Allergic reactions occur when the body defends itself against something that is not present. A normal immune system remembers and defends against invading bacteria and viruses. During allergic reactions, however, the immune system fights generally harmless allergens, such as pollen or mold, with production of a special class of antibody called immunoglobulin E (IgE).

Fast Facts

• Allergies are reactions of your immune system to one or more things.
• Pollens and mold spores can cause seasonal allergic reactions.
• The immune system is your body’s defense system. In most allergic reactions, however, it is responding to a false alarm.
• Allergies cause runny noses, sneezing, itching, rashes, swelling, hives, abdominal pain, or asthma. Allergies typically make you feel bad. However, a severe reaction, called anaphylaxis, is life threatening.

Each spring, summer, and fall, trees, weeds, and grasses release tiny pollen grains into the air. Some of the pollen ends up in your nose and throat. This can trigger a type of allergy called hay fever.

Symptoms can include

• Sneezing, often with a runny or clogged nose
• Coughing and postnasal drip
• Itching eyes, nose and throat
• Red and watery eyes
• Dark circles under the eyes

Your health care provider may diagnose hay fever based on a physical exam and your symptoms. Sometimes skin or blood tests are used. Taking medicines and using nasal sprays can relieve symptoms. You can also rinse out your nose, but be sure to use distilled or sterilized water with saline. Allergy shots can help make you less sensitive to pollen and provide long-term relief.

Trees, grasses, and weeds are often to blame

Ah, spring. It's the time of year when the cold starts to wane, and trees and flowers blossom.

But if you're one of the many people who suffer from seasonal allergies, those pretty trees and plants may make you feel worse, not better.

That's because of pollen, a powdery substance made by trees, weeds, and grasses.

Pollen is harmless, but if you have seasonal allergies, your body mistakes the pollen for something dangerous and tries to attack it. This reaction causes symptoms like coughing, a runny or stuffy nose, and itchy, watery eyes. You might feel like you have a cold.

Diagnosing seasonal allergies

Unlike colds, seasonal allergies usually last longer than a week or two. If you have some or all of these symptoms and are looking for relief, check with your health care provider.

Often, a skin test or allergen-specific blood test can help confirm which type of pollen you're allergic to. Providers can also diagnose seasonal allergies based on when your symptoms develop. For example:

• Tree pollen (especially from birches, oaks, elms, and maples) typically appears in spring.
• Grasses shed pollen in late spring and summer.
• Ragweed produces pollen in the fall.
• Mold spores often cause seasonal allergies during the spring, summer, and fall. They may also cause year-round allergies for people who live in buildings with too much moisture. Signs of excess moisture include high indoor humidity, water damage, or poor ventilation.

All in the family

Seasonal allergies often run in families. If both your parents or your siblings have them, you're more likely to suffer from them, too.

Many people with seasonal allergies also have asthma. They may experience shortness of breath, wheezing, and coughing, in addition to other symptoms.

Easing your symptoms

Although it's difficult to predict how bad an allergy season will be, paying attention to your local weather forecast can help. Here are some other useful tips:

• Stay indoors as much as possible on days with peak pollen counts.
• Save outdoor activities for late afternoon.
• Wear a face mask when you work outdoors.
• Close the windows and, if needed, use an air conditioner.
• Wear wraparound glasses to keep pollen out of your eyes.
• Keep the grass cut short and avoid gardening chores that may stir up allergens.
• Rinse off after being outside to remove pollen from your skin and hair.
• Brush off your pets after they’ve been outside to prevent allergens from coming inside with them.

Medication and other treatments

Your health care provider may suggest saline rinses to ease nasal congestion or antihistamines to relieve a runny nose, sneezing, and itchy eyes. Some antihistamines include decongestants, which can reduce congestion, but those medicines are not for everyone. Your provider may also suggest a nasal steroid spray.

For more serious cases, your health care provider may prescribe allergy shots. Over time, these injections can provide relief by reducing your immune system's reaction to a specific pollen or other allergen.

What is pollen?

Pollen is the grains or tiny seeds of flowering plants, trees, and grasses. These seeds can be carried on the wind and can cause various symptoms, or none at all, in individuals who are exposed to them.

What health problems can pollen cause?

For people with hay fever, also known as “allergic rhinitis,” breathing in pollen can cause sneezing, congestion, and a runny nose. Pollen exposure can also result in “allergic conjunctivitis” in some individuals, causing red, watery, or itchy eyes.

Pollen exposure can also cause asthma attacks in people who have asthma and for whom pollen is an asthma trigger.

How can I protect myself against pollen?

If you are allergic to pollen, or if you have asthma you can take steps to protect yourself:

• Check pollen forecasts on local news and online sources and plan to spend less time outdoors when pollen levels will be high.
• Take your allergy and/or asthma medications as prescribed by your health care provider.
• Don’t touch your eyes while you are outside, and wash your hands when you go back inside (before you touch your eyes).
• Shower after being outside to remove pollen from your skin and hair.
• Change your clothes after being outdoors.
• Keep windows closed during pollen season.
• Use high-efficiency filters in your home’s heating, ventilation, and air conditioning (HVAC) system. Make sure your HVAC system can use high-efficiency filters and that they don’t violate the system’s warranty.

How is climate change affecting pollen levels?

Our changing climate has caused shifts in precipitation patterns, more frost-free days, warmer seasonal air temperatures, and more carbon dioxide (CO₂) in the atmosphere. These changes can affect:

• when the pollen season starts and ends and how long it lasts each year,
• how much pollen plants create and how much is in the air, and
• how pollen affects human health.

Some of these changes in pollen due to climate change could have major impacts on human health such as increasing individuals’ exposure to pollen and their risk of having allergy and/or asthma symptoms.

Several types of pollen cause mild to severe seasonal respiratory allergy, including allergic rhinitis and asthma. But helpful defenses are available, according to researchers at the National Institute of Environmental Health Sciences (NIEHS).

Plant Pollen

Ragweed and other weeds, such as curly dock, lambs quarters, pigweed, plantain, sheep sorrel, and sagebrush are prolific producers of pollen allergens. Ragweed season runs from August to November, but pollen levels usually peak by mid-September in many areas in the country. Pollen counts are highest in the morning, and on dry, hot, windy days.

Protecting yourself

• Between 5:00 and 10:00 in the morning, stay indoors. Save outside activities for late afternoon or after a heavy rain, when pollen levels are lower.

• Keep windows in your home and car closed to lower exposure to pollen. Keep cool with air conditioners. Don’t use window or attic fans.

• Use a dryer, not a line outside; dry your clothes and avoid collecting pollen on them.

Grass Pollen

Grass pollens are regional as well as seasonal. Their levels also are affected by temperature, time of day, and rain. Only a small percentage of North America’s 1,200 grass species cause allergies, including:

• Bermuda grass
• Johnson grass
• Kentucky bluegrass
• Sweet vernal grass
• Timothy grass
• Orchard grass

Protecting yourself

• Have someone else mow your lawn. If you mow, wear a mask.

• Keep grass short.

• Grow ground covers that don’t produce much pollen, such as moss.

• Treat respiratory allergy with antihistamines, topical nasal steroids, cromolyn sodium, decongestants, or immunotherapy (see page 20 for details).

• Use an air purifier with high efficiency air filters (HEPA) or an electrostatic air filter.

Tree Pollen

Trees produce pollen earliest, as soon as January in the south, and as late as May and June in the northeast. They release huge amounts that can be distributed miles away. Fewer than 100 kinds of trees cause allergies. Some common ones are catalpa, elm, hickory, sycamore, and walnut.

Protecting yourself

• Plant species that do not aggravate allergies, such as crape myrtle, dogwood, fig, fir, palm, pear, plum, redbud, and redwood trees, or the female cultivars of ash, box elder, cottonwood, maple, palm, poplar, or willow trees.

Pollen is an airborne allergen that can affect our health. Pollen exposure can trigger various allergic reactions, including:

• Sneezing, runny nose, and congestion.
• Red, watery, or itchy eyes.
• Asthma or other respiratory illness exacerbation.

These symptoms have been linked to negative impacts on sleep, daily activities, productivity, concentration, and quality of life. Allergic asthma and seasonal allergies affect approximately 40% of the U.S. population.

For most people, hay fever is a seasonal problem—something to endure for a few weeks once or twice a year. But for others, such allergies can lead to more serious complications, including sinusitis and asthma.

• Sinusitis is one of the most commonly reported chronic diseases and costs almost $6 billion a year to manage. It is the inflammation or infection of the four pairs of cavities behind the nose. Congestion in them can lead to pressure and pain over the eyes, around the nose, or in the cheeks just above the teeth. Chronic sinusitis is associated with persistent inflammation and is often difficult to treat. Extended bouts of hay fever can increase the likelihood of chronic sinusitis. But only half of all people with chronic sinusitis are allergic.

• Asthma is a lung disease that narrows or blocks the airways. This causes wheezing, shortness of breath, coughing, and other breathing difficulties. Asthma attacks can be triggered by viral infections, cold air, exercise, anxiety, allergens, and other factors. Allergic asthma is responsible for almost 80 percent of all asthma diagnoses. It presents the same symptoms as nonallergic asthma, but differs in that it is set off primarily by an immune response to specific allergens. In most people with allergic asthma, the culprit allergens are those found indoors, such as pets, house dust mites, cockroaches and mold.

Knowing exactly what you are allergic to can help you lessen or prevent exposure and treat your reactions. There are several tests to pinpoint allergies:

• Allergy skin tests — Allergy skin testing is considered the most sensitive testing method and provides rapid results. The most common test is the “prick test,” which involves pricking the skin with the extract of a specific allergen, then observing the skin’s reaction.

• Serum-specific IgE antibody testing — These blood tests provide information similar to allergy skin testing.

For allergy sufferers, the best treatment is to avoid the offending allergens altogether. This may be possible if the allergen is a specific food, like peanuts, which can be cut out of the diet, but not when the very air we breathe is loaded with allergens, such as ragweed pollen. Air purifiers, filters, humidifiers, and conditioners provide varying degrees of relief, but none is 100 percent effective. Various over-the counter or prescription medications offer relief, too.

• Antihistamines. These medications counter the effects of histamine, the substance that makes eyes water and noses itch and causes sneezing during allergic reactions. Sleepiness was a problem with the first generation of antihistamines, but the newest drugs do not cause such a problem.

• Nasal steroids. These anti-inflammatory sprays help decrease inflammation, swelling, and mucus production. They work well in combination with antihistamines and, in low doses for brief periods of time, are relatively free of side effects.

• Cromolyn sodium. A nasal spray, cromolyn sodium can help stop hay fever, perhaps by blocking release of histamine and other symptom-producing chemicals. It has few side effects.

• Decongestants. Available in capsule and spray form, decongestants thin nasal secretions and can reduce swelling and sinus discomfort. Intended for short-term use, they are usually used in combination with antihistamines. Long-term usage of spray decongestants can actually make symptoms worse, while decongestant pills do not have this problem.

• Immunotherapy. Immunotherapy (allergy shots) might provide relief for patients who don’t find relief with antihistamines or nasal steroids. They alter the body’s immune response to allergens, thereby helping to prevent allergic reactions. Current immunotherapy treatments are limited because of potential side effects.

The pollen count is sky-high. You’re sneezing, your eyes are itching, and you feel miserable. Seasonal allergies are real diseases that can interfere with work, school or recreation. Allergies can also trigger or worsen asthma and lead to other health problems such as sinus infections (sinusitis) and ear infections, particularly in children.

An allergy is your body’s reaction to an otherwise innocent substance that it has identified as an invader. If you have allergies and encounter a trigger—called an “allergen”—your immune system fights it by releasing chemicals such as histamines (hence the term “antihistamines”). Histamines cause symptoms such as repetitive sneezing and itchy, watery eyes.

Allergy Medicines: Antihistamines and More

Seasonal allergies are usually caused by plant pollen, which can come from trees, weeds and grasses in the spring, and by ragweed and other weeds in late summer and early fall.

Since you can’t always stay indoors when pollen counts are high, your health care provider may recommend prescription or over-the-counter (OTC) medications to relieve symptoms. The U.S. Food and Drug Administration (FDA) regulates a number of medications that offer allergy relief.

Antihistamines reduce or block symptom-causing histamines and are available in many forms, including tablets and liquids. Many oral antihistamines are available over-the-counter and in generic form. Antihistamine nasal sprays are available by prescription only.

When choosing an OTC antihistamine, patients should read the Drug Facts label closely and follow dosing instructions, says Jenny Kelty, M.D., a pediatric pulmonologist at the FDA. Some antihistamines can cause drowsiness and interfere with the ability to drive or operate heavy machinery, like a car. There are other antihistamines that do not have this side effect; they are non-sedating. Non-sedating antihistamines are available OTC and by prescription.

Nasal corticosteroids are typically sprayed into the nose once or twice a day to treat inflammation and reduce allergy symptoms. Side effects may include stinging in the nose, nosebleeds, and growth effects in some children. Nasal corticosteroids are available OTC and by prescription.

Decongestants are drugs available both by prescription and OTC and come in oral and nasal spray forms. They are sometimes recommended in combination with antihistamines, which used alone do not have an effect on nasal congestion.

Drugs that contain pseudoephedrine are available without a prescription but are kept behind the pharmacy counter to prevent their use in making methamphetamine—a powerful, highly addictive stimulant often produced illegally in home laboratories. You will need to ask your pharmacist and show identification to purchase drugs that contain pseudoephedrine.

Using decongestant nose sprays and drops more than a few days may give you a “rebound” effect—your nasal congestion could get worse. These drugs are more useful for short-term use to relieve nasal congestion.

There are other medications for allergies that your doctor or healthcare provider may recommend that are prescription only. Talk to your doctor or healthcare provider to see if they may be right for you.

Immunotherapy is another option. One form of allergen immunotherapy is allergy shots in which your body responds to injected amounts of a particular allergen, given in gradually increasing doses, by developing immunity or tolerance to that allergen.

Patients can receive injections from a health care provider; a common course of treatment would begin with weekly injections for two to three months until the maximum dose is reached. After that, treatment could continue monthly for three to five years.

Another form of allergen immunotherapy involves administering the allergens in a tablet form under the tongue (sublingual) and is intended for daily use, before and during the pollen season. This type of immunotherapy is available only by prescription for the treatment of hay fever caused by certain pollens and have the potential for dialing down the immune response to allergens. However, they are not meant for immediate symptom relief, says Jay Slater, M.D., an allergist with the FDA. Sublingual therapy should start three to four months before allergy season. Although they are intended for at-home use, the first doses are to be taken in the presence of a health care provider

A Word about OTC Products and Kids

Always read the label before buying an OTC product for you or your children, says Kelty. “Some products can be used in children as young as 2 years of age, but others may have different dosing instructions for children less than 12 years of age.” Also, talk to your health care professional if your child needs to use nasal steroid spray for more than two months a year.

If you have an allergy, your immune system reacts to something that doesn’t bother most other people. People with seasonal allergies (also called hay fever or allergic rhinitis) react to pollen from plants. Symptoms may include sneezing, coughing, a runny or stuffy nose, and itching in the eyes, nose, mouth, and throat.

What the Science Says

Complementary approaches can be classified by their primary therapeutic input (how the therapy is taken in or delivered), which may be:

• Nutritional (e.g., special diets, dietary supplements, herbs, probiotics, and microbial-based therapies).
• Psychological (e.g., meditation, hypnosis, music therapies, relaxation therapies).
• Physical (e.g., acupuncture, massage, spinal manipulation).
• Combinations such as psychological and physical (e.g., yoga, tai chi, dance therapies, some forms of art therapy) or psychological and nutritional (e.g., mindful eating).

Nutritional approaches include what NCCIH previously categorized as natural products, whereas psychological and/or physical approaches include what was referred to as mind and body practices.

Many complementary health approaches have been studied for allergic rhinitis. There’s some evidence that a few may be helpful.

Psychological and Physical Approaches

• A 2015 evaluation of 13 studies of acupuncture for allergic rhinitis, involving a total of 2,365 participants, found evidence that this approach may be helpful.
• Rinsing the sinuses with a neti pot (a device that comes from the Ayurvedic tradition) or with other devices, such as nebulizers or spray, pump, or squirt bottles, may be a useful addition to conventional treatment for allergic rhinitis.

Nutritional Approaches

• A 2007 evaluation of six studies of the herb butterbur for allergic rhinitis, involving a total of 720 participants, indicated that butterbur may be helpful.

• Researchers have been investigating probiotics (live microorganisms that may have health benefits) for diseases of the immune system, including allergies. Although some studies have had promising results, the overall evidence on probiotics and allergic rhinitis is inconsistent. It’s possible that some types of probiotics might be helpful but that others are not.

• It’s been thought that eating honey might help to relieve pollen allergies because honey contains small amounts of pollen and might help people build up a tolerance to it. Another possibility is that honey could act as an antihistamine or anti-inflammatory agent. Only a few studies have examined the effects of honey in people with seasonal allergies, and their results have been inconsistent.

• Many other nutritional approaches have been studied for allergic rhinitis, including astragalus, capsaicin, grape seed extract, omega-3 fatty acids, Pycnogenol (French maritime pine bark extract), quercetin, spirulina, stinging nettle, and an herb used in Ayurvedic medicine called tinospora or guduchi. In all instances, the evidence is either inconsistent or too limited to show whether these products are helpful.

Side Effects and Risks

• People can get infections if they use neti pots or other nasal rinsing devices improperly. The U.S. Food and Drug Administration (FDA) has information on how to rinse your sinuses safely.

  • Most important is the source of water that is used with nasal rinsing devices. According to the FDA, tap water that is not filtered, treated, or processed in specific ways is not safe for use as a nasal rinse. Sterile water is safe; over-the-counter nasal rinsing products that contain sterile saline (salt water) are available.

  • Some tap water contains low levels of organisms, such as bacteria and protozoa, including amoebas, which may be safe to swallow because stomach acid kills them. But these organisms can stay alive in nasal passages and cause potentially serious infections. Improper use of neti pots may have caused two deaths in 2011 in Louisiana from a rare brain infection that the state health department linked to tap water contaminated with an amoeba called Naegleria fowleri.

• Acupuncture is generally considered safe when performed by an experienced practitioner using sterile needles. Improperly performed acupuncture can cause potentially serious side effects.

• Raw butterbur extracts contain pyrrolizidine alkaloids, which can cause liver damage and cancer. Extracts of butterbur that are almost completely free from these alkaloids are available. However, no studies have proven that the long-term use of butterbur products, including the reduced-alkaloid products, is safe.

• In healthy people, probiotics usually have only minor side effects, if any. However, in people with underlying health problems (for example, weakened immune systems), serious complications such as infections have occasionally been reported.

• Be cautious about using herbs or bee products for any purpose. Some herbs, such as chamomile and echinacea, may cause allergic reactions in people who are allergic to related plants. Also, people with pollen allergies may have allergic reactions to bee products, such as bee pollen, honey, royal jelly, and propolis (a hive sealant made by bees from plant resins). Children under 1 year of age should not eat honey.

• Talk to your health care provider about the best way to manage your seasonal allergies, especially if you’re considering or using a dietary supplement. Be aware that some supplements may interact with medications or other supplements or have side effects of their own. Keep in mind that most dietary supplements have not been tested in pregnant women, nursing mothers, or children.