How do you find out whether you’re allergic and what you’re allergic to?

A seasonal allergy can feel like a cold, with symptoms such as chronic congestion, a runny nose, and itchy, watery eyes. But allergies produce a thinner nasal discharge, won’t prompt a fever, are 14 times more likely than colds to trigger a migraine headache, and tend to last longer. If you’ve been sniffling for weeks on end, it’s probably time to get tested.

Luckily, that part is simple. The skin-prick test is the most common. A doctor introduces a number of allergens, sometimes as many as 60, by quickly pricking the patient’s arm or back. If redness, itching, or swelling occurs within 15 minutes, there’s an allergy match. “The process is so superficial, it’s quite painless,” says allergist Linda Cox. Alternatively, or if that test is inconclusive, a doctor might try a more sensitive intradermal shot, which injects allergens a little deeper below the skin.

What are the most effective treatments available?

Don’t be stoic. It’s important to seek relief from your symptoms, because without treatment, allergies may worsen over time. Allergic reactions can spread deep into the lungs, putting you at an increased risk for asthma. In fact, up to 40 percent of long-term allergy sufferers also have asthma. For more complicated reasons, another 40 percent of sufferers will develop sinusitis, an infection of the sinuses.

For mild to moderate allergies, drugs — some prescription, some over-the-counter — are usually enough. All work similarly, by trying to stop a reaction in its tracks. “The earlier you hit the medicine cabinet, the better your results,” says allergist Daniel Ein. You might want to take something before going outside, or consistently treat yourself before the start of the season. Here are the major drug categories.

Antihistamines

They prevent cells in the body from releasing histamines, which trigger the coldlike symptoms. Oral over-the-counter options are often combined with a decongestant (generally tagged with a D) for more relief.
Pros: Treat throat and nasal itching, watery eyes, a runny nose, and sneezing. Newer brands, like Claritin and Allegra, claim not to cause drowsiness.
Cons: Alone, they won’t help congestion or inflammation. Some brands can cause drowsiness.

Nasal Corticosteroids

Stronger than antihistamines, these prescription sprays, like Flonase, block inflammation and have been shown in some clinical studies to be the most effective remedy for allergy symptoms. (An oral version is available for extreme cases.)
Pros: Very effective at treating congestion.
Cons: May take a week or so to bring noticeable improvement. There’s also a higher risk of mild side effects — including nosebleeds, irritation, and a burning sensation — than with other allergy medications.

Decongestants

Nonprescription and fast acting, decongestants are available orally or as a nasal spray. They work by constricting blood vessels, which in turn reduces the amount of fluid leaked from the nose.
Pros: Instant relief from congestion.
Cons: Duration is temporary. While the nasal sprays, such as Afrin, act faster than oral alternatives, like Sudafed, most doctors discourage their use for more than three or four days because of their strong “rebound effect.” Basically, once you start, you’ll need more and more to get the same relief. Long-term use can produce chemical burns inside the nose.