Winter allergies or a cold?

Sneezing and a stuffy nose can come from a cold or from allergies, and NIH News in Health says colds, flu and allergies can be hard to tell apart because they share so many symptoms.¹ A few differences stand out: in its comparison, fever is rare with a cold and never comes with an airborne allergy, and an NIH expert says allergies can cause itchy, watery eyes, which people don’t normally have with a cold or flu.¹ Time matters too, since colds and flu rarely last beyond 2 weeks, while allergy symptoms usually last as long as a person is exposed to the allergen.¹ Our Cold or allergies? checklist takes these clues one at a time.

What a cold is

CDC describes a cold as a viral infection of the upper respiratory tract, also called an upper respiratory infection, or URI.³ More than 200 respiratory viruses can cause colds, and rhinoviruses are the most frequent cause in the United States.³ MedlinePlus says the viruses that cause colds are very contagious and can spread from person to person through the air and close personal contact.⁸

The signs and symptoms of a cold usually peak within 2 to 3 days of infection, CDC says.³ Its list includes a runny nose, nasal congestion, cough, sneezing, sore throat, headache, mild body aches and fever, which it says is usually low grade in older children and adults.³ Colds usually last less than a week.³ CDC’s fact sheet on colds adds that most people with colds do not have fever, and that some symptoms, especially a runny nose and cough, can last up to 10 to 14 days.⁵

What sets allergies apart

When people with allergies breathe in things like pollen or pet dander, the immune cells in the nose and airways may overreact to these harmless substances, NIH News in Health explains.¹ ACAAI says hay fever shares many of the same symptoms as a common cold but is not caused by a virus or bacteria and is not contagious.¹⁰

In ACAAI’s description, symptoms of seasonal allergic rhinitis can occur in spring, summer and early fall and are usually caused by airborne mold spores or pollen from trees, grass and weeds.¹⁰ People with perennial allergic rhinitis have symptoms year-round, generally caused by dust mites, pet hair or dander, cockroaches or mold.¹⁰

Why winter makes it harder to tell

The AAAAI calls cold weather a prime time for stuffy noses, sore throats and watery, itchy eyes.⁹ Colds are more common in the winter and spring, MedlinePlus says, though people can get them at any time.⁸ In the United States, flu season usually occurs in the fall and winter, and most of the time flu activity peaks between December and February.⁶ CDC notes that many respiratory viruses, like influenza virus and RSV, usually circulate during winter, and that the viruses behind COVID-19, flu and RSV can cause cold-like symptoms but do not cause colds.³

Indoor allergies add to the mix: ACAAI says they are a year-round problem but are noticed more during the winter because people spend more time at home.¹² With doors and windows shut against the cold, it says, allergens are sealed indoors and the heating system recirculates the indoor air and any allergy triggers.¹² It says dust, mold, pet dander, and dust mite and cockroach droppings can hide anywhere and cause sneezing, coughing and congestion.¹² Our guide to allergies at home in winter covers these indoor allergens in more detail.

Cedar fever in Texas

The Texas A&M Forest Service says the pollination period of mountain cedar falls in the middle of cold and flu season.¹⁴ The trees typically begin producing pollen in mid-December, and production peaks in mid-January before slowly tapering off toward the beginning of March.¹⁴ The Forest Service says it’s not uncommon for people with cedar fever to mistake their symptoms for a cold or the seasonal flu.¹⁴ Cedar fever isn’t a flu or a virus: it is an allergic reaction to the pollen released by mountain cedar trees.¹⁵

On fever, ACAAI says hay fever doesn’t cause one.¹⁰ The Forest Service puts it differently for cedar fever: it says some people do run a slight fever, but that if a fever is higher than 101.5°F, pollen likely isn’t the cause.¹⁴

Clues that point one way or the other

Some symptoms don’t separate the two: NIH’s table lists sneezing as usual, and a stuffy, runny nose as common, with both a cold and an airborne allergy, and fatigue or weakness as happening sometimes with either.¹ The AAAAI sets colds and allergies side by side like this:

Clue	Colds	Allergies
Symptoms	Similar to allergies, but may also include sore throat, fever and body aches	Runny or stuffy nose, sneezing, wheezing, itchy nose, watery or itchy eyes
Warning time	Develops over several days	Begins shortly after exposure to an allergen
How long it lasts	Should clear up within several days	Lasts as long as exposure

Everything in this table comes from the AAAAI’s page on colds, allergies and sinusitis.⁹ The same page says that symptoms that last more than a week, or that seem to turn off and on based on surroundings, may mean allergies or sinusitis.⁹

Itching is another clue: NIH News in Health says itchy eyes, nose or ears could also be an allergy, and that allergy symptoms tend to stop when a person is no longer exposed to the cause.² In an ACAAI resource, allergist Mitchell H. Grayson, MD, says people with allergies tend to have symptoms at the same time every year, and that a fever probably means a cold or flu.¹¹

NIH News in Health says flu can cause a high fever that lasts 3 to 4 days, along with a headache, fatigue and general aches and pain, which are less common with a cold.¹ CDC says flu symptoms usually come on suddenly, and notes that not everyone with flu will have a fever.⁷ The allergy symptom quiz looks at when and where symptoms happen and points to likely triggers.

When sources say to get care

On its page about managing colds, CDC says to seek medical care for anyone with trouble breathing or fast breathing, dehydration, a fever that lasts longer than 4 days, symptoms that last more than 10 days without getting better, symptoms such as fever or cough that improve then return or worsen, or chronic medical conditions that get worse.⁴ CDC says this list is not all-inclusive, and to see a healthcare provider for any symptom that is severe or concerning.⁴ It also says that people with symptoms of a respiratory virus who are at higher risk of severe illness from COVID-19 or flu should contact a healthcare provider right away, even if the illness is mild.⁴ CDC’s cold fact sheet says to talk to a healthcare professional right away if a child under 3 months old has a fever of 100.4°F (38°C) or higher.⁵

For flu, CDC gives separate lists of emergency warning signs in children and adults that call for medical care right away, and says the lists are not all inclusive.⁷ In adults, the signs include difficulty breathing or shortness of breath and persistent pain or pressure in the chest or abdomen.⁷

For allergies, ACAAI says to see an allergist if a person has hay fever or other allergy symptoms several months out of the year, or if asthma or allergies interfere with day-to-day activities or decrease quality of life, among other reasons.¹³ For questions about symptoms that come back every winter, talk to an allergist.