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Common Influenza Symptoms

By Emily Lockhart

Medically Reviewed by Dr. Gerald Morris

Initially, the influenza, or the flu, may be shrugged off as just a common cold due to similar symptoms, such as a runny nose, sinus congestion, sneezing, sore muscles, and sore throat.

However, a prime differentiator between cold versus flu is that similar symptoms will come on and worsen gradually with a cold as compared to the flu, which hits suddenly and hard with the following symptoms…

1. Fever

The initial sign that you have the flu and not just a routine cold, will be a high fever that soars between 102 and 106-degrees Fahrenheit (or 38-degrees Celsius). Typically, children’s fevers will be higher than adult fevers and can last 3 to 4-days before breaking.

2. Breathing Difficulty

Congestion and stubborn coughing will often cause constricted nasal passages and chest tightness/discomfort. As a result breathing can become restricted and labored. The flu can also make existing asthma or other breathing issues worse.

3. Chills

Periodic cold chills and sweating (particularly night sweats) as your fever comes and goes is very common with a nasty flu as your body fights the illness and pushes it out of your body.

4. Headache

Headache, or more commonly, nasal and sinus pain, due to congestion is very typical with the flu, which will worsen before it gets better.

5. Achy Muscles

Widespread aching muscles is very typical as the flu comes on. You’ll especially notice muscle tenderness in the back, arms, legs, and chest (if you have a stubborn cough).

6. Cough

Chest congestion that starts with a loose, hacking cough and develops into a persistent, dry cough is common with the flu. The persistent hacking can become severe and cause soreness in the throat and chest.

7. Nasal Congestion

Sinus and nasal congestion is common with the flu and common cold. However, with the flu, the chances of it developing into bronchitis, pneumonia, or a sinus infection are much higher, and for young children and seniors, it can be life-threatening.

8. Fatigue

Weakness that drains and completely exhausts you is common with the flu. Compared to a regular cold, the fatigue associated with the flu comes on rapidly and can last up to 2 or 3-weeks before your energy fully returns.

9. Sore Throat

One of the most common symptoms of the flu is a sore throat, which can be described as burning or scratchy. It may cause glands in the neck to swell and swallowing to become difficult.

10. Pain and Sensitivity of the Eyes

It is common for people with the flu to have aches and pains in their muscles, but they may also experience such feelings in and around their eyes, particularly when moving them. In addition, Livestrong says other ocular symptoms of the flu can include “sensitivity to light,” known as photophobia, and a “burning sensation.”

While the source says that these symptoms tend to go away on their own, in cases where the eyes are “very red, produce discharge or get worse instead of better,” it is advised that the individual seek medical attention.

11. Warm, Flushed, and Sweaty Skin

As mentioned earlier, a common symptom of the flu is a high fever, which can cause the skin to be warm, flushed, and sweaty, especially on the face. This happens because, when your internal temperature reaches fever level (99.5-degrees Fahrenheit or 37.5-degrees Celsius), the blood vessels close to the skin expand in order to help the body cool down.

The Merck Manual indicates that you may also notice this redness in other areas, such as the mouth, throat, or even in the whites of the eyes, which can appear bloodshot and watery.

12. Gastrointestinal Problems

While gastrointestinal problems are typically more indicative of gastroenteritis (often referred to as the “stomach flu”), it is possible for them to occur with influenza as well. Healthline says, “Some strains of the virus can cause diarrhea, nausea, stomach pain, or vomiting.”

Although these symptoms more commonly occur in children, it is possible for adults with influenza to experience them as well. With vomiting, in particular, if it becomes acute, WebMD stresses that you should seek immediate medical assistance, as it may mean your illness is severe.

13. Loss of Appetite

Loss of appetite is another common symptom of the flu, especially in those adults and children who experience gastrointestinal issues, such as nausea, vomiting, and diarrhea. With vomiting and diarrhea, in particular, the frequent loss of fluids can lead to dehydration, which is a major health concern. Livestrong encourages increasing your liquid intake by “sipping on hot tea, soups, and water.”

You can also help calm unsettled digestion by “eating a basic diet that consists of bland foods, such as toast, white rice, bananas, chicken, and boiled potatoes,” adds the source. But if keeping any food down is a challenge, it is advised that you make an appointment with your doctor.

14. Dizziness

In some cases, the flu may be accompanied by dizziness, which Livestrong indicates is “most often related to dehydration.” The source goes on to explain, “Dizziness occurs with dehydration due to reduced water in the circulation, which can cause a drop in blood pressure, especially when rising to a sitting or standing position.”

But dizziness isn’t always because of dehydration. Sometimes it occurs as a side effect of over-the-counter medications that people take to relieve their flu symptoms, particularly those that have antihistamines in them. The source adds that flu complications, such as pneumonia and inner ear infections, may also lead to dizziness.

15. Confusion

As mentioned earlier, dehydration is a major concern associated with influenza. This is because it can lead to a variety of other symptoms, including the dizziness just mentioned as well as confusion. When experiencing confusion, it’s possible that you may not know the day of the week or time of day or be able to understand what others are saying.

Additionally, confusion “impedes the ability to listen to one’s body and respond accordingly,” says As a result, it is considered by the Center for Disease Control and Prevention (along with dizziness) to be an emergency warning sign. Therefore, you should seek medical attention immediately if experiencing it.

MD, Family Medicine, Internal Medicine

Gerald Morris, MD is a family medicine/internal medicine physician with over 20 years expertise in the medical arena. Dr. Morris has spent time as a clinician, clinical research coordinator/manager, medical writer, and instructor. He is a proponent of patient education as a tool in the diagnosis and treatment of acute and chronic medical conditions.

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