Influenza treatment

Treatments for influenza include a range of medications and therapies that are used in response to disease influenza. Treatments may either directly target the influenza virus itself; or instead they may just offer relief to symptoms of the disease, while the body's own immune system works to recover from infection.

The two main classes of antiviral drugs used against influenza are neuraminidase inhibitors, such as zanamivir and oseltamivir, or inhibitors of the viral M2 protein, such as amantadine and rimantadine. These drugs can reduce the severity of symptoms if taken soon after infection and can also be taken to decrease the risk of infection. However, virus strains have emerged that show drug resistance to both classes of drug.

Symptomatic treatment

• Stay at home

• Get plenty of rest

• Drink a lot of liquids

• Do not smoke or drink alcohol

• Consider over-the-counter medications to relieve flu symptoms

• Consult a physician early on for best possible treatment

• Remain alert for emergency warning signs

• Difficulty breathing or shortness of breath

• Pain or pressure in the chest or abdomen

• Dizziness

• Confusion

• Severe or persistent vomiting

Peramivir
Interferons

The United States authority on disease prevention, the Centers for Disease Control and Prevention (CDC), recommends that persons suffering from influenza infections:

Warning signs are symptoms that indicate that the disease is becoming serious and needs immediate medical attention. These include:

In children other warning signs include irritability, failing to wake up and interact, rapid breathing, and a blueish skin color. Another warning sign in children is if the flu symptoms appear to resolve, but then reappear with fever and a bad cough.

Peramivir, an experimental anti-influenza drug, developed by BioCryst Pharmaceuticals has not yet been approved for sale in the United States. This drug can be given as an injection, so may be particularly useful in serious cases of influenza where the patient is unconscious and oral or inhaled drug administration is therefore difficult.

In October 2009, it was reported that the experimental antiviral drug Peramivir had been effective in treating serious cases of swine flu. On October 23, the U.S. Food and Drug Administration (FDA) issued an Emergency Use Authorization for Peramivir (now expired), leading to wider and faster availability for patients. Since the FDA's decisions and actions are closely watched around the world, this move is likely to also increase demand for Peramivir internationally.

Interferons are cellular signalling factors produced in response to viral infection. Research into the use of interferons to combat influenza began in the 1960s in the Soviet Union, culminating in a trial of 14,000 subjects at the height of the Hong Kong Flu of 1969, in which those treated prophylactically with interferon were more than 50% less likely to suffer symptoms, though evidence of latent infection was present. In these early studies leukocytes were collected from donated blood and exposed to a high dose of Newcastle disease, causing them to release interferons. Although interferon therapies became widespread in the Soviet Union, the method was doubted in the United States after high doses of interferon proved ineffective in trials. Though the 1969 study used 256 units of interferon, subsequent studies used up to 8.4 million units. It has since been proposed that activity of interferon is highest at low concentrations. Phase III trials in Australia are planned for 2010, and initial trials are planned in the U.S. for late 2009.

Interferons have also been investigated as adjuvants to enhance to effectiveness of influenza vaccines. This work was based on experiments in mice that suggested that type I interferons could enhance the effectiveness of influenza vaccines in mice. However, a clinical trial in 2008 found that oral dosing of elderly patients with interferon-alpha actually reduced their immune response to an influenza vaccine.

Viferon is a suppository of (non-pegylated) interferon alpha-2b, ascorbic acid (vitamin C), and tocopherol (vitamin E) which was reported in two small studies to be as effective as arbidol. It is sold in Russia for $4–$9 per suppository depending on dose. Another interferon alfa-2b medicine, "Grippferon", nasal drops, is used for treatment and emergency prevention of Influenza and cold. Its manufacturers have appealed to the WHO to consider its use against avian influenza and H1N1 Influenza 09 (Human Swine Flu), stating that it was used successfully in Russia for eight years, but that "the medical profession in Europe and the USA is not informed about this medicine".