Allergies and colds both cause a runny nose, sneezing and congestion. The biggest clues are itchy eyes, fever and time: itchy, watery eyes are common with allergies but not with a cold, a cold is more likely to bring aches or a fever, and a cold usually clears within a week while allergies last as long as you’re around the trigger, according to Cleveland Clinic.
Get care right away for trouble breathing, chest pain or pressure that doesn’t go away, confusion, or bluish lips or face. MedlinePlus lists these as reasons to call 911 with COVID-19, and says any breathing problem with the flu is an emergency.
In the video above, family physician Dr. Richard Honaker explains that a cold usually makes you feel achy and unwell and may bring a fever, while allergies are mostly congestion: a runny nose, itchy eyes and stopped-up ears. He also talks about avoiding triggers and about the trade-off between older and newer antihistamines. For his allergy tips, see the video page. This article compares the symptoms in detail.
Allergies vs. cold vs. flu vs. COVID-19 vs. sinus infection
| Cold | Allergies | Flu | COVID-19 | Sinus infection | |
|---|---|---|---|---|---|
| Cause | A virus | Your immune system reacting to pollen, dust, pet dander or mold | Influenza viruses | The SARS-CoV-2 virus | Usually viruses; sometimes bacteria, fungi or allergies |
| How it starts | Gradually | When you’re around a trigger, often at the same time each year | Suddenly | 2 to 14 days after exposure, most often around day 5 | Can follow a cold or allergies |
| Fever | Low or none in adults; young children often 100°F to 102°F | Most people don’t get one | Common, often sudden, 100°F to 104°F; not everyone has one | Common | Can happen |
| Itchy eyes | Not as common | Common, with red, watery eyes | Not typical | Not listed as a main symptom | Not listed as a main symptom |
| Aches and tiredness | Muscle aches, headache | Tiredness possible; aches less likely | Body aches, chills, lack of energy | Body aches, tiredness, headache | Headache, facial pain |
| Nose | Runny or stuffy, sneezing | Sneezing, runny or stuffy, itchy nose | Runny or stuffy, sneezing | Stuffy or runny | Stuffy, thick yellow or green mucus |
| Sore throat, cough | Common | Possible | Common | Common | Post-nasal drip, cough |
| Other clues | Scratchy throat | Itchy mouth, throat or skin; clogged ears | Nausea, vomiting or diarrhea, more often in children | Loss of taste or smell; nausea, vomiting or loose stools | Facial pressure, tooth pain, bad breath or taste |
| How long | Most symptoms gone within a week | As long as the allergen is in the air; can be weeks or months | Most people better in 1 to 2 weeks; cough and tiredness can last weeks | Testing is the best way to tell it from flu | Acute: less than 4 weeks |
| Contagious? | Yes | No | Yes | Yes, even before symptoms | The infection itself isn’t, but the germs behind it can spread |
Sources for the table: Cleveland Clinic (allergic rhinitis, sinusitis, URI), MedlinePlus (common cold, allergic rhinitis, flu, COVID-19), MedlinePlus Magazine, and familydoctor.org. Symptoms overlap a lot, so use the table as a guide, not a diagnosis. Only a test can confirm flu or COVID-19.
Can allergies cause a fever?
Usually not. Cleveland Clinic says that despite the name, “hay fever” doesn’t usually cause a fever. A fever points more toward an infection, such as a cold, flu, COVID-19 or a sinus infection.
There’s one exception worth knowing in Texas. Cleveland Clinic says cedar fever, an allergy to mountain cedar pollen, can cause a low or mild fever, though most people with it don’t get one. Cleveland Clinic advises seeing a doctor for a sore throat with a fever, especially one over 100.4°F (38°C).
Does a cold make your eyes itch?
Not usually. Cleveland Clinic says itchy, red and watery eyes are common with allergies but not as common with a cold. MedlinePlus Magazine, from the National Library of Medicine, says itchy, watery eyes are not typical of colds or the flu. A cold can make your eyes watery, familydoctor.org notes, but itching is the stronger sign of allergies. Texas Children’s Hospital calls itchy or watery eyes “telltale signs” of an allergic reaction.
How long do allergies last vs. a cold?
- A cold usually goes away within a week, MedlinePlus says. People are most contagious in the first 2 to 3 days.
- Allergies stick around until the allergen is out of the air, Cleveland Clinic says. Some people have symptoms for weeks or months. Seasonal allergies flare when pollen is high, and year-round (perennial) allergies to things like dust mites, pet dander and cockroaches can last all year.
So symptoms that keep going well past a week without a fever, or that come back every pollen season, point toward allergies.
Cedar fever: a Texas winter allergy that feels like a cold
Many Texans get “cold” symptoms in the middle of winter that turn out to be allergies. Cleveland Clinic says cedar fever is an allergic reaction to pollen from mountain cedar (juniper) trees, and that central Texas has very high cedar pollen levels.
- When: Most common from about December to February, with a peak in mid-January. Symptoms can start in November and last through March (Cleveland Clinic). Texas Children’s Hospital says cedar pollen in Austin peaks from November to February.
- Symptoms: A stuffy or runny nose, itchy and watery eyes, sneezing, coughing or sore throat, tiredness, a partly lost sense of smell or taste, and sometimes a low fever. People with asthma may wheeze or feel short of breath.
- Why it’s confusing: Cleveland Clinic notes it happens during cold and flu season and shares symptoms with both. Skin or blood allergy tests can confirm a pollen allergy.
Texas Children’s Hospital also lists oak pollen into May, grass around May, ragweed from July to October, and mold all year in Austin, so allergy season in Texas never really ends.
What helps: allergies vs. a cold
For allergies, the first step is avoiding the trigger. Cleveland Clinic suggests limiting time outdoors when pollen is high, keeping windows closed, and washing clothes after being outside. Medicine options listed by MedlinePlus and Cleveland Clinic include:
- antihistamines (pills, nasal sprays or eye drops); some cause drowsiness
- corticosteroid nasal sprays, which MedlinePlus calls the most effective treatment
- decongestants, for short-term use only; nasal decongestant sprays can make stuffiness worse if used too long
- allergy shots or under-the-tongue tablets (immunotherapy) for hard-to-control allergies
For a cold, MedlinePlus recommends rest and fluids. Over-the-counter cold medicines may ease symptoms in adults and older children but don’t shorten a cold, and aren’t recommended for children under 4. Antibiotics don’t help a cold; see Antibiotics for an Upper Respiratory Infection.
Ask your doctor or pharmacist which medicine is right for you, and follow the label.
When to see a doctor
See a doctor if:
- cold symptoms get worse, or don’t improve after 7 to 10 days (MedlinePlus)
- you have a fever, a severe headache, or vision changes with sinus symptoms (MedlinePlus)
- allergy symptoms are severe, get in the way of daily life or sleep, or stop responding to treatment (MedlinePlus, Cleveland Clinic)
- you have new loss of taste or smell with a fever, which Texas Children’s Hospital calls a hallmark of COVID-19
- you have allergies and asthma, since hay fever can make asthma worse (Cleveland Clinic)
Cleveland Clinic says to go to the emergency room with a sinus infection for a high fever, confusion, vision changes (especially with eye pain or swelling), seizures or a stiff neck. Call 911 for the emergency signs at the top of this article.
Frequently asked questions
How can I tell if it’s allergies or a cold?
Look at three things: itchy eyes (more likely allergies), fever and body aches (more likely a cold), and how long it lasts (a cold usually clears within a week; allergies last as long as the trigger is around).
Can allergies cause a fever?
Usually not. Cleveland Clinic says most people with hay fever don’t get a fever. Cedar fever can sometimes cause a low fever, but most people with it don’t have one.
Does a cold make your eyes itch?
Not usually. Itchy, red, watery eyes are a stronger sign of allergies, Cleveland Clinic says.
Can allergies turn into a sinus infection?
MedlinePlus says sinusitis can follow allergies, as well as colds. Cleveland Clinic says allergies usually don’t cause the facial pain that a sinus infection does, so new facial pain or pressure is worth noting.
Is it allergies or COVID-19?
They can overlap. Fever and a new loss of taste or smell point to COVID-19, while itchy, watery eyes point to allergies, according to Texas Children’s Hospital. A COVID-19 test can tell you for sure.
Are allergies contagious?
No. Cleveland Clinic says hay fever isn’t contagious. Colds, flu and COVID-19 are. Wondering about a sore throat? See Is Strep Throat Viral or Bacterial?
Find a doctor: Dr. Richard Honaker, family medicine, Dallas-Fort Worth.
Sources
- Cleveland Clinic. Allergic Rhinitis (Hay Fever).
- Cleveland Clinic. Cedar Fever.
- Cleveland Clinic. Sinus Infection (Sinusitis).
- Cleveland Clinic. Upper Respiratory Infection (URI).
- Cleveland Clinic. Sore Throat (Pharyngitis).
- MedlinePlus (U.S. National Library of Medicine). Allergic rhinitis.
- MedlinePlus (U.S. National Library of Medicine). Common cold.
- MedlinePlus (U.S. National Library of Medicine). Flu.
- MedlinePlus (U.S. National Library of Medicine). COVID-19.
- MedlinePlus (U.S. National Library of Medicine). Sinusitis.
- NIH MedlinePlus Magazine. Achoo! Cold, flu, or something else? (2018).
- American Academy of Family Physicians, familydoctor.org. Colds and the Flu.
- Texas Children’s Hospital. Is this COVID or allergies?.
This article is for general information only and is not medical advice. Talk with a qualified health professional about your own situation. If you think you may have a medical emergency, call 911.
