A stomach virus, often colloquially referred to as the "stomach flu" or "stomach bug," is a microscopic organism that infects your digestive system. Unlike the common flu, which is caused by a respiratory virus, stomach viruses target the gastrointestinal tract. These viruses can cause inflammation and irritation of the stomach and intestines, leading to a range of unpleasant symptoms.

It's important to note that stomach viruses are not caused by bacteria. While bacteria can also cause food poisoning or other gastrointestinal illnesses, viruses are a different type of infectious agent. This distinction is crucial because antibiotics, which are effective against bacterial infections, are ineffective against viruses.

What are Some Common Stomach Viruses?

Norovirus, a highly contagious virus, is notorious for causing outbreaks in communal settings like schools, hospitals, and cruise ships. It can lead to severe vomiting and diarrhea, often resulting in rapid dehydration. Rotavirus, primarily affecting young children, is a major cause of severe diarrhea globally. However, widespread vaccination has significantly reduced its impact in many developed countries. Adenovirus is a versatile virus capable of causing various illnesses, including respiratory infections, eye infections, and gastrointestinal issues. While it can lead to stomach illnesses, symptoms are often milder compared to those caused by norovirus or rotavirus. Astrovirus is another common culprit of childhood diarrhea, causing vomiting, diarrhea, and fever.

What are The Symptoms?

The symptoms of a stomach virus typically manifest within 12 to 48 hours post-exposure. Common symptoms include nausea, vomiting, diarrhea, abdominal cramps, headache, fever, and fatigue. In severe cases, dehydration can occur, leading to dizziness, lightheadedness, and reduced urine output. While most individuals recover without complications, it's crucial to seek medical attention if you experience severe dehydration, persistent vomiting or diarrhea, blood in your stool, high fever, or severe abdominal pain. Dehydration, especially in vulnerable groups like young children and the elderly, can be dangerous and may necessitate intravenous fluid therapy. If you're concerned about your symptoms or experience severe dehydration, consult a healthcare provider.

Ways to Prevent It

While there's no foolproof way to avoid stomach viruses entirely, adopting these preventive measures can significantly reduce your risk of infection.

Frequent Handwashing

This is the single most effective way to prevent the spread of stomach viruses. Wash your hands thoroughly with soap and water, especially after using the bathroom, changing diapers, and before eating.

Sanitize Surfaces

Regularly clean and disinfect frequently touched surfaces, such as doorknobs, countertops, and toys, to eliminate viruses.

Avoid Contaminated Food and Water

Cook food thoroughly, avoid raw or undercooked foods, and drink clean water. Be cautious when traveling to areas with poor sanitation and consider boiling water before drinking it.

Practice Good Hygiene

Avoid touching your face with unwashed hands and cover your mouth and nose when coughing or sneezing. This helps prevent the spread of respiratory droplets that may contain viruses.

Although many people are only now becoming aware of it, adenovirus is being widely described as a “mystery illness spreading worldwide,” and that description feels accurate when you consider how many people are reporting symptoms at the moment. Adenovirus can cause fever, a runny nose, sore throat, and stomach discomfort, which makes it difficult to distinguish from a regular cold or the so-called “super flu” that is currently circulating. If you are feeling unwell, or concerned about catching an infection just before the holiday season, Dr Deborah Lee from Dr Fox Online Pharmacy explains how to tell adenovirus apart from the common cold and from the H3N2 flu strain.

What Is Adenovirus?

Adenovirus refers to a large group of viruses that can lead to infections ranging from mild to more severe. These viruses can affect the respiratory tract, eyes, digestive system, and urinary tract, often causing symptoms that look very similar to a cold or flu.

Adenoviruses are hardy, spread mainly through respiratory droplets, and can infect people throughout the year. Children and individuals with weaker immune systems may experience more serious illness, but most people recover with rest and fluids, according to the Cleveland Clinic.

Adenovirus vs Cold: How Does Adenovirus Differ From Common Cold?

Adenovirus is one of several viruses that can trigger cold-like symptoms. It helps to think of a cold as a set of symptoms rather than a single illness, with adenovirus being just one possible cause. “Adenovirus is just one virus that can cause the common cold,” says Dr Lee. She adds that many other viruses can also be responsible, including respiratory syncytial virus (RSV), rhinoviruses, parainfluenza viruses, and coronaviruses.

Identifying the exact virus behind your cold symptoms is very difficult. “It is pretty much impossible for you or a doctor to know which virus is causing your cold symptoms,” Dr Lee explains.

Adenovirus vs Flu: How Does Adenovirus Differ From The Flu?

“The flu can be extremely unpleasant, whereas adenovirus is usually mild,” Dr Lee says when comparing the two. She explains that flu symptoms often appear suddenly, sometimes within hours, and are usually marked by a high fever and severe discomfort.

According to Dr Lee, flu symptoms can include:

• A high temperature between 38°C and 40°C
• Joint pain and muscle aches
• Headache
• Sore throat
• Blocked or stuffy nose
• Dry cough
• Extreme fatigue

In contrast, adenovirus symptoms, when they appear at all, tend to develop slowly over several days, Dr Lee notes.

Other important differences between adenovirus and flu include:

• Adenovirus infections can occur at any time of year, while flu is more common during winter
• Adenovirus frequently causes pink eye, whereas influenza may lead to red or irritated eyes but less commonly
• Adenovirus often causes digestive symptoms such as vomiting and diarrhoea, while flu can cause these but does so less often
• Adenovirus is generally less likely to cause serious complications than influenza

Adenovirus: How To Tell If You Have Adenovirus Or Cold Or Flu?

Although adenovirus and common cold symptoms often overlap, the intensity of “super flu” symptoms usually stands out. Even so, Dr Lee explains, “The only way to really know the cause of your symptoms is to have a swab taken by a medical practitioner. This may be from the nose, throat, eye, urine, or stool.”

In most cases, testing is unnecessary and unlikely to be offered. “Because the vast majority of these viral infections are mild and self-limiting, this is rarely done,” says Dr Lee. “Treatment for any cold is symptomatic only.” She adds that extra caution is needed for babies and young children, older adults, pregnant women, and people with weakened immune systems.

A newly identified flu strain that spreads easily and causes more severe illness is driving infections this season. The strain, a mutated form of influenza A H3N2 known as subclade K, has been linked to a growing number of cases worldwide, including across the United States.

According to the World Health Organization, the K variant represents “a notable evolution in influenza A (H3N2) viruses,” prompting concerns among experts about how well this season’s flu vaccine may work against it.

Health specialists say the K variant is associated with stronger flu symptoms such as fever, chills, headaches, exhaustion, cough, sore throat, and a runny nose. A CDC report found that of the 216 influenza A(H3N2) samples collected since September 28, nearly 90 percent were identified as subclade K. As this strain continues to circulate, here is a closer look at the symptoms being reported and the areas where flu activity is currently highest.

New Flu Symptoms

Doctors say the symptoms caused by the mutated H3N2 strain closely resemble those of typical seasonal influenza A. Common symptoms include:

• Fever
• Chills
• Body aches
• Headache
• Severe fatigue
• Nasal congestion or a runny nose
• Cough

Flu symptoms often come on abruptly, Hopkins explains, describing it as a sudden, overwhelming feeling of being unwell.

The CDC notes that flu symptoms can overlap with those of COVID-19 and other respiratory viruses, making testing important. Three-in-one rapid home tests that check for influenza A, influenza B, and COVID-19 are now available, and experts advise keeping them on hand when possible. If you test positive for the flu, antiviral medications may help shorten the illness and lessen symptom severity, Hopkins adds.

Flu Shots: Where Is Subclade K Spreading In The US?

Below are the states and regions reporting the highest levels of medical visits related to flu-like illness, which may not reflect confirmed flu cases. The data reflects CDC reporting for the week ending December 25.

Very High (Level 1)

• New York City

Very High (Level 2)

• New York State

Very High (Level 3)

• New Jersey
• Rhode Island
• Louisiana
• Colorado

High (Level 1)

• Massachusetts
• Connecticut
• Michigan
• Idaho
• South Carolina

High (Level 2)

• New Mexico

High (Level 3)

• Washington, D.C.
• Maryland
• North Carolina
• Georgia

The CDC estimates that the flu has already caused at least 4.6 million illnesses, 49,000 hospitalizations, and 1,900 deaths so far this season. Health officials continue to recommend the flu vaccine as the most effective way to reduce the risk of serious illness.

Super Flu Symptoms: How to Protect Yourself From the Flu

During peak respiratory virus season, experts advise taking basic precautions to lower your risk and protect others:

• Keep vaccinations up to date.
• Get tested if symptoms appear.
• If you test positive, stay home until you are fever-free for 24 hours without medication and your symptoms are improving. If you do not have a fever, remain home for five days after symptoms begin.
• Avoid close contact with people who are sick.
• Wear a mask in crowded indoor settings.
• Wash your hands often.
• Cover your mouth and nose when coughing or sneezing.

Tramadol: A broad review of previously published studies suggests that tramadol, a powerful opioid often prescribed for long-term pain, provides only modest pain relief for the conditions it is most commonly used to treat. The conclusions come from a combined analysis of existing research, published online in BMJ Evidence-Based Medicine.

The review also highlights a greater risk of serious side effects, including heart-related problems. In light of these findings, the researchers say tramadol’s potential harms are likely to outweigh its benefits and advise that its use should be scaled back.

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What Is Tramadol?

Tramadol is a dual-mechanism opioid prescribed for moderate to severe pain, both short-term and long-lasting. For this reason, it features in several medical guidelines as an option for pain control, the researchers note. Prescriptions for tramadol have increased sharply over the past few years, making it one of the most widely used opioids in the United States.

This rise may be linked to the belief that tramadol causes fewer side effects and carries a lower risk of dependence than other fast-acting opioids. Although earlier systematic reviews have looked at tramadol, the researchers point out that no previous review has fully assessed both its effectiveness and safety across a wide range of chronic pain conditions.

Tramadol: Why Are Scientists Cautioning Against Tramadol Use?

According to Scitech Daily, the research team searched medical databases for randomized clinical trials published up to February 2025. These studies compared tramadol with a placebo, or dummy treatment, in people living with chronic pain, including cancer-related pain.

Nineteen clinical trials involving 6,506 participants with chronic pain met the criteria for inclusion. Five studies examined tramadol’s effect on nerve pain; nine focused on osteoarthritis; four assessed chronic lower back pain; and one looked at fibromyalgia. Eight trials also reported the rate of serious side effects during follow-up periods ranging from seven to sixteen weeks.

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Statistical analysis showed that tramadol was linked to about twice the risk of harm compared with placebo. This increase was largely driven by a higher number of cardiac events, including chest pain, coronary artery disease, and congestive heart failure. Tramadol use was also associated with a greater risk of certain cancers, although the researchers describe this finding as “questionable” due to the short follow-up period.

When all trial data were pooled, tramadol treatment was also tied to a higher likelihood of less severe side effects such as nausea, dizziness, constipation, and drowsiness. The researchers acknowledge that the study outcomes carried a high risk of bias. However, they add that this likely means the benefits of tramadol may be overstated while its risks could be underestimated.

Tramadol Side Effects

According to the NHS, like most medicines, tramadol can cause side effects, although not everyone experiences them. You should speak to your doctor or pharmacist if any of the side effects listed below trouble you or persist.

• Very common side effects
• Very common side effects affect more than 1 in 10 people and include:
• feeling sick
• feeling dizzy

Tramadol: Common Side Effects

These occur in more than 1 in 100 people. There are steps that can help manage them.

• headaches
• feeling sleepy, tired, dizzy, or “spaced out”
• nausea or vomiting
• constipation
• dry mouth
• sweating
• low energy

Tramadol: Serious Side Effects

Serious side effects affect fewer than 1 in 100 people.

Call your doctor or contact 111 immediately if you:

• feel dizzy, tired, and unusually low on energy, which may signal low blood pressure
• experience hallucinations, such as seeing or hearing things that are not there
• feel confused
• feel extremely sleepy
• have difficulty passing urine or are unable to urinate

Does Tramadol Lower Blood Pressure?

Yes, tramadol can cause a drop in blood pressure, known as hypotension, particularly when standing up suddenly. This can lead to dizziness or fainting, although it is not very common. In rare cases, tramadol may also raise blood pressure, and stopping the drug suddenly can trigger a spike in blood pressure. For these reasons, anyone with concerns about blood pressure should discuss them with their doctor, according to the NHS.