Cold and flu aren’t the same. Many people can get through a cold without serious problems, but unlike the common cold, influenza puts hundreds of thousands of people in the hospital every year. The bug responsible for the majority of flu cases is the influenza A virus, and it’s a potentially serious infection.
What is influenza A?
Influenza A is among the most common infectious diseases among humans and is responsible for periodic global flu pandemics, making the virus nothing less than a major global public health threat.
Influenza is a highly contagious viral infection of the nose, throat, and lungs and is easily spread from person to person through water droplets and aerosols. Transmission of influenza is primarily through coughs, sneezes, and talking, but the virus can easily be picked up from contaminated surfaces such as tables and money.
Influenza A represents one of four types of influenza virus—A, B, C, and D—but only types A, B, and C can infect people. However, type A influenza is the powerhouse version; 75% of human flu cases are influenza A infections and the remainder are caused by the influenza B virus. Influenza C virus infections are rare and comparatively mild infections.
Influenza A, however, is the influenza virus responsible for global influenza pandemics. Some of the deadliest strains of the flu virus, such as avian flu, are subtypes of influenza A. Unlike the influenza B virus, which only infects humans, influenza A infects both humans and animals. Sometimes, influenza A strains such as swine flu, cross over into humans where they can set off an epidemic. Other strains of influenza A rarely cross from animals to humans, but, when they do—in cases such as avian influenza (bird flu)—they can be deadly.
Influenza A subtypes are named for two principal proteins that stick out of their outer envelope, hemagglutinin and neuraminidase. These spike-like proteins help the virus attach to human cells as well as break into and out of cells. There are 18 different types of hemagglutinin and 11 different types of neuraminidase found on influenza A viruses, so each subtype is named from the number of each of these proteins. For instance, the H1N1 virus, or swine flu, is the most common subtype of influenza A virus to infect people.
Fortunately, most influenza A infections resolve without treatment in five to seven days. Some people, however, are prone to potentially life-threatening complications that may require hospitalization. The most common and most dangerous is pneumonia, either viral or bacterial. Other serious complications include ear infections, heart problems, bronchitis, myocarditis (swelling of the heart), or Reye’s syndrome. An influenza virus infection could also worsen existing conditions such as congestive heart failure.
Symptoms of influenza A infection commonly include:
Fever
Chills
Cough
Sore throat
Body aches
Headache
Fatigue
Nasal congestion
Swollen, itchy, or watery eyes
It is not uncommon to experience nausea, vomiting, or diarrhea with a flu infection.
Flu, however, can turn into a severe disease. Flu symptoms that require immediate medical care include:
High fever for several days
Difficulty breathing when at rest or during mild exertion
Blue skin (cyanosis)
Rapid breathing
Severe vomiting
Confusion or disorientation
Fast heartbeat
Low blood pressure
Chest pain
Another warning sign is when symptoms improve for a bit and then get worse. This could mean a secondary pneumonia infection has set in.
How is influenza A diagnosed?
Most flu cases are diagnosed from the symptoms, especially when seasonal influenza is going around. Patients at risk for complications, however, will have their blood tested for influenza A antibodies or genetic material to confirm the symptoms. These tests are rapidly completed, usually in about 30 minutes, so high-risk patients can begin treatment on antiviral medications. Other tests include rapid influenza diagnostic tests (RIDTs) and nasal/mouth swabs.
Risk factors for flu complications include:
Age (over 65 or under 2)
Asthma
Cancer,
Heart disease
Chronic lung, kidney, or liver disease
Pregnancy
Stroke
Obesity
Cystic fibrosis
Diabetes
Children and teens taking aspirin or similar drugs, children with neurological disorders, and patients in nursing homes also have a higher risk of complications.
For hospitalized high-risk patients, the final diagnosis will be determined by a polymerase chain reaction (PCR) test that will identify genetic material unique to the virus. Chest X-rays, CT scan, and other testing, may be required if the doctor is worried about complications.
Influenza A treatment options
The good news is that most influenza A infections run their course for a few days without requiring treatment other than a few days of rest and some supportive care. Influenza A, however, can be a serious respiratory illness, so some cases will require antiviral medications or hospitalization.
Vaccination
Seasonal flu vaccines produce immunity against two different strains of influenza A. There are, however, many other strains of influenza A out there, so influenza vaccine will not provide immunity against these different strains or different influenza types. Also, the influenza A virus constantly mutates, so influenza immunity is always a moving target even during a single influenza season. For this reason, historically vaccination prevents flu infections in only 19% to 60% of people receiving the flu shot according to the Centers for Disease Control and Prevention (CDC). On average, though, one out of two people given a flu shot will avoid seasonal flu. The CDC and almost all healthcare providers across the board recommend that everyone six months old and older get a flu vaccine.
Medications
To handle the aches, coughing, sniffles, and fever, over-the-counter medications that relieve those and other symptoms are enough to help people through an influenza A infection.
Hospitalization
Influenza A can become a serious health-threatening condition. Over the last 10 years, data from the CDC has shown that the hospitalization rate has varied from as low as 140,000 to as high as 810,000. Treatment will consist of monitoring, supportive care, oxygen, antiviral medications to fight the flu virus, antibiotics to prevent bacterial pneumonia, and, if necessary, mechanical ventilation.
Influenza A medications
Influenza A is primarily treated with bed rest, fluid intake, and symptom relief. Fortunately, a few days of bed rest will get most people past the worst part. The best treatment, however, is prevention, which is why healthcare providers nearly unanimously advise getting a flu vaccination at the start of flu season. Flu vaccines, however, are not 100% effective, so some people will still get the flu and require symptom relief medications or, in severe cases, antiviral drugs.
Vaccines
Flu vaccines are widely available and inexpensive. There are many influenza strains, so each year’s influenza vaccine targets the strains believed most likely to cause an epidemic in that year. Trivalent vaccines produce immunity against two influenza A strains and one influenza B strain. Quadrivalent vaccines provide immunity against two influenza A strains and two influenza B strains. Both trivalent and quadrivalent vaccines target the same two influenza A strains. H1N1 influenza, or swine flu, is usually one of the strains targeted in the annual vaccine. Immunity develops in about two weeks after a flu shot.
Symptom relief medications
Several over-the-counter medications can be used to relieve flu symptoms. None of these medications fight off the virus, but they make life more tolerable as the body’s immune system clears the infection. They will include ingredients such as:
Analgesics such as acetaminophen or non-steroidal anti-inflammatory drugs (NSAIDs) reduce muscle aches, headache, and fever
Antitussives (cough medicine) such as dextromethorphan relieve cough
Nasal decongestants such as pheniramine reduce swelling in the nasal passages
Expectorants such as guaifenesin loosen mucus in the air passages.
Most over-the-counter commercial “flu” medications combine two or more of these types of drugs.
Antiviral medications
Antiviral medications directly target the virus itself, interfering with its ability to infect cells in the body. These include Tamiflu (oseltamivir), Rapivab (peramivir), Relenza, (zanamivir), and Xofluza (baloxavir marboxil). They are highly effective at rolling back an influenza A infection if they are given within a day or two after symptoms first appear. At later stages, more than 36 hours after the first appearance of symptoms, these antiviral drugs are used to prevent complications or bring a severe infection under control. Both Tamiflu and Relenza can also prevent an influenza A infection and are prescribed to the highest-risk patients to take throughout the influenza season but are not a substitute for the flu vaccine.
What is the best medication for the flu?
If you ask most medical professionals what flu medication they would recommend, most would tell you to get a flu vaccination before the start of flu season. Otherwise, the “best” medication for most cases of flu is to rest and drink fluids. However, people at risk for complications may require antiviral medications early in the infection. Antivirals may not be appropriate for every patient.
Many of the standard dosages above are from the U.S. Food and Drug Administration (FDA) and the National Institutes of Health (NIH). Dosage is determined by your doctor based on your medical condition, response to treatment, age, and weight. Other possible side effects exist. This is not a complete list.
What are the common side effects of flu medicine?
Flu vaccines have a long track record showing them to be very safe. While most people experience side effects, these effects are limited to immediate reactions to the injection, such as minor pain, redness, rash, or a hard lump forming at the site of the injection. Some people experience a low-grade fever, mild muscle pain, or a mild headache that lasts for one or two days after receiving the injection.
Over-the-counter symptom relief products also have few and only minor side effects, mostly muscle aches, sleepiness, headache, drowsiness, and dizziness, but side effects will depend on the ingredients.
Antiviral drugs are prescription medications with potentially serious side effects, such as delusions and potentially fatal skin reactions, but these are rare. The most common side effects involve the digestive system: nausea, vomiting, and diarrhea. Flu-like symptoms such as sinus congestion, runny nose, fever, and bronchitis are also common.
What is the best home remedy for the flu?
Home remedies, unfortunately, will do little to alter the course of a flu infection. Home treatments can help relieve symptoms, but no home remedy cures the flu. It’s best to stick with the fundamentals: rest, fluids, and symptom relief.
Rest
Your body will take care of the infection. Give it the rest and resources it needs to fight the good fight.
Fluids
For as long as people have been getting the flu, taking in enough water and electrolytes have always been the most effective way to keep symptoms at bay and fight off the infection.
Symptom relief
Over-the-counter medications, dietary supplements, and natural herbs will make symptoms more bearable. For natural remedies, try zinc, vitamin C, black tea, or echinacea. A vaporizer or steamy shower can help relieve sore throat, cough, and nasal congestion.
Frequently asked questions about influenza A
What drug is indicated for influenza type A?
The drug of choice for influenza A is a seasonal flu vaccine to prevent infection in the first place. If the flu strikes despite vaccination, which does happen, most cases will resolve without medications or other treatment in five to seven days. For some patients patients, antiviral drugs such as Tamiflu (oseltamivir), Relenza, (zanamivir), Rapivab (peramivir), or Xofluza (baloxavir marboxil) will be given shortly after symptoms appear.
Do I need antibiotics for influenza A?
Antibiotics fight bacterial infections and are not effective against viral infections such as flu.
Does Tamiflu work for influenza A?
Tamiflu (oseltamivir) effectively treats influenza A if administered within one or two days after the first appearance of influenza A symptoms (fever, fatigue, sore throat, cough, muscle aches, headache). If taken later than that, Tamiflu can reduce the severity and contagiousness of the infection as well as reduce the risk for serious complications. Tamiflu is also highly effective at preventing influenza A infection after someone has been exposed to the influenza virus.
What helps get rid of influenza A?
Influenza A can be effectively treated with antiviral medications such as Tamiflu (oseltamivir), Relenza, (zanamivir), Rapivab (peramivir), or Xofluza (baloxavir marboxil) provided they are administered within one or two days after the first appearance of symptoms. Other medications, natural remedies, and home remedies can help relieve influenza A symptoms but will not get rid of the infection.
Can you recover from influenza A without medication?
In most cases, people recover from influenza A in a few days without treatment.
How long does influenza A usually last?
Influenza A symptoms begin one to four days after exposure and last for another five to seven days.
How serious is influenza A?
Influenza A is a potentially serious respiratory infection that in most people resolves in a few days without treatment. It is highly contagious and can cause serious complications such as pneumonia and other infections. In high-risk populations—the elderly, pregnant women, young children, or people with cancer, heart disease, diabetes, or compromised immune systems—complications can be serious enough to result in hospitalization or death.
Nicole Galan is a registered nurse who currently works as a freelance writer and subject matter expert for consumer health websites and review programs for nursing students. Nicole recently completed her Master’s Degree in Nursing Education and lives in Southern California with her husband and three sons.
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