IGF-1 Side Effects

IGF-1 seems to be just as controversial as it is popular. A recent New York Times article investigating IGF-1 begins by enumerating the many positive aspects of IGF-1:

“In theory, at least, IGF-1 seems almost too good to be true. It can, at least in animals, heal tendon injuries and build muscles…it is believed to make an athlete bigger, faster and stronger. It may boost muscle, reduce fat and improve endurance.”[1]

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Athletes, of course, are forbidden by organizations like the World Anti-Doping Agency to take performance enhancing drugs such as IGF-1. But what are the consequences for someone wanting to take IGF-1 recreationally?

This is where the controversy comes in. Despite IGF’s benefits, there are several side effects to consider.

IGF-1 Short Term Side Effects

One of the most common short-term side effects reported from IGF-1 usage is hypoglycemia, a disorder characterized by an abnormally low level of blood sugar.[2][3]

Many believe this is because IGF-1 binds to two cell surface receptors: IGF-1 receptor and the insulin receptor. When it binds to the insulin receptor, it activates the receptor at a smaller potency than insulin.[4] Though, this effect is primarily observed in animals, not human subjects.

Still, hypoglycemia risk is a contributing factor to the reason IGF-1 is limited in clinical application.[5]

IGF-1 Long-Term Side Effects

A review of published literature on IGF-1 and growth hormone published in the British Journal of Pharmacology maintains much more is known about short-term IGF-1 side effects, as experience with exogenous IGF-1 use is limited.[6]

These researchers, however, hypothesize the long-term side effects from IGF-1 are similar to those of growth hormone: “many of the longer-term effects of GH administration would also occur with IGF-I, as the anabolic effects of GH are closely related to the production of IGF-I in different tissues.”[7]

Further insight into long-term IGF-1 side effects is provided in an article examining long-term study and treatment of children and adults with Laron Syndrome. “Overdosage led to adverse effects such as hypoglycemia, edema, swelling of soft tissues, and hyperandrogenism.”[7]

IGF-1 Side Effects in Athletes

IGF-1 has a growth stimulating effect, independent of and in conjunction with human growth hormone.[8] According to researchers, IGF-1 achieves this effect by suppressing protein breakdown and preserving skeletal muscle.[9]

Too much IGF-1, however, in the blood causes bone growth that causes changes in physical appearance.[10] Researchers have observed: “it would be reasonable to expect that athletes may develop some of the features of acromegaly (abnormal hands, feet, and face growth) with prolonged use.”[6]

Additionally, one of the more hazardous IGF-1 side effects observed in athletes is cardiomyopathy, a disease which enlarges and weakens the heart.[11] Too much GH and IGF-I results in cardiomyocyte derangement and leads to heart abnormalities, as well as problems with cardiac rhythm and heart valves.[6]

IGF-1 and Cancer

An article published in Endocrine Care examined the relationship between cancer mortality and IGF-1. A population based study was conducted involving 633 men aged 50 years and older, who had IGF-1 measured in their blood after attending a clinic between 1988-1991.

The participants were tracked through July 2006, with the study concluding, “Higher serum IGF-I in older men is associated with increased risk of cancer death, independent of age, adiposity, lifestyle, and cancer history.”[12]

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