which are more common
in children than adults. Food allergies are most common in people who have an
inherited tendency to develop allergic conditions. These people are more likely
to have asthma and other allergies. For more information, see the topic
Food Allergies. Medicine allergies. Many prescription
and nonprescription medicines can cause an allergic reaction. Allergic
reactions are common and unpredictable. The seriousness of the allergic
reaction caused by a certain medicine will vary. Allergies to insect venom. When you are stung by an
insect, poisons and other toxins in the insect’s venom enter your skin. It is
normal to have some swelling, redness, pain, and itching at the site of a
sting. An allergic reaction to the sting occurs when your body’s immune system
overreacts to the venom of stinging insects. For more information, see the
topic Allergies to Insect Stings. Allergies to animals, which are more likely to cause breathing problems than skin
problems. You may be allergic to your pet’s dead skin (dander), urine, dried
saliva, or hair. Allergies to natural rubber (latex).
Some people develop allergic reactions after repeated contact with latex,
especially latex gloves. Allergies that develop from exposure to a
particular inhaled substance in the workplace. These are called
occupational asthma. Allergies to
cosmetics, such as artificial nails, hair extensions, and henna tattoos.Seasonal allergies show up at the same time of the
year every year and are caused by exposure to pollens from trees, grasses, or
weeds. Hay fever is the most common seasonal allergy. Allergies
that occur for more than 9 months out of the year are called perennial
allergies. Year-round symptoms (chronic allergies) are
most likely to occur from exposure to
animal dander, house dust, or
mold. Check your symptoms to decide if and when you should see a doctor.Health ToolsHealth Tools help you make wise health decisions or take action to improve your health.
Decision Points focus on key medical care decisions that are important to many health problems.
Allergies: Should I Take Allergy Shots? Allergies: Should I Take Shots for Insect Sting Allergies?
Actionsets are designed to help people take an active role in managing a health condition.
Allergies in Children: Giving an Epinephrine Shot to a Child Allergies: Giving Yourself an Epinephrine ShotCheck Your Symptoms Are you concerned about an allergic reaction?YesAllergic reaction concernsNoAllergic reaction concernsHow old are you?Less than 12 yearsLess than 12 years12 years or older12 years or olderAre you male or female?MaleMaleFemaleFemaleCould you be having a severe allergic reaction?This is more likely if you have had a bad reaction to something in the past.YesPossible severe allergic reaction (anaphylaxis)NoPossible severe allergic reaction (anaphylaxis)Do you have symptoms of shock?The symptoms in an adult or older child are different than the symptoms in a young child.YesSymptoms of shockNoSymptoms of shockHave you ever had a severe allergic reaction?A severe allergic reaction affects the whole body. Your doctor may have called it anaphylaxis.YesHistory of severe allergic reactionNoHistory of severe allergic reactionHave you been exposed to the same thing (or something similar to it) that caused a severe reaction in the past?For example, this could be an insect, a certain food, or a type of medicine or drug.YesReexposed to substance that caused past severe reactionNoNo new exposure to substance that caused past severe reactionNot surePossibly reexposed to substance that caused past severe reactionAre you having any symptoms of an allergic reaction now, even mild ones?If you’ve ever had a severe reaction to the same thing that’s causing your symptoms now, treat this as an emergency. Mild symptoms quickly may become severe.YesHistory of severe reaction with symptoms nowNoHistory of severe reaction with symptoms nowAre you having trouble breathing (more than a stuffy nose)?YesDifficulty breathing more than a stuffy noseNoDifficulty breathing more than a stuffy noseIs there any new swelling?YesNew swellingNoNew swellingAre the lips, tongue, mouth, or throat swollen?YesSwelling of lips, tongue, mouth, or throatNoSwelling of lips, tongue, mouth, or throatDid the lips, tongue, mouth, or throat swell quickly?YesRapid swelling of lips, tongue, mouth, or throatNoRapid swelling of lips, tongue, mouth, or throatDoes swelling involve the palms of the hands, the soles of the feet, or the area from one large joint to another, such as from the ankle to the knee?YesSwelling is across two joints, on soles of feet, or on palms of handsNoSwelling is across two joints, on soles of feet, or on palms of handsIs the swelling getting worse (over hours or days)?YesSwelling is getting worseNoSwelling is getting worseDid you get an epinephrine shot to treat the reaction?YesHas had epinephrine shotNoHas had epinephrine shotIs most of your body covered in hives?Hives are raised, red, itchy patches of skin. They usually have red borders and pale centers. They may seem to move from place to place on the skin.YesHives covering most of bodyNoHives covering most of bodyDid the hives appear within the past 3 hours?YesHives appeared within past 3 hoursNoHives appeared within past 3 hoursAre there any symptoms of infection?YesSymptoms of infectionNoSymptoms of infectionDo you think you may have a fever?YesPossible feverNoPossible feverAre there red streaks leading away from the area or pus draining from it?YesRed streaks or pusNoRed streaks or pusDo you have diabetes, a weakened immune system, peripheral arterial disease, or any surgical hardware in the area?”Hardware” includes things like artificial joints, plates or screws, catheters, and medicine pumps.YesDiabetes, immune problems, peripheral arterial disease, or surgical hardware in affected areaNoDiabetes, immune problems, peripheral arterial disease, or surgical hardware in affected areaDoes your skin itch?YesItchy skinNoItchy skinIs the itching severe?Severe means that you are scratching so hard that your skin is cut or bleeding.YesSevere itchingNoSevere itchingHas the itching interfered with sleeping or normal activities for more than 2 days?YesItching has disrupted sleep or normal activities for more than 2 daysNoItching has disrupted sleep or normal activities for more than 2 daysCould you be having an allergic reaction to a medicine or a vaccine?Almost any medicine or vaccine can cause an allergic reaction. Think about whether the problem started soon after you began using a new medicine or a higher dose of a medicine. Or did it start after you got a shot or vaccine?YesMedicine may be causing allergic reactionNoMedicine may be causing allergic reactionHave your symptoms lasted longer than 2 weeks?YesSymptoms for more than 2 weeksNoSymptoms for more than 2 weeksMany things can affect how your body responds to a symptom and what kind
of care you may need. These include:Your age. Babies and older
adults tend to get sicker quicker.Your overall health. If you have a condition such as diabetes, HIV, cancer, or heart
disease, you may need to pay closer attention to certain symptoms and seek care
sooner.Medicines you take. Certain
medicines, herbal remedies, and supplements can cause symptoms or make them
worse.Recent health events, such as surgery
or injury. These kinds of events can cause symptoms afterwards or make them
more serious.Your health habits and lifestyle, such as eating and exercise habits, smoking, alcohol or drug
use, sexual history, and travel. Try Home TreatmentYou have answered all the questions. Based on your answers, you may be
able to take care of this problem at home. Try home treatment to relieve the
symptoms. Call your doctor if symptoms get worse or you have any
concerns (for example, if symptoms are not getting better as you would expect).
You may need care sooner.HomeTreatmentWhereToGo Symptoms of infection may
include:Increased pain, swelling, warmth, or redness in or
around the area.Red streaks leading from the area.
Pus draining from the area. A fever.Symptoms of a severe allergic reaction
(anaphylaxis) may include:The sudden appearance of raised, red areas (hives)
all over the body.Rapid swelling of the throat, mouth, or tongue.Trouble
breathing.Passing out (losing consciousness). Or you may feel very lightheaded or suddenly feel weak, confused,
or restless. A severe reaction can be life-threatening. If you have had a
bad allergic reaction to a substance before and are exposed to it again, treat
any symptoms as an emergency. Even if the symptoms are mild at first, they may
quickly become very severe.Symptoms of difficulty breathing can range from mild to severe. For example:You may feel a little out of breath but still be able to talk (mild difficulty breathing), or you may be so out of breath that you cannot talk at all (severe difficulty breathing).It may be getting hard to breathe with activity (mild difficulty breathing), or you may have to work very hard to breathe even when you’re at rest (severe difficulty breathing).Certain health conditions and medicines weaken the immune system’s ability to fight off infection and
illness. Some examples in adults are:Diseases such as diabetes, cancer, heart disease,
and HIV/AIDS.Long-term alcohol and drug
problems.Steroid medicines, which may be used to treat a variety
of conditions.Chemotherapy and radiation therapy for
cancer.Other medicines used to treat autoimmune
disease.Medicines taken after organ transplant.Not
having a spleen.Shock is a life-threatening condition that may quickly occur
after a sudden illness or injury. Symptoms of shock (most of which will be present) include:Passing out (losing consciousness).Feeling very dizzy or
lightheaded, like you may pass out.Feeling very weak or having
trouble standing.Not feeling alert or able to think clearly. You
may be confused, restless, fearful, or unable to respond to questions.Shock is a life-threatening condition that may occur quickly
after a sudden illness or injury. Symptoms of shock in a child may include:Passing out (losing consciousness).Being very sleepy or hard
to wake up. Not responding when being touched or talked to.
Breathing much faster than usual. Acting confused.
The child may not know where he or she is. Make an Appointment Based on your answers, the problem may not improve without medical
care.Make an appointment to see your doctor in the
next 1 to 2 weeks. If appropriate, try home treatment while you
are waiting for the appointment.If symptoms get worse or you have
any concerns, call your doctor. You may need care sooner.HomeTreatmentWhereToGo Seek Care TodayBased on your answers, you may need care soon. The
problem probably will not get better without medical care.Call your doctor today to discuss the symptoms
and arrange for care.If you cannot reach your doctor or you don’t
have one, seek care today.If it is evening, watch the symptoms and
seek care in the morning.If the symptoms get worse, seek care
sooner.HomeTreatmentWhereToGo Seek Care NowBased on your answers, you may need care right away. The problem is likely to get worse without medical care.Call your doctor now to discuss the symptoms and
arrange for care.If you cannot reach your doctor or you don’t have
one, seek care in the next hour.You do not need to call an
ambulance unless:
You cannot travel safely either by driving
yourself or by having someone else drive you.You are in an area
where heavy traffic or other problems may slow you down.HomeTreatmentWhereToGo Call 911 NowBased on your answers, you need emergency care.Call 911 or other emergency services now.If you have an epinephrine shot, use it while you wait for help to arrive. Follow the directions on the label about how to give the shot. Seek Care NowBased on your answers, you may need care right away. The problem is likely to get worse without medical care.Call your doctor now to discuss the symptoms and
arrange for care.If you cannot reach your doctor or you don’t have
one, go to the emergency room now. You may have a reaction after the
epinephrine wears off.You do not need to call an ambulance unless:

You cannot travel safely either by driving
yourself or by having someone else drive you.You are in an area
where heavy traffic or other problems may slow you down.HomeTreatmentWhereToGo Home TreatmentYou can use home treatment to relieve symptoms of: Itching or hives.
Avoid more contact with whatever you think is causing the
hives. A sore throat caused by postnasal drip. People age 8 years or older can gargle with
warm salt water at least once each hour to help ease throat soreness. Hay fever or other seasonal allergies.
Use saline drops or a humidifier to help clear a stuffy nose. Or take an allergy medicine that’s specific to your symptoms. Be safe with medicines. Read and follow all instructions on the label. Allergies that are worse in damp weather. Mold may be the cause of allergies that get worse in damp
weather. Mold produces spores that move, like pollen, in outdoor air during
warmer months. During winter months, indoor molds can also be a
problem. Indoor allergies. Newer, energy-saving homes that are
built with double- or triple-paned windows and more insulation keep heat and allergens indoors. Allergies to a pet or other animal. When allergies are worse around pets, symptoms may be caused by
your pet’s dead skin (dander), urine, dried saliva, or hair. Try a nonprescription medicine for the relief of itching,
redness, and swelling. Be sure to follow the
nonprescription medicine precautions.
An
antihistamine medicine, such as a nondrowsy one like loratadine (Claritin) or one that might make you sleepy like diphenhydramine (Benadryl), may help relieve itching, redness, and swelling. Don’t give
antihistamines to your child unless you’ve checked with the doctor first.
Calamine
lotion or hydrocortisone cream applied to the skin may help relieve itching.For tips on how to treat dry and irritated skin, see the topic
Dry Skin and Itching. For information on
how to treat an insect bite or sting, see the topic
Insect Bites and Stings and Spider Bites. Symptoms to watch for during home treatment Call your doctor if any of the following occur during home treatment: Trouble breathing, wheezing, or tightness in
the chest develops. Swelling of the throat, tongue, lips, or mouth
develops. Hives develop or get
worse. Swelling gets worse. A
skin infection develops. Symptoms have not
improved after 2 weeks of home treatment. Symptoms become more
severe or more frequent.PreventionTo prevent problems with severe allergic
reactions: If you or your child has had a severe allergic
reaction, talk to your doctor about getting a prescription for epinephrine. Learn how and when to give yourself an epinephrine shot, and have it
near you at all times. Allergies: Giving Yourself an Epinephrine Shot Allergies in Children: Giving an Epinephrine Shot to a Child If you have had an allergic reaction, wear a
medical identification tag to alert others to your allergies. If
you know you have an allergy to a medicine, be sure any new doctor knows about
your allergy before prescribing a medicine for you. Ask your doctor if immunotherapy might help you. For this treatment, you get allergy shots or use pills that have a small amount of certain allergens in them. Your body “gets used to” the allergen, so you react less to it over time. This kind of treatment may help prevent or reduce some allergy symptoms.
Allergies: Should I Take Allergy Shots? If you have had
a severe allergic reaction to an insect bite or sting,
avoid the insect that caused the reaction. Allergy
shots may help reduce the severity of your reactions to insects. Allergies: Should I Take Shots for Insect Sting Allergies?To prevent seasonal or year-round allergy reactions: Control exposure to outdoor allergens. Limit the
time you spend outside during allergy season. This may be the best approach to
controlling your symptoms. If you have a seasonal allergy:
During the peak of the pollen or mold season,
consider taking your vacation in a place that has fewer of these
substances. Exercise regularly. Exercise produces adrenaline, a
natural way to relieve a stuffy nose. But exercising outdoors may also
expose you to more pollen or mold spores. Control exposure to indoor allergens. Newer,
energy-saving homes built with double- or triple-paned windows and more
insulation keep
allergens and heat indoors.
Use an air conditioner or air purifier with a
high-efficiency particulate air (HEPA) filter. Keep the house aired
out and dry. Keep the moisture level below 50%. Use a dehumidifier during humid
weather. Dust and vacuum 1 to 2 times a week. Use a vacuum cleaner
with a HEPA filter, which collects dust-mite particles and pollen. Standard
paper bag filters may allow the stirred-up allergens to escape back into the
room. Avoid carpet, upholstered furniture, and heavy drapes that
collect dust. Vacuuming doesn’t pick up dust mites. Remove rugs and
wall-to-wall carpeting. Talk with your family about this measure and how this
will affect family life. Replace drapes and blinds with roll-down shades or
washable curtains. Damp mop the floor once a day. Vacuum the walls,
ceiling, closet, and the backs of the furniture once a week to get rid of as
much dust as you can. Use baking soda, mineral oil, club soda, or
vinegar to clean instead of using harsher cleaning solutions that can produce
allergic reactions. Contact a pest control service, if necessary,
to get rid of cockroaches. Cockroaches and dead insects may provoke allergic
responses if you have allergic asthma. Avoid tobacco smoke, smoke
from wood-burning stoves, and fumes from kerosene heaters. Keep air
registers closed if there is a pet in the house. This will reduce the amount of
animal dander circulating in the house, especially in
the bedroom. Repair any water-damaged areas from leaking roofs or
basements. These areas can be prime mold-growing areas. Control exposure to animal dander (dead skin or scales from animals). Indoor pets can spread dander and other pet-related allergens such as urine and dried saliva throughout your home. Cats in particular spread dried saliva, but other small animals such as mice and gerbils can spread it too. Hair is often not the problem. Short-haired animals are no less of a problem than long-haired ones.Keep the pet outside of the house or at least out
of the bedroom. Bathe your pet once a week. Ask a family member who does not have allergies to clean your pet’s litter box. Keep a caged pet, such as a gerbil, outside your home in a garage or shed. Consider finding your pet a new home if your
symptoms are severe. Be sure to tell your child’s school staff about his
or her allergies. This is important so the school knows how to help your child
if he or she has an allergic reaction.Preparing For Your AppointmentTo prepare for your appointment, see the topic Making the Most of Your Appointment. You can help your
doctor diagnose and treat your condition by being prepared to answer the
following questions: What are your allergy symptoms? How
long have you had these symptoms? Do you have an idea of what is
causing your symptoms? Are your allergies present all year, or do
they get better or worse with different seasons? Have you had an immunization (vaccine) shot recently? What have you
tried at home to decrease your symptoms? Has it helped? What
prescription or nonprescription medicines have you tried in the past? What
worked and what didn’t? What other prescription and nonprescription
medicines are you taking? Have you recently gotten a tattoo or body
piercing? Do you have any
health risks?CreditsByHealthwise StaffPrimary Medical Reviewer William H. Blahd, Jr., MD, FACEP – Emergency Medicine Kathleen Romito, MD – Family Medicine Adam Husney, MD – Family Medicine Specialist Medical Reviewer E. Gregory Thompson, MD – Internal Medicine Current as ofJanuary 29, 2018 Top of PageNext Section:
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January 29, 2018Author:
Healthwise Staff Medical Review:
William H. Blahd, Jr., MD, FACEP – Emergency Medicine & Kathleen Romito, MD – Family Medicine & Adam Husney, MD – Family Medicine & E. Gregory Thompson, MD – Internal Medicine