Ampligen for Chronic Fatigue Syndrome

Ampligen (rintatolimod) is an experimental anti-viral, immune-system modulating drug that's been in the works for more than 30 years. It's been studied as a possible treatment for multiple conditions, including chronic fatigue syndrome (CFS or ME/CFS), HIV/AIDS, certain types of cancer, both avian flu and swine flu (H1N1), and the Ebola virus.

In 2009 and again in 2013, the FDA rejected Ampligen as a ME/CFS treatment. It would have been the first approved treatment for this condition as well as providing Ampligen's entrance into the marketplace. In spite of these failures, the manufacturer continues to move ahead to get this drug approved.

Nurse adjusting IV bag for a patient
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How It Works

Ampligen is believed to work by jump-starting your body's natural anti-viral pathway and regulating levels of RNase L (a substance in your cells that attacks viruses), which can be high in people with ME/CFS. It's also been shown to inhibit tumor cell growth.

Ampligen doesn't appear to suppress the immune system. Instead, it's believed to change the way your immune system works.

Ampligen for CFS

In clinical trials, Ampligen has been shown to improve cognition, exercise tolerance, neuropsychological health and overall function in people with ME/CFS; decrease the activity of HHV-6 (a virus believed to be linked to ME/CFS), and decrease RNase L activity.

According to Ampligen's manufacturer, Hemispherx Biopharma Inc., more than 40,000 doses of Ampligen were given to about 500 patients in clinical trials at more than 20 U.S. clinics. One of those clinics, the Hunter-Hopkins Center, says 80% of its patients improved on Ampligen, and 50% improved significantly.

Because Ampligen isn't currently approved for any use in the U.S., only clinics with special permission can prescribe Ampligen. It's also incredibly expensive—as in more than $40,000 a year! And no, your insurance won't cover it, because it's experimental.

Ampligen also remains unapproved in the European Union, but some patients there may be able to get it through what's called an "early access program."


Ampligen is administered intravenously (I.V.). In trials and under conditional permits by the FDA, patients typically have received 400mg of the drug twice a week. Hunter-Hopkins recommends at least 12 months of therapy and 18 months for the severely ill.

Side Effects

Like any drug, Ampligen can cause unwanted side effects. Possible side effects include:

  • Mild flushing
  • Tightness of the chest
  • Rapid heartbeat
  • Anxiety
  • Shortness of breath
  • Feeling hot
  • Sweating
  • Nausea
  • Liver enzyme level changes
  • Diarrhea
  • Itching
  • Low blood pressure
  • Rash
  • Arrhythmias
  • Low white blood cell count
  • Dizziness
  • Confusion

Some patients have flu-like symptoms for a few hours after receiving a dose of the drug. The manufacturer says these effects typically went away after several months of treatment.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Strayer DR, Carter WA, Stouch BC, et al. A double-blind, placebo-controlled, randomized, clinical trial of the TLR-3 agonist rintatolimod in severe cases of chronic fatigue syndromePLoS One. 2012;7(3):e31334. doi:10.1371/journal.pone.0031334

  2. Mitchell WM. Efficacy of rintatolimod in the treatment of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME)Expert Rev Clin Pharmacol. 2016;9(6):755–770. doi:10.1586/17512433.2016.1172960

  3. Hunter-Hopkins Center, P.A. Ampligen is a step toward effective treatment.

  4. Klimov VV. From basic to clinical immunology. Springer. 2019.

Additional Reading

By Adrienne Dellwo
Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic.