Is It a Cold, Allergies or Infection? | Allergy & Asthma Center of Austin

How can you tell?

It is often difficult to tell the difference between allergies and infections since many of the symptoms are similar. Fever, sore throat, swollen glands, muscle aches and colored mucus do not occur with allergies and generally indicate an infection. Itching and sneezing, particularly during a season or with exposure to a particle like dust or mown grass, suggests an allergy. Stuffy nose, clear runny nose and watery eyes are common to both conditions.


Allergies are an unnecessary reaction to a harmless substance. Allergies occur in a genetically predisposed individual (run in families) and may involve the respiratory tract (hayfever, cedar fever, asthma), the skin (hives, eczema, poison ivy reactions), the gastrointestinal tract (vomiting, diarrhea, itchy mouth) or the whole body (allergic shock). For more detailed information about allergies see our Pollen Information page. Respiratory allergies often occur in a season (like the fall due to Ragweed pollen, the spring due to Oak pollen, or the winter due to Mountain Cedar pollen) or with exposure to something like dust, cats or mold. Allergies often cause sneezing, itching, watery nasal drip, stuffy nose, and watery, red, itchy eyes. These same symptoms can occur at the beginning of a cold (a viral respiratory infection). Allergy symptoms generally respond quickly to antihistamine and decongestant medications and can be prevented by prescription cortisone nasal sprays.


Colds are caused by infection with viruses. There are more than 300 viruses known to cause colds. Most children get between 4 and 12 colds per year and adults between 2 and 6. Cold symptoms can be nearly identical to allergy symptoms but systemic symptoms often accompany the nasal and eye symptoms. Fever is associated with about 20% of colds. Body aches, feeling tired all over or just feeling lousy is common with a cold. Sore throat, swollen glands, hoarseness and cough may also occur. Colds may begin abruptly and often spread among family members or coworkers. Colored mucus from the nose, throat or chest my also occur.

Unfortunately, colds do not respond to antibiotics.  Treating the symptoms of a cold and resting are the best approach.  Tylenol or ibuprofen help fever and aches, guiafenesin (over the counter Mucinex or Robitussin) can thin secretions, decongestants like Sudafed can decrease stuffiness and rinsing the nose with salt water can be soothing.  Most colds improve in 5-10 days.  Colds can be followed by bacterial infections in the sinus or middle ear.  Patients with asthma may worsen during or after a cold.

Though many of us refer to viral infections as 'flu', actual influenza is a more serious infection caused by influenza virus. Influenza is associated with higher, more prolonged fever, shaking chills and more significant body aches. While most colds resolve in 5-10 days, influenza may last 2 weeks and is more often associated with complications like pneumonia. Influenza is seasonal with peak incidence between January and March. Influenza immunization (flu shots) provide about 80% protection against infection. The formula for the flu shot is changed every year in an attempt to anticipate which flu strains will be more common each year. People over age 65 or younger people with chronic medical conditions like asthma should receive a flu shot every Fall in October or November. We have flu shots available for our patients in the fall.


Sinusitis is a bacterial infection of one or more of the sinus cavities located below, above and between the eyes. Sinusitis may occur following a cold or with nasal congestion due to allergies. Pain in the top teeth, above the eyes or in the cheeks, colored nasal mucus or post nasal drip and loss of sense of smell may occur. A cold lasting longer than 10 days may be a sinus infection. Unlike a viral cold, sinusitis responds to antibiotics as well as supportive care like decongestants, pain relievers and rinsing the nose with salt water.

So which is it?

Several clues may help distinguish a cold or sinusitis from allergies. Nasal symptoms associated with colored mucus that occur outside your usual allergy season are more likely an infection. If symptoms respond poorly to your usual allergy medicines and other family members are ill, suspect a cold. Laryngitis or significant cough is more common with infection than allergy. Though clues can help it is not always possible to know what is causing symptoms. If allergy medicines aren't helping it is reasonable to try treatment for infection. This may include Tylenol or ibuprofen for fever and discomfort, decongestants for stuffy nose, saline gargle or nasal rinse, rest, fluids and over the counter cough medicines like Delsym, Mucinex D or Robitussin DM. If symptoms are severe or last longer than 10 days, see your physician for consideration of treatment with an antibiotic.

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