Is it asthma? Or allergies?

They can make you miserable — that’s one thing allergies and asthma have in common. The two often occur together: Almost 19 million adults in the USA have asthma, statistics show, and more than half have the type that’s induced by allergies. That means the ragweed pollen that’s currently sending some people’s seasonal allergies into overdrive, for example, can also lead to asthma symptoms.

But while allergens are at the root of all allergic reactions, the same is not true for asthma. Allergies occur when your immune system overreacts to certain substances, such as pollen, dust mites, mold, particular foods or bug bites. Asthma attacks can be triggered by different factors, such as stress, exercise or cold weather.

Here are three more ways they differ:

Asthma affects only the airways. Regardless of the trigger, the resulting attack is the same: an inflammation and narrowing of air passages, which reduces airflow to the lungs. The location of an allergic reaction depends on the allergen. If it’s airborne and inhaled (like mold spores), it most likely will affect the eyes, nose and lungs. If it’s ingested, it may affect your mouth or stomach; a bug bite or latex allergy could cause a skin reaction.

One wheezes; the other sneezes. The four hallmarks of asthma are chest tightness, shortness of breath, coughing and a squeaky exhale called wheezing. Allergy symptoms vary: Hay fever, for example, is characterized by congestion, sneezing, runny nose and watery eyes. Reactions to food may include a tingling mouth, swollen lips or tongue, and nausea; bug bite allergies can cause hives and swelling.

Asthma requires control. It’s a chronic condition with no cure, so treatment focuses on control. But for people who experience asthma symptoms more than twice a week, daily controller medications are necessary. Surprisingly, a recent survey of 1,000 asthma sufferers found that about half of people with persistent asthma are not using controller meds. Poor asthma control reduces quality of life and raises your risk of complications. For allergies, focus on prevention: Your doctor can help you identify and avoid triggers, and that may be enough to prevent allergic reactions. For more severe symptoms, medications and allergy shots are also available.