Allergies 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, difficulty 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 difficulty breathing. This is caused by the response of the immune system.
Most 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 does not 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. For more information, see the topic Allergy to Natural Rubber (Latex).
- 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. Between 20 and 40 million people in the United States are affected by perennial allergies.
Year-round symptoms (chronic allergies) are most likely to occur from exposure to animal dander, house dust, or mold.
Review the Emergencies and Check Your Symptoms sections to determine if and when you need to see a doctor.
Health Tools
Health Tools help you make wise health decisions or take action to improve your health.
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Decision Points focus on key medical care decisions that are important to many health problems. |
| Should I have allergy shots for allergies to insect stings? | |
| Should I take allergy shots (immunotherapy) for allergic rhinitis and allergic asthma? | |
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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 shot | |
Emergencies
Do you have any of the following symptoms that require emergency treatment? Call 911 or other emergency services immediately.
- Shock:
- Moderate to severe difficulty breathing:
- Rapid swelling of the throat or tongue
- Swelling of the throat or tongue that causes difficulty breathing
- You had a severe reaction (anaphylaxis) in the past from the same type of sting, bite, food, or medicine (allergen), and similar symptoms are developing.
Note: Use an allergy kit prescribed by your doctor for your allergy problem if you have:
- Severe symptoms.
- A kit immediately available, and you have been taught how and when to use it.
- Had a severe reaction in the past from the same type of sting, bite, food, or medicine (allergen), and similar symptoms are developing.
Check Your Symptoms
If you answer yes to any of the following questions, click on the "Yes" in front of the question for information about how soon to see a health professional.
Review health risks that may increase the seriousness of your symptoms.
Have you used an epinephrine shot to treat an allergic reaction or been accidentally stuck with an epinephrine shot?
See significance of using or being accidentally stuck by an epinephrine shot if you need information to help you answer the questions below.
Review health risks that may increase the seriousness of your symptoms.
Call your health professional immediately if you answer "Yes" to any of the following questions.
| Note: |
If you have used an epinephrine shot to treat an allergic reaction or if you have been accidentally stuck with an epinephrine shot and you are not able to contact your doctor:
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Have you used an epinephrine shot to treat an allergic reaction?
Have you been accidentally stuck with an epinephrine shot?
If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
See significance of hives if you need information to help you answer the questions below.
Review health risks that may increase the seriousness of your symptoms.
Call your health professional immediately if you answer "Yes" to any of the following questions.
Have hives appeared suddenly (within the past 1 to 3 hours) and now cover all or most of your body?
Do you have swelling in your mouth or throat?
Call your health professional today if you answer "Yes" to the following question.
Do you have hives that appeared over several hours today and cover all or most of your body, but you are not having other symptoms?
You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to the following question.
Do you still have hives, without other symptoms, after 24 hours of home treatment?
If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
Do you have wheezing or difficulty breathing?
See significance of wheezing or difficulty breathing if you need information to help you answer the questions below.
Review health risks that may increase the seriousness of your symptoms.
Call your health professional immediately if you answer "Yes" to any of the following questions.
Is new mild difficulty breathing getting worse?
Do you feel short of breath, even when you are resting, but you can still speak in short sentences?
Call your health professional today if you answer "Yes" to the following question.
Do you have mild wheezing, even at rest, but you do not feel short of breath and can still speak in complete sentences?
You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to any of the following questions.
Have you had mild shortness of breath for the past 24 hours?
Have you had ongoing (chronic) mild breathing problems that have slowly gotten worse over the past 24 hours?
If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
See significance of new swelling if you need information to help you answer the questions below.
Review health risks that may increase the seriousness of your symptoms.
Call your health professional immediately if you answer "Yes" to any of the following questions.
Do you have swelling of your tongue or throat but you are not having breathing problems?
Is swelling near your lips or on your face causing mild breathing problems?
Do you have swelling of your face, eyelids, or ears?
Do you have swelling in your mouth or throat?
Call your health professional today if you answer "Yes" to any of the following questions.
Do you have major swelling across two large joints, such as from below the ankle to above the knee or from below the elbow to above the shoulder?
Do you have swelling of the palms of your hands or the soles of your feet?
You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to the following question.
Has swelling slowly gotten worse or not gotten better during the past 24 hours but you are not having any other problems?
If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
Do you have a rash and you are not sure if the rash was caused by an allergic reaction or a skin infection?
See significance of a skin infection if you need information to help you answer the questions below.
Review health risks that may increase the seriousness of your symptoms.
Call your health professional immediately if you answer "Yes" to any of the following questions.
Do you have peripheral arterial disease?
Do you have a disease or take a medicine that causes problems with your immune system?
Do you have red streaks extending from the rash?
Call your health professional today if you answer "Yes" to any of the following questions.
Do you have increased pain, swelling, redness, or warmth around a rash?
Is the area around your rash increasingly tender to the touch?
Do you have pus in or around the rash?
Do you know or think you have a fever?
You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to any of the following questions.
Have you had mild pain and swelling with redness less than 1 in. (2.5 cm) around a wound for 24 hours or longer?
Have you had painful, swollen glands (lymph nodes) near a wound for 24 hours or longer?
If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
See significance of a medicine if you need information to help you answer the question below.
Review health risks that may increase the seriousness of your symptoms.
Call your health professional today if you answer "Yes" to the following question.
Do you think your symptoms may be caused by a medicine?
| Note: |
If your answer is "Yes":
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If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
See significance of itching if you need information to help you answer the questions below.
Review health risks that may increase the seriousness of your symptoms.
Call your health professional today if you answer "Yes" to any of the following questions.
Is severe itching interfering with your usual activities or preventing sleep?
Do you have severe itching that is not improving after 12 hours of home treatment?
You may wait to see if the symptoms improve over the next 24 hours (or specified time period) if you answer "Yes" to any of the following questions.
Do you have moderate itching after 48 hours of home treatment?
Do you have mild, steady itching after 1 week of home treatment?
You need an appointment within the next 1 to 2 weeks if you answer "Yes" to the following question.
Have you had mild itching off and on for 4 weeks or longer?
If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
Do you think you have hay fever symptoms?
See significance of hay fever symptoms if you need information to help you answer the question below.
Review health risks that may increase the seriousness of your symptoms.
You need an appointment within the next 1 to 2 weeks if you answer "Yes" to the following question.
Do you have hay fever symptoms that have not gotten better after 2 weeks of home treatment? Hay fever symptoms can include:
- Itchy, watery eyes.
- Sneezing.
- Runny, stuffy, or itchy nose.
- Temporary loss of smell.
- Headache and fatigue.
- Dark circles under the eyes.
- Mucus draining from the nose down the back of the throat (postnasal drip).
If you have answered "No" to the above questions, go back to Check Your Symptoms and continue to answer the questions to evaluate your symptoms.
Other Symptoms to Watch For
Do you have any of the following symptoms?
- An insect bite or sting or spider bite: Go to the topic Insect Bites and Stings and Spider Bites.
- A tick bite: Go to the topic Tick Bites.
- A snake or lizard bite: Go to the topic Snake and Lizard Bites.
- A problem with an area of the body that has been pierced: Go to the topic Body Piercing Problems.
- A sinus infection, such as headache, facial pain, or fever: Go to the topic Facial Problems, Noninjury.
- Ear pain: Go to the topic Ear Problems and Injuries, Age 12 and Older or Ear Problems and Injuries, Age 11 and Younger.
- A cough that produces a lot of mucus: Go to the topic Coughs.
- Nosebleeds: Go to the topic Nosebleeds.
- Rash: Go to the topic Rash, Age 11 or Younger or Rash, Age 12 and Older.
If a visit to a health professional is not needed immediately, see the Home Treatment section for self-care information.
Home Treatment
For tips to help relieve symptoms of an allergic reaction, see home treatment for:
- A severe allergic reaction. If you have symptoms of a severe allergic reaction, call 911 or other emergency services immediately.
- Itching or hives. Avoid further contact with whatever you think is causing the hives.
- A sore throat caused by postnasal drip. Gargle with warm salt water to help ease throat soreness.
- Hay fever symptoms. Take an antihistamine to reduce symptoms of itchy, watery eyes; sneezing; or a runny, itchy nose. Be sure to read and follow any warnings on the label. Don't give antihistamines to your child unless you've checked with the doctor first.
- 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 as well as 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.
- Seasonal allergies. These are often caused by exposure to pollen.
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
Use the Check Your Symptoms section to evaluate your symptoms if any of the following occur during home treatment:
- Difficulty breathing, wheezing, or tightness in the chest develops.
- Swelling of the throat, tongue, lips or face develops.
- Hives develop or get worse.
- Swelling gets worse.
- A skin infection develops.
- Symptoms have not improved after 1 to 2 weeks of home treatment.
- Symptoms become more severe or more frequent.
Prevention
To prevent problems with severe allergic reactions:
- If you or your child have had a severe allergic reaction, talk to your doctor about getting a prescription for an allergy kit. Learn when and how to use it, and have it near you at all times. For more information, see:
- 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.
- 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. For more information, see:
- Discuss allergy shots (immunotherapy) with your doctor. Allergy shots may reduce your symptoms. For more information, see:
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. However, 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 as well as 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 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. Dander, urine, and dried saliva (especially from cats, but also from small animals such as mice and gerbils) are common allergens that can be spread throughout your home by indoor pets. Hair is often not the problem. If your allergies are severe, you may want to consider finding another home for your pet. Other alternatives include the following:
- Keep your pet out of your bedroom.
- Bath 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.
- 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.
Breast-feeding may prevent allergies. Breast-feed your baby for at least 6 months if possible to boost his or her immune system. Feeding only breast milk during the first 6 months of life may reduce the chances your child will develop food allergies or decrease the severity of your child's allergies. For more information, see the topic Breast-Feeding.
Preparing For Your Appointment
To 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?
- 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?
Other Places To Get Help
Organization
| MedicAlert Foundation International | |
| 2323 Colorado Avenue | |
| Turlock, California 95382 | |
| Phone: | 1-888-633-4298 (209) 668-3333 from outside the United States |
| Fax: | (209) 669-2450 |
| E-mail: | customer_service@medicalert.org |
| Web Address: | http://www.medicalert.org/home/Homegradient.aspx |
MedicAlert Foundation is a nonprofit organization that provides subscriber services for more than 4 million members worldwide. Services include providing identification jewelry listing the person's medical conditions and history and a computerized medical information database that is accessible 24 hours per day. As a member of MedicAlert, if medical care is needed, health professionals providing care can reach the person's complete medical history at any time. | |
Related Information
- Acute Bronchitis
- Allergic Rhinitis
- Asthma in Children
- Asthma in Teens and Adults
- Atopic Dermatitis
- Coughs
- Dry Skin and Itching
- Ear Problems and Injuries, Age 11 and Younger
- Ear Problems and Injuries, Age 12 and Older
- Facial Problems, Noninjury
- Influenza
- Insect Bites and Stings and Spider Bites
- Nosebleeds
- Pneumonia
- Poison Ivy, Oak, or Sumac
- Rash, Age 11 and Younger
- Rash, Age 12 and Older
- Respiratory Problems, Age 11 and Younger
- Respiratory Problems, Age 12 and Older
- Sinusitis
- Snake and Lizard Bites
- Sore Throat
- Strep Throat
- Stress Management
- Tattoo Problems
- Tick Bites
Credits
| Author | Sydney Youngerman-Cole, RN, BSN, RNC |
| Editor | Susan Van Houten, RN, BSN, MBA |
| Associate Editor | Tracy Landauer |
| Primary Medical Reviewer | William M. Green, MD - Emergency Medicine |
| Specialist Medical Reviewer | H. Michael O'Connor, MD - Emergency Medicine |
| Last Updated | July 11, 2007 |
