An allergy is a reaction by your immune system to something that does not bother most other people. If you have an allergy, your immune system overreacts to a substance you inhaled, touched or ate.

What are the signs and symptoms of chronic allergies?

• Respiratory: itchy eyes, nose or throat; nasal congestion, runny nose, watery eyes, chest congestion, cough or wheezing
• Skin: itchiness or eczema
• Abdominal: vomiting or cramping and diarrhea consistently after eating certain foods

What are the most Substances that often cause reactions ?

• Pollen
• Dust mites
• Mold spores
• Pet dander
• Food
• Insect stings
• Medicines

Is this a seasonal allergies or common cold?

• Seasonal allergies or common cold can be so much alike that it is sometimes hard to tell the two apart. However, look closely and you can find clues about what is going on. Ask yourself these questions to help figure out if you have allergies or a cold:
  • Have the seasons changed? If yes, it could be allergies. Seasonal allergies come at the same time every year and around the same set of conditions (for example, when leaves start to fall in autumn or plants start to flower in spring). Allergy symptoms like sneezing, congestion, or a runny nose are the body's response to breathing in airborne allergens (like plant pollen or mold spores).
  • Colds, on the other hand, are caused by viruses that can turn up in any environment, at any time of year, but are most common in winter months.
  • Did symptoms come on suddenly? If yes, it may be seasonal allergies and the symptoms come on suddenly and last a long time. Cold symptoms tend to come on more gradually and usually go away within 7 to 10 days, but allergies last as long as someone is exposed to an allergen, which can be for weeks or months.
  • Do you have itchy, watery eyes? If yes, it could be allergies.
  • Is there a fever? If yes, it could be a cold. Allergy symptoms are never accompanied by a fever, while colds are sometimes. 

Allergy medications: Know your options

Several types of medications are used to treat allergy symptoms. Allergy medications are available as pills, liquids, inhalers, nasal sprays, eyedrops, skin creams and shots (injections). Some allergy medications are available over-the-counter, while others are available by prescription only. Here is a summary of the various types of allergy medications and why they are used.

1. Antihistamines block histamine, a symptom-causing chemical released by your immune system during an allergic reaction. Antihistamines that tend to cause drowsiness.
   • Antihistamine nasal sprays help relieve sneezing, itchy or runny nose, sinus congestion, and postnasal drip. Side effects of antihistamine nasal sprays may include a bitter taste, drowsiness or fatigue.
   • Antihistamine eye drops, available as over-the-counter or prescription medicines, can ease itchy, red, swollen eyes. These drops may have a combination of antihistamines and other medicines.
   • Side effects may include headache and dry eyes. If antihistamine drops sting or burn, try keeping them in the refrigerator or using refrigerated artificial-tear drops before you use the medicated drops.
2. Decongestants are used for quick, temporary relief of nasal and sinus congestion. They can cause insomnia, headache, increased blood pressure and irritability. They are not recommended for women who are pregnant or for people with high blood pressure, cardiovascular disease, glaucoma or hyperthyroidism.
   • Oral decongestants relieve nasal and sinus congestion caused by hay fever (allergic rhinitis).
   • Nasal decongestant sprays and drops relieve nasal and sinus congestion if they are used for a short period of time. Repeated use of these drugs for more than three consecutive days may result in a cycle of recurring or worsening congestion.
3. Corticosteroids relieve symptoms by suppressing allergy-related inflammation. Most of these medications require a prescription.
   • Corticosteroid sprays prevent and relieve stuffiness, sneezing and runny nose. Side effects can include an unpleasant smell or taste, nasal irritation and nosebleeds.
   • Inhaled corticosteroids are often used every day as part of treatment for asthma caused or complicated by reactions to airborne allergy triggers (allergens). Side effects are generally minor and can include mouth and throat irritation and oral yeast infections. Some inhalers combine corticosteroids with other asthma medications.
   • Corticosteroid eyedrops are used to relieve persistent itchy, red or watery eyes when other interventions aren't effective. A physician specializing in eye disorders (ophthalmologist) usually monitors the use of these drops because of the risk of vision impairment, cataracts, glaucoma and infection.
   • Oral corticosteroids are used to treat severe symptoms caused by all types of allergic reactions. Long-term use can cause cataracts, osteoporosis, muscle weakness, stomach ulcers, increased blood sugar (glucose) and delayed growth in children. Oral corticosteroids can also worsen hypertension.
   • Corticosteroid creams relieve allergic skin reactions such as itching, redness, scaling or other irritations. Some low-potency corticosteroid creams are available without a prescription, but talk to your doctor before using these drugs for more than a few weeks.
   • Side effects can include skin discoloration and irritation. Long-term use, especially of stronger prescription corticosteroids, can cause thinning of the skin and disruption of normal hormone levels.
4. Mast cell stabilizers block the release of immune system chemicals that contribute to allergic reactions. These drugs are generally safe but usually need to be used for several days to reach full effect. They are usually used when antihistamines are not working or not well-tolerated.
   • A leukotriene inhibitor is a prescription medication that blocks symptom-causing chemicals called leukotrienes. This oral medication relieves allergy signs and symptoms including nasal congestion, runny nose and sneezing.