An allergy, the common cold, the flu, and other infections can cause a sore throat. In addition to pain, there may be irritation, scratchiness, and swelling.
Identifying the cause of a sore throat is the first step toward treating it effectively.
If an allergy, a cold, or the flu is responsible, a sore throat generally responds well to home care. However, issues such as mononucleosis, tonsillitis, and a more severe flu can cause soreness that requires professional treatment.
A sore throat can be a symptom of coronavirus disease 2019 (COVID-19), but this is uncommon. The main symptoms of COVID-19 are a fever, a cough, and shortness of breath.
In this article, learn to differentiate between a sore throat caused by an allergy and one caused by a viral upper respiratory infection, such as the common cold or the flu.
We also describe treatment and prevention strategies and when to see a doctor.
Bacterial infections, allergic reactions, and viral infections — including a cold or the flu — can each cause a sore throat. Some people experience this regularly as a result of seasonal allergies.
To get a better idea of the underlying cause, take note of any other symptoms that appear.
Symptoms common to both colds and allergies include:
- a runny or stuffy nose
- coughing and sneezing
Symptoms of a cold, the flu, and other infections — but not usually allergies — include:
- a fever
- muscle and body aches
- swollen lymph nodes in the neck
If a person has itchy, watery eyes and a sore throat, the cause is most likely an allergic reaction, because these eye symptoms do not tend to occur with a cold or the flu.
Another important clue is how long a sore throat lasts. A cold or the flu tend not to last longer than 2 weeks.
However, an allergic reaction can last as long as the person is exposed to the allergen. For example, someone with a pollen allergy may have symptoms of a reaction for around 6 weeks, depending on the season.
Some people with seasonal allergies develop oral allergy syndrome after eating certain foods. Raw fruits, vegetables, and some tree nuts contain proteins that are similar to pollen, and these trigger symptoms of the allergy.
Oral allergy syndrome can cause:
- an itchy mouth
- a scratchy, irritated throat
- redness and swelling of the lips and mouth
- other seasonal allergy symptoms
Anyone who experiences a sore throat or other allergy symptoms after eating raw fruits or vegetables should speak to a healthcare provider, such as an allergist.
Allergies are very common — more than 50 million people in the United States alone have at least one allergy.
According to research from 2015, 15% of people in the U.S. have received a diagnosis of seasonal allergies, also called allergic rhinitis, and up to 30% of the population have self-reported nasal allergy symptoms.
Treatment of allergies depends on the severity of the symptoms.
The first step involves avoiding exposure to the allergen — entirely, if possible. There are usually several ways to minimize exposure to allergens, which we describe in the next section. A healthcare provider can give specific recommendations.
Next, if allergy symptoms are milder, a person may find relief from over-the-counter antihistamines, decongestants, and nasal steroid sprays.
A person with more severe allergy symptoms may need to take prescription medications — including methods of immunotherapy, such as allergy shots.
If a person pursues immunotherapy, it may involve attending a series of sessions with an allergist, who gradually exposes the person to increasing amounts of an allergen. Over time, this desensitizes the person, reducing their allergic response.
Many people use alternative therapies to treat allergies. According to the National Center for Complementary and Integrative Health, the following may help relieve symptoms:
Avoiding allergens is the best way to prevent the upper respiratory allergy symptoms, including a sore throat. However, completely avoiding an allergen is not always possible or practical.
Common allergens include:
- grass or tree pollen
- pet and animal dander
- mold spores
- dust mites
Some general tips to reduce allergen exposure include:
- keeping the windows closed during pollen season
- staying indoors, as much as possible, when the pollen count is high
- wearing sunglasses outdoors to protect the eyes from pollen
- showering and changing clothes after spending time outdoors during pollen season
- avoiding foods that trigger symptoms
- using dust-proof covers on furniture and bedding to reduce exposure to dust mites
- using a dehumidifier and cleaning the bathroom and kitchen frequently to reduce mold exposure
- washing the hands immediately after petting dogs and cats to reduce exposure to pet dander
- washing pets frequently to reduce dander buildup
When the cause of a sore throat is unlikely to be an allergy, a person can still take steps to relieve the issue, and any other symptoms, at home.
To ease a sore throat, a person should:
- Get some rest: The body needs it to fight the infection.
- Drink more fluids: These should be any temperature that feels best — the main goal is hydration, which helps combat the infection.
- Suck on throat lozenges: These help minimize pain and keep the mouth from becoming dry.
- Try Chloraseptic: This common, over-the-counter brand of oral analgesics helps numb the back of the throat, easing pain.
- Take ibuprofen or acetaminophen: These and other over-the-counter pain relief medications may help, but only if used as directed.
Whether a mild infection or an allergic reaction is causing a sore throat, a person can often ease the symptom at home.
Some home care strategies for a sore throat, regardless of the cause, include:
- sucking on ice chips or frozen fruit juices
- drinking hot tea with honey
- gargling with salt water several times a day
- using over-the-counter pain relief medication
However, if home remedies are not effective, consult a doctor or another healthcare provider.
A person should seek medical attention if a sore throat lasts longer than a week or two, and they experience any of the following:
- difficulty breathing or swallowing
- a high fever
- a rash
- blood in the saliva
- swelling or lumps in the face or neck
If a doctor suspects that an allergy is responsible for the symptoms, they can identify the specific allergen with testing.
A sore throat may be a symptom of an allergic reaction, a cold, the flu, or other types of infection. Because these issues often lead to similar symptoms, identifying the cause can be difficult.
One telltale symptom of seasonal allergies is itchy, watery eyes. Also, symptoms of a cold or the flu rarely last longer than 2 weeks, but allergy symptoms can last for 6 weeks or more.
A range of home care techniques can help treat a sore throat and other symptoms of infections and allergic reactions.
However, if symptoms are severe, or if self-care strategies and over-the-counter medications are ineffective, contact a doctor.