Since there are tens of thousands of treatments a day in the world of medical ozone, there is plenty of evidence of efficacy and side effects.
Numerous clinical investigations have confirmed that ozone therapy, if properly indicated, dosed, performed etc., is well-tolerated by patients and very seldom can cause any side effects.
During and after the procedure, patients may complain about weakness, slight dizziness, or sleepiness that last for a short time. Allergic skin reactions (like nettle rash) are possible with local applications of ozone although they occur very seldom.
According to available statistical data, in the past (Oepen, 1985) the frequency of side effects was 1:1000 – 1:2000. The study looked at 384,775 patients and documented only a 0.000005% rate of adverse side effects. This is much safer than any drug including aspirin.
In Germany it is reported that ozone side effects are typically minor irritations that are caused by incorrect application and quickly disappear.
What can you expect?
There are almost no side effects from the appropriate use of medical ozone. If used improperly there can be some problems, but even those are minor. As many people have infections and ozone works to kill infectious germs, there is always the possible reaction of toxic die-off (herx response). This can be true of antibiotics too.
The U.S. Food and Drug Administration (FDA) reports that 1.5 million people were hospitalized in the United States due to side effects from medication. In the US, annual prescription drug deaths are equal to a jumbo jet liner crashing and killing all aboard 365 days of the year