What is the difference between a cold flu and allergies

Cold, Flu, or Allergy?

Know the Difference for Best Treatment

You’re feeling beautiful lousy. You’ve got sniffles, sneezing, and a sore throat. Is it a freezing, flu, or allergies? It can be hard to tell them apart because they share so numerous symptoms.

What is the difference between a freezing flu and allergies

But understanding the differences will assist you select the best treatment.

“If you know what you own, you won’t take medications that you don’t need, that aren’t effective, or that might even make your symptoms worse,” says NIH’s Dr. Teresa Hauguel, an expert on infectious diseases that affect breathing.

Cold, flu, and allergy every affect your respiratory systemThe body parts that assist you breathe, including your nose, throat, and lungs., which can make it hard to breathe. Each condition has key symptoms that set them apart.

Colds and flu are caused by diverse viruses.

“As a law of thumb, the symptoms associated with the flu are more severe,” says Hauguel. Both illnesses can lead to a runny, stuffy nose; congestion; cough; and sore throat. But the flu can also cause high fever that lasts for 3-4 days, along with a headache, fatigue, and general aches and pain. These symptoms are less common when you own a cold.

“Allergies are a little diverse, because they aren’t caused by a virus,” Hauguel explains.

“Instead, it’s your body’s immune systemProtects your body from invading germs and other microscopic threats. reacting to a trigger, or allergen, which is something you’re allergic to.” If you own allergies and breathe in things love pollen or pet dander, the immune cells in your nose and airways may overreact to these harmless substances. Your delicate respiratory tissues may then swell, and your nose may become stuffed up or runny.

“Allergies can also cause itchy, watery eyes, which you don’t normally own with a freezing or flu,” Hauguel adds.

Allergy symptoms generally final as endless as you’re exposed to the allergen, which may be about 6 weeks during pollen seasons in the spring, summer, or drop.

Colds and flu rarely final beyond 2 weeks.

Most people with a freezing or flu recover on their own without medical care. But check with a health care provider if symptoms final beyond 10 days or if symptoms aren’t relieved by over-the-counter medicines. For more about when to see a doctor, go to CDC’s Flu Page.

To treat colds or flu, get plenty of relax and drink lots of fluids. If you own the flu, pain relievers such as aspirin, acetaminophen, or ibuprofen can reduce fever or aches.

Allergies can be treated with antihistamines or decongestants. See the “Wise Choices” box for more details.

Be careful to avoid “drug overlap” when taking medicines that list 2 or more athletic ingredients on the label. For example, if you take 2 diverse drugs that contain acetaminophen—one for a stuffy nose and the other for headache—you may be getting too much acetaminophen.

“Read medicine labels carefully—the warnings, side effects, dosages. If you own questions, talk to your doctor or pharmacist, especially if you own children who are sick,” Hauguel says.

“You don’t desire to overmedicate, and you don’t desire to risk taking a medication that may interact with another.”

Symptoms Cold Flu Airborne Allergy
Fever Rare Usual, high (100-102 °F), sometimes higher, especially in young children); lasts 3-4 days Never
Headache Uncommon Common Uncommon
General Aches, Pains Slight Usual; often severe Never
Fatigue, Weakness Sometimes Usual, can final up to 3 weeks Sometimes
Extreme Exhaustion Never Usual, at the beginning of the illness Never
Stuffy, Runny Nose Common Sometimes Common
Sneezing Usual Sometimes Usual
Sore Throat Common Sometimes Sometimes
Cough Common Common, can become severe Sometimes
Chest Discomfort Mild to moderate Common Rare, except for those with allergic asthma
Treatment Get plenty of rest.
Stay hydrated.

(Drink plenty of fluids.)
Aspirin (ages 18 and up), acetaminophen, or ibuprofen for aches and pains

Get plenty of rest.
Stay hydrated.
Aspirin (ages 18 and up), acetaminophen, or ibuprofen for aches, pains, and fever
Antiviral medicines (see your doctor)
Avoid allergens (things that you’re allergic to)
Nasal steroids
Prevention Wash your hands often.
Avoid shut contact with anyone who has a cold.
Get the flu vaccine each year.
Wash your hands often.
Avoid shut contact with anyone who has the flu.
Avoid allergens, such as pollen, home dust mites, mold, pet dander, cockroaches.
Complications Sinus infection middle ear infection, asthma Bronchitis, pneumonia; can be life-threatening Sinus infection, middle ear infection, asthma

Do you own a Freezing, the Flu, or Allergies?

The above table details the symptom differences between every three conditions.

The common symptoms of a freezing, flu and allergies are a stuffy or a runny nose, sneezing, a sore throat, a cough, a headache, or even fatigue.

Two differing symptoms are a fever or aches/pain, these would not be caused by allergies, but could be due to a freezing or the flu. Symptoms of the flu are often more severe than a cold.

While the symptoms are similar, the origin of the conditions are diverse. A freezing and the flu are both caused by diverse viruses, whereas allergies are caused by your immune system reacting to a trigger. Common inhalant allergy triggers are pollen, dust, mold, pet dander.

See related: Is it a cold?

Or is it Allergies?


Another key difference is when and how often patients own these conditions. A freezing can be caught 3 or 4 times a year, where as patients are likely only to get the flu once. Allergies are a whole diverse tale, allergies reccur seasonally and repeatedly.

Since external triggers cause allergies, what you are allergic to determines when you start to feel these symptoms. Those who are allergic to grass and trees are more likely to suffer in the spring, whereas ragweed pollen affects allergy sufferers in the drop.

Those who own indoor triggers, love dust, mold, or pet dander, may experience symptoms year circular when they are in contact with the allergy trigger.


No one likes getting ill, for common freezing prevention patients should practice excellent handwashing habits, avoid people who own a freezing and avoid spreading germs. The CDC recommends everyone over 6 months of age get the influenza vaccine. Allergy symptoms can be prevented by controlling your environment and avoiding triggers when possible.


If you own a freezing, we recommend relax, drink lots of fluids, and treat your symptoms until they subside.

If you own the flu, you can get an antiviral drug 24-48 hours after you’ve begun experiencing symptoms. Allergies are treated with avoidance methods, medication to control the symptoms, and allergy shots to treat the cause.

Understanding the differences between these conditions can assist you get the treatment you need quickly. If your symptoms return at the same time every year, you may own allergies. Talk to your doctor, or schedule an appointment with one of our board-certified allergists today.

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Allegra and Zyrtec are both antihistamines, but is one more effective or less likely to cause sedation than the other?

Allegra has the lowest risk of sedation out of every antihistamines so is preferred if an antihistamine is needed for people working in safety-critical jobs.

Even though Zyrtec is 3.5 times more likely to cause sedation than Allegra, it is still much less sedating than some older antihistamines such as promethazine.

Other differences:

  1. Several studies own found cetirizine (Zyrtec) to be more effective than fexofenadine (Allegra) at relieving symptoms of allergic rhinitis and urticaria, and it appears to own a longer duration of action.
  2. Allegra works within two hours and Zyrtec works within one hour.
  3. Allegra should not be taken with grapefruit juice.

    Zyrtec has no reported food interactions.

  4. Studies own not compared the effects of Allegra and Zyrtec for conditions such as postnasal drip, but research suggests intranasal antihistamines such as azelastine are more effective.
  5. Zyrtec and Allegra should not be taken at the same time, instead, if symptoms are persisting, it is better to take another drug with a diverse mechanism of action.

Allegra is a brand name for the drug fexofenadine and Zyrtec is a brand name for the drug cetirizine. Both fexofenadine and cetirizine are favorite antihistamines with numerous similarities but there are some significant differences.

Which is more sedating?

Allegra or Zyrtec?

Allegra (fexofenadine) and Zyrtec (cetirizine) are second-generation antihistamines. Second-generation antihistamines were first developed in the 1990s to provide allergy relief without the unwanted side effect of sedation common to first-generation antihistamines such as promethazine and diphenhydramine.

What is the difference between a freezing flu and allergies

However, it soon became apparent that not every second-generation antihistamines were equal when it came to not causing drowsiness or affecting other thought processes. Cetirizine is significantly more likely than fexofenadine to cause drowsiness.

Fexofenadine (Allegra), even in dosages exceeding those recommended, is the least sedating of every second-generation antihistamines, so is considered the antihistamine of choice for people in safety-critical jobs such as airline pilots.

Which is more effective for Allergic rhinitis?

Trials own shown both Allegra (fexofenadine) and Zyrtec (cetirizine) are significantly more effective than placebo (a pretend pill) for reducing symptoms associated with allergic rhinitis, hay fever, and other allergies.

Trials own not consistently shown that one antihistamine is more effective than another; however, one trial reported cetirizine produced a 26% greater reduction in the number of allergic rhinitis symptoms at 12 hours and 14% greater reduction in symptoms overall compared with fexofenadine. Cetirizine also appeared more effective for symptoms such as runny nose, sneezing, itchy/watery eyes, and itchy nose, mouth or throat. Cetirizine was slightly more likely (0.8%) than fexofenadine to cause drowsiness.

Another trial reported similar findings (33% greater reduction in allergic rhinitis symptoms) and also found cetirizine had a longer duration of effect.

Intranasal or ophthalmic (into the eye) antihistamines own a quicker onset of action than oral antihistamines (within about 15 minutes); however, they need to be istered several times daily. In people with allergic rhinoconjunctivitis and predominantly eye symptoms, ophthalmic antihistamines work much quicker (within 3 to 15 minutes) and are much more effective than any other form of treatment.

Intranasal antihistamines are as effective as intranasal cromolyn, intranasal nedocromil, and leukotriene modifiers in seasonal allergic rhinitis; however, are not as effective at relieving nasal congestion and other symptoms as intranasal glucocorticoids.

Allegra Vs Zyrtec for urticaria and other skin reactions

All second generation antihistamines, including Allegra and Zyrtec, are effective for acute and chronic urticaria, although more trials own been conducted in people with chronic urticaria.

What is the difference between a freezing flu and allergies

One trial found cetirizine to be more effective than fexofenadine at relieving symptoms in 97 patients with chronic urticaria with 51.9% of participants taking cetirizine reporting themselves as symptom-free after 28 days of treatment compared with only 4.4% of participants taking fexofenadine. Partial improvement was reported by 36.5% of people assigned cetirizine (42.2% assigned fexofenadine) and 11.5% experienced no improvement with cetirizine (53.3% with fexofenadine). No difference in side effects was noted between the two.

Allegra Vs Zyrtec for Postnasal Drip

Post nasal drip may happen for various reasons — allergies (particularly to dairy), colds or flu, various drugs (including birth control pills and high blood pressure tablets), freezing temperatures, bright lights, hormonal changes and spicy foods.

Thin postnasal drip secretions caused by allergies may be treated with antihistamines.

Second-generation antihistamines such as Allegra and Zyrtec may offer better relief than older-type antihistamines such as promethazine (older antihistamines tend to thicken post-nasal secretions). Intranasal antihistamines, such as azelastine, own a faster onset of action (15 minutes) and appear more effective than oral antihistamines although require more frequent istration. Other treatments include decongestants, cromolyn, and corticosteroid nasal sprays.

In the treatment of post nasal drip caused by nonallergic causes, oral second-generation antihistamines are not extremely effective.

However, the intranasal antihistamine azelastine is effective. Azelastine improves every rhinitis symptoms including nasal congestion, postnasal drip, sneezing and sleeping difficulty. The most common side effect is a metallic aftertaste; however, this is more likely at higher dosages and tends to dissipate with continued use.

Allegra Vs Zyrtec To Relieve Freezing Symptoms

Second-generation antihistamines (such as Allegra and Zyrtec) own limited effectiveness at relieving symptoms of freezing such as a runny nose and sneezing (only 45% of adults felt better after using them compared to 35% with placebo [a pretend pill]).

Effects were only noticeable if used within the first two days of a freezing, use of antihistamines made no difference thereafter.

Allegra Vs Zyrtec: istration

The antihistamine effects of Allegra and Zyrtec final for at least 24 hours, therefore, they are both given once daily. Fexofenadine, the athletic ingredient of Allegra works within two hours. Cetirizine, the athletic ingredient of Zyrtec works within one hour.

Allegra Vs Zyrtec: Side Effects, Interactions and Price

Side effects are generally mild with second-generation antihistamines and include a headache and rarely dry mouth, and nausea.

Zyrtec is 3.5 times more likely than Allegra to cause sedation; however, Zyrtec is still much less sedating than older antihistamines such as promethazine.

Side effects are generally mild with second-generation antihistamines and include a headache and rarely dry mouth, and nausea.

What is the difference between a freezing flu and allergies

Every the second generation antihistamines currently on the market appear free from adverse cardiovascular effects. Few major interactions own been reported with either Allegra or Zyrtec; however, there is the possibility that side effects such as sedation, confusion, and mental alertness may be enhanced if given with other drugs with this side effect.

Grapefruit juice appears to decrease the rate and extent of absorption of fexofenadine (Allegra) by about 30%. Cetirizine (Zyrtec) has no reported interactions with grapefruit or grapefruit products. More studies are needed to determine if there are any interactions between second generation antihistamines and herbal products and other types of food.

Always speak with your doctor of pharmacist before using any drugs in combination.

Cost is similar for 30 Allegra and 30 Zyrtec tablets and both are available as generics.

See also:Drugs.com Compare Tool — Allegra vs Zyrtec


  1. Post-Nasal Drip. American Academy of Otolaryngology — Head and Neck Surgery. http://www.entnet.org/content/post-nasal-drip
  2. Simon FER, Simons KJ. H1 Antihistamines: Current Status and Future Directions.

    The World Allergy Organization Journal. 2008;1(9):145-155. doi:10.1186/1939-4551-1-9-145.

  3. Meltzer EO, Caballero F, Fromer LM, Krouse JH, Scadding G. Treatment of congestion in upper respiratory diseases. International Journal of General Medicine. 2010;3:69-91.
  4. Day JH1, Briscoe MP, Rafeiro E, et al. Comparative efficacy of cetirizine and fexofenadine for seasonal allergic rhinitis, 5-12 hours postdose, in the environmental exposure unit.

    Allergy Asthma Proc. 2005 Jul-Aug;26(4):275-82.

  5. Handa S, Dogra S, Kumar B. Comparative efficacy of cetirizine and fexofenadine in the treatment of chronic idiopathic urticaria.J Dermatolog Treat. 2004 Jan;15(1):55-7.
  6. Mann RD, Pearce GL, Dunn N, Shakir S. Sedation with “non-sedating” antihistamines: four prescription-event monitoring studies in general practice. BMJ?: British Medical Journal. 2000;320(7243):1184-1187.
  7. Banfield C, Gupta S, Marino M, et al.

    Grapefruit juice reduces the oral bioavailability of fexofenadine but not desloratadine. Clin Pharmacokinet. 2002;41(4):311-8.

  8. Slater JW1, Zechnich AD, Haxby DG.Second-generation antihistamines: a comparative review.Drugs. 1999 Jan;57(1):31-47. http://www.ncbi.nlm.nih.gov/pubmed/9951950
  9. Sharma M, Bennett C, Cohen SN, Carter B. H1-antihistamines for chronic spontaneous urticaria. Cochrane Database of Systematic Reviews 2014, Issue 11.

    Art. No.: CD006137. DOI: 10.1002/14651858.CD006137.pub2

  10. Hampel F, Ratner P, Mansfield L, et al. Fexofenadine hydrochloride, 180 mg, exhibits equivalent efficacy to cetirizine, 10 mg, with less drowsiness in patients with moderate-to-severe seasonal allergic rhinitis. Ann Allergy Asthma Immunol. 2003 Oct;91(4):354-61.

How numerous times own you dismissed sniffles as "just a cold," and carried on with a stuffed nose and sinuses assuming that the symptoms would eventually run their course, perhaps a bit more quickly with a few doses of Mom’s homemade chicken soup?

Influenza is another tale.

The common freezing eventually fizzles, but the flu may be deadly. Some 200,000 people in the U.S. are hospitalized and 36,000 die each year from flu complications — and that pales in comparison to the flu pandemic of 1918 that claimed between 20 and 100 million lives. The best defense against it: a vaccine. Yet barely 30 percent of 4,000 U.S. adults surveyed said they’d been inoculated this season, despite a record supply of flu shots, according to a new RAND Corp. survey. (GlaxoSmithKline, which makes flu vaccine, helped pay for the survey.)

So what is the difference between a freezing and the flu – and how can you be certain which one you have?

We asked Jonathan Field, director of the allergy and asthma clinic at N.Y.U.

Langone Medical Center/Bellevue Hospital in New York. Following is an edited transcript of our interview with him.

What causes the flu? How is it diverse from a cold?

The flu is a viral infection caused by the influenza virus, a respiratory virus. The common freezing is also a viral infection caused by the adenovirus or coronavirus and there are numerous, numerous subsets with a lot of variability. That’s why it’s said there’s no cure for the common freezing [and] there’s no genuine vaccine. The flu is known to be from influenza and is preventable with vaccination.

Colds tend to produce runny nose, congestion, sore throat. Influenza is more pronounced in that it infects the lungs, the joints and causes pneumonia, respiratory failure and even death. It tends to infect the intestinal tract more in kids, with diarrhea and vomiting. Because of the relative immaturity of the gut, they may absorb more virus and that wreaks more havoc on the intestines. Flu causes epidemics and pandemics with the potential for mortality, whereas the common freezing is a nuisance for us.

How can someone who’s feeling ill distinguish between freezing and flu, or an allergy?

Flu typically starts in early November and can go until March.

The peak time is now — November to January. Allergy is typical in spring or drop, and freezing more so in winter.

The body can reply in only so numerous ways, but there are things you can use to differentiate.

What is the difference between a freezing flu and allergies

Allergic symptoms are similar to those of a freezing, but [result from] your immune system responding to something benign. Generally there’s no fever, and there’s an allergic manifestation of itch in the back of the throat or the ears. It’s unlikely with allergy to own body aches. With a freezing, there’s sometimes a low-grade fever.

You can tell the difference by the length and severity of the illness and whether you’ve had a similar experience in the past. Both colds and flu generally final the same seven to 10 days, but flu can go three to four weeks; the flu virus may not still be there, but you own symptoms endless after it’s left.

Allergy can final weeks or months.

Are the treatments for these illnesses different?

For any of these things, if it affects the nose or sinus, just rinsing with saline that gets the mucus and virus out is a first-line defense. It’s not the most pleasant thing to do, but it works extremely well.

What is the difference between a freezing flu and allergies

There are classes of medicines that can assist the flu — Tamiflu and Relenza — antivirals that block viruses’ ability to reproduce and shorten the length and severity of the illness. But they own to be taken within 48 hours or the cat is proverbially out if the bag [because by then] the virus has done the most of its reproduction. For a freezing or flu, relax and use decongestants and antihistamines, ibuprofen, acetaminophen, chicken soup and fluids.

Zinc supposedly helps the body’s natural defenses work to their natural capacity and decrease the severity and length of a freezing. Cells need zinc as a catalyst in their protective processes, so if you supply them with zinc, it helps them work more efficiently.

You should also withhold iron supplements. Viruses use iron as part of their reproductive cycle, so depriving them of it blocks their dissemination.

The majority of these infections are not bacterial and do not require [nor will they reply to] antibiotics. My law of thumb is that a viral infection should go away in seven to 10 days. If symptoms persist after that, you’d consider if it’s bacteria love Strep or Haemophilus influenzae.

Those bacteria cause illnesses that are longer lasting.

Is that treatment approach the same for kids?

In general, the same rules apply: Most children will own six to eight colds a year in their first three years of life, and most are viral. It’s extremely simple to test for strep and for that you should own a [positive] culture [before treating with antibiotics].

Are the strategies for avoiding freezing and flu different?

Avoidance is extremely similar: Strict hand washing, not sharing drinking cups or utensils, and avoiding direct contact with people who are sneezing.

As endless as someone has a fever, they own the possibility to transmit infection. After they’ve had no fever for 24 hours, they’re not infectious.

The U.S. Centers for Disease Control and Prevention (CDC) now recommends that just about everyone get the flu shot: kids 6 months to 19 years of age, pregnant women, people 50 and up, and people of any age with compromised immune systems. Is the shot beneficial to anyone who gets it?

Unless you own a contraindication, there’s no reason not to get it. Contraindications would include egg allergy (because the vaccine is grown from egg products), any vaccines within a final week or two, and athletic illness at the time of your vaccine.