Influenza, commonly called the flu, is a respiratory infection caused by the influenza virus. It is contagious, which means it passes easily from one person to another. Although influenza viruses can circulate throughout the year, infections are seen more often during the fall and winter months. This time is known as the flu season. As flu cases are rising across many parts of the US and UK, here are a few key points to understand, from the incubation period to how easily the virus spreads.

What Is The Flu (influenza)?

The flu is an infection caused by the influenza virus. It usually leads to symptoms such as body and head aches, sore throat, fever, and breathing-related discomfort, which can sometimes become serious. Flu cases tend to peak during the winter months, when large numbers of people may fall ill at the same time, a situation described as an epidemic, according to the Cleveland Clinic.

Flu: What Is The Incubation Period Of The Flu?

The average incubation period of the flu is around 2 days, though it can vary from 1 to 4 days. In simple terms, this means most people begin to notice flu symptoms a few days after the virus enters the body.

When Does The Flu Become Contagious?

After catching the flu virus, a person can start passing it on to others about 1 dayTrusted Source before symptoms appear. Keep in mind that the usual incubation period is about 2 days. So, if someone is exposed to the virus on a Saturday morning, they may already be able to spread it by Sunday evening. By Monday afternoon, flu symptoms are likely to show up. These symptoms can be mild or severe.

Some people may not develop symptoms at all, but they can still spread the virus. The flu is usually most contagious during the first 3 days of illness. After symptoms begin, a person may continue to infect others for another 5 to 7 days. Children, older adults, and people with weaker immune systems may remain contagious for a longer time.

Flu Symptoms 2025: Early Symptoms You Need To Take Care Of

Unlike the common cold, which tends to develop slowly, flu symptoms often appear suddenly.

Common symptoms include:

• feeling extremely tired, exhausted, or weak
• headache
• blocked or runny nose
• sore throat
• dry cough
• muscle and body aches
• fever or chills, although not everyone gets these
• vomiting or diarrhoea, which is seen more often in children

Most people start to feel better within a few days to two weeks. However, some individuals may need antiviral medication, particularly those at higher risk of serious complications.

How Does The Flu Spread?

The flu mainly spreads through tiny respiratory droplets released when an infected person coughs or sneezes. In crowded places, these particles can be inhaled by others, leading to infection. The virus can also spread by touching objects or surfaces that carry the virus, such as door handles or shared personal items. Outside the body, the virus can survive on surfaces for up to one day.

If someone touches a contaminated surface and then touches their eyes, nose, or mouth, the flu virus can enter the body and cause infection.

A little-known virus is spreading steadily across different parts of the world, prompting growing concern among health experts. Often described as “untreatable” because there is no targeted antiviral medicine available, adenovirus is drawing attention due to how tough it is and how quickly it can pass from person to person.

Eric Sachinwalla, medical director of infection prevention and control at Jefferson Health, has cautioned that while most healthy individuals develop only mild illness, people in high-risk groups may face more serious health problems. This raises an important question: just how contagious is this mystery illness that is spreading?

Adenovirus: How Contagious Is It?

Yes, adenovirus is highly contagious and spreads with ease in several ways. It can pass through respiratory droplets released during coughing or sneezing, close physical contact such as hugging or shaking hands, and contact with contaminated surfaces like toys and towels.

It can also spread through fecal matter, particularly during diaper changes, and in some cases through water. According to the CDC, the virus spreads quickly in crowded settings such as schools and daycare centres and can survive for long periods on surfaces, making good hygiene especially important for young children and people with weakened immune systems.

Who Do Adenoviruses Affect Most?

Adenoviruses can infect people of all age groups, but they are most commonly seen in children under the age of five. In babies and young children, the virus often spreads in daycare environments where close contact is common. Children are also more likely to put shared objects in their mouths and may not wash their hands as regularly.

Among adults, adenoviruses tend to spread in crowded living conditions. People staying in dormitories or military housing may have a higher risk of infection. The virus is also known to circulate in hospitals and nursing homes, as per CDC.

Those with weakened immune systems are more likely to become seriously ill from an adenovirus infection. This includes people who have undergone organ or stem cell transplants, as well as those living with cancer or HIV/AIDS. Individuals with existing heart or lung conditions may also face a higher risk of severe illness.

Adenovirus: What Are The Symptoms Of An Adenovirus Infection?

The symptoms of an adenovirus infection depend on the part of the body affected. Most commonly, the virus targets the respiratory system. When it infects the airways, it can cause symptoms similar to a cold or the flu. These may include:

• Cough.
• Fever.
• Runny nose.
• Sore throat (pharyngitis).
• Pink eye (conjunctivitis).
• Ear infection (otitis media).
• Swollen lymph nodes.
• Chest cold (bronchitis).
• Pneumonia.

Adenoviruses can also infect the digestive system. When this happens, diarrhea may occur, along with gastroenteritis. Gastroenteritis is inflammation of the stomach or intestines and can lead to stomach pain, diarrhea, nausea, and vomiting.

In rarer cases, adenoviruses can affect the bladder or the nervous system. Infection of the bladder may result in urinary tract infections. When the nervous system is involved, it can lead to serious conditions affecting the brain, including encephalitis and meningitis.

People who are prescribed blood thinners, also known as anticoagulants, could unknowingly weaken the effect of their medication by eating a widely consumed and otherwise healthy vegetable, a doctor has warned.

What Are Anticoagulants?

Anticoagulants are routinely given to reduce the risk of blood clots and are often prescribed to those who face a higher chance of such complications. This group also includes people at increased risk of heart attacks or strokes. These medicines, which include rivaroxaban, apixaban and warfarin, work by interrupting the clotting process and play a key role in preventing serious conditions such as strokes, heart attacks, pulmonary embolism and deep vein thrombosis.

Warfarin: Why This Common Vegetable Can Be A Problem

While anticoagulants are effective and often lifesaving, patients are being advised that a familiar garden vegetable could interfere with how well these drugs work. The warning comes from Dr Chris Steele, who appeared on ITV’s This Morning to explain how certain foods can interact negatively with different medications.

As part of his advice, he said, as per Express, “Leafy greens are high in vitamin K, which helps blood to clot. Warfarin works by blocking vitamin K production, so if you suddenly increase how many greens you eat, it can affect how the medicine works.”

He added: “Other foods that contain a lot of vitamin K include green vegetables, egg yolks, chickpeas and lentils. These foods don’t need to be removed from the diet, but it is important to keep your intake steady and consistent. You should also avoid drinking large amounts of cranberry juice or using cranberry products while on anticoagulants, as they can alter the effect of warfarin. Garlic and ginger should be limited too, as they can raise the risk of bleeding.”

Warfarin: Other Food And Drug Interactions To Watch For

Dr Chris also highlighted that many other medicines can react in unexpected ways when taken alongside certain foods and drinks. For example, he noted that some antibiotics, including ciprofloxacin, can react poorly with milk.

He explained: “Calcium can reduce how well some antibiotics work, so these medicines should not be taken at the same time as foods high in calcium, such as milk, yoghurt or cheese. Calcium supplements should also be avoided for a few hours before and after taking these antibiotics.

“You should not drink milk when taking certain antibiotics, including tetracycline and ciprofloxacin, which are quinolone antibiotics, or some osteoporosis drugs like alendronate, also known as Fosamax.”

He further advised avoiding the following combinations with specific medicines:

• Grapefruit if you are taking statins for high blood pressure
• Black liquorice if you are on certain heart medicines such as digoxin
• Bananas if you take some ACE inhibitors for high blood pressure
• Coffee if you use bronchodilators for asthma
• Smoked salmon and salami if you are prescribed antidepressants
• Limes if you are taking cough medicine

Dr Chris stressed: “Always speak to your doctor about any precautions you should follow when starting a new medication. You may need to avoid certain foods, make changes to your lifestyle, or take other steps to prevent unwanted side effects.”

While flu was already going around the world, now, a new virus has surged, which, experts have called it 'untreatable' and alerted that even disinfectants are not enough to get rid of it. This is adenovirus is a newly emerging mystery virus that is being described as stronger than Covid and even flu, which is now spreading across the several parts of the world.

What Are The Unique Symptoms Of Adenovirus?

While a lot of the symptoms mimics of those in flu or COVID, including shortness of breath, a sore throat and or a runny nose. However, there are certain unique symptoms of adenovirus that include:

• Diarrhea
• Pink Eye or conjunctivitis
• Ear infection or otitis media
• Swollen lymph nodes
• Pneumonia
• Stomach pain
• Nausea
• Vomiting

Other rare symptoms could also include impact on your bladder or nervous system. As viruses in your bladder can also cause urinary tract infections, and the same virus in your nervous system can cause condition that can affect your brain. These conditions also include encephalitis and meningitis.

How Long Does The Infection Last?

Most adenovirus symptoms last from a few days to up to two weeks. Severe infections could take longer, including, as they can continue to linger for a while, such as a cough.

What makes this virus unique is that it can spread through easily. Adenovirus is highly contagious. It can spread from one person to another through shaking hands, kissing, or even hugging. The virus could also spread through sneezing, coughing, and if by any other means respiratory droplets transfers to other person in air. It can also spread by touching contaminated surface, and you can get the virus by touching your eyes, nose, or mouths if you do not wash your hands.

The virus can also spread through stool of an infected person. For instance, you can be infected while changing your baby's diaper. It can also spread through unchlorinated water, and a person can be infected with the virus if he or she swims in a pool without adequate chlorine.

Adenoviruses are resistant to many common disinfectants. Therefore, they can remain infectious on surfaces for a long time.

Read: This Mysterious New Virus Could Spread Faster Than Covid-19 And Flu

Adenovirus: How Is Adenovirus Different From Covid And Flu?

Adenoviruses, like coronaviruses, spread from person to person and can trigger similar respiratory symptoms. However, they belong to entirely different virus families and behave differently. One key difference is resistance. Coronaviruses are more easily destroyed by disinfectants, while adenoviruses are harder to kill, which allows them to spread more easily than Covid or flu.

For otherwise healthy individuals who feel unwell but do not have severe symptoms such as high fever or breathing difficulty, recovery usually happens at home with basic supportive care. Medical attention is more important for people with weakened immunity, parents of very young infants, or those with existing conditions like heart or lung disease. If symptoms appear, experts advise against walking straight into a clinic. Calling ahead is safer, as doctors may recommend a telehealth consultation if the illness seems highly contagious.