Andarine is a SARM developed to treat muscle wasting and osteoporosis. It has shown promise in animal studies, where it effectively increased bone density, muscle mass, and strength. However, it was abandoned in early human clinical trials. It is still popular among athletes because of its muscle-building and fat-reducing effects. Read on to learn more about this drug and its side effects.
Note: By writing this post, we are not recommending this drug. Some of our readers who were already taking the drug requested that we commission a post on it, and we are simply providing information that is available in the scientific literature. Please discuss your medications with your doctor.
What Is Andarine?
Andarine, also known as S-4, S-40503, or 8, is a SARM developed with the aim of treating osteoporosis and muscle wasting.
SARMs (selective androgen receptor modulators) are drugs that bind to the androgen receptor (AR), which is the main site of action of the hormone testosterone.
In the early days, Andarine was described as the ideal SARM due to high oral bioavailability and great muscle- and bone-building effects (studied in animals) [R].
Phase I human trials with this drug have reportedly been successful but no studies have been published. However, further development of the drug was abandoned in favor of Ostarine, another SARM with a similar structure, also known as S-22 [R].
We can presume that this was either because Ostarine was more effective, or because Andarine caused vision-related side effects (see below).
Mechanism of Action
Andarine has a high affinity for the androgen receptor (AR) and therefore mimics the effects of testosterone. However, its effects are much stronger in muscles and bones than in reproductive organs. That is why Andarine and other SARMs cause fewer side effects than anabolic steroids [R].
Uses of Andarine
1) May Increase Muscle Mass
This drug was developed to prevent muscle wasting, and animal studies do indeed show that Andarine improves muscle growth and strength in animals.
When given to castrated rats for 4 weeks, Andarine increased muscle weight as markedly as DHT (dihydrotestosterone). Moreover, unlike DHT, Andarine caused no prostate enlargement, which is a concern when taking steroids [R].
Twelve weeks after castration, Andarine was able to restore lean body (muscle) mass in rats [R].
2) May Increase Bone Strength and Combat Osteoporosis
Andarine increased bone mineral density and strength in both in castrated male rats and in female rats whose ovaries had been removed (this is a commonly used animal model of osteoporosis) [R, R, R, R].
3) May Help Fat Loss
In female rats whose ovaries have been removed, apart from improving bone strength, Andarine also decreased body fat [R].
Risks and Side Effects
SARMs, in general, have fewer side effects than anabolic steroids, because of their selectivity. They have low activity in reproductive tissues. Andarine, therefore, shouldn’t cause male breast enlargement, elevated blood pressure, hair loss, acne, or the appearance of masculine traits in women (these can be observed in people who use anabolic steroids).
LH (luteinizing hormone) and FSH (follicle stimulating hormone) promote the production of reproductive hormones in men and women, and their suppression could suppress normal estrogen/testosterone levels. Andarine suppressed LH and FSH in castrated rats where these hormones were elevated as a result of castration. However, it had no effect in normal male rats [R, R].
It is unknown if and how much Andarine would suppress testosterone/estrogen production in humans.
The most frequent user-reported side effects are visual issues such as a yellow tint and difficulty adjusting to night vision. These disappear after the drug has been discontinued. Higher doses seem to cause stronger side effects.
Some users also report depression.
Legality, Sports, and Doping
Since 2008, use of SARMs has been considered doping by the US Anti-Doping Agency (USADA), and these drugs are on the World Anti-Doping Agency (WADA) prohibited list [R].
Andarine should be avoided if you are in competitive sports as a professional athlete.
This drug is not approved by the FDA for any purpose. Legally, it still falls somewhere in a gray zone and is available as a supplement.
Users can purchase andarine as a supplement.
There is no set dose for this drug, as there are no publicly available clinical trials. Most recommendations come from personal experiences on bodybuilding forums.
Common dosing range is 50 to 75 mg per day (divided into 3 doses taken with meals). Some recommend starting with lower doses of 25 to 50 mg per day, to decrease the risk of side effects. Andarine is often cycled.
This drug is not regulated, so the quality and even the identity of the product is often questionable. In a study of 44 products marketed as SARMs (including Andarine), only 52% actually contained SARMs and many were inaccurately labeled [R].
Limitations and Caveats
Andarine is a promising candidate for treating osteoporosis and muscle-wasting, but these benefits have not been explored in humans or the studies aren’t publically available. This drug was mainly tested in rats.
Although it is purchased and used as a supplement, its long-term benefits and risks in humans are unknown.
“Lost 2% of body fat in a month. The best part: I lost no weight. I actually gained a very respectable amount of muscle. Very thick, dense muscle. Increased vascularity. As for my training, strength increased on all major lifts. The other very noticeable increase was the amount of volume I could handle. And I never felt beat up the next day, just a bit sore, like I had done a good job. It was awesome. I will admit I did feel more sensitive to bright light. Sides went away immediately after I stopped using and during off days. This would really only be an issue if you are dosing every day at like 75mg or more.”
“The whole seeing everything yellow isn’t very appealing to most people…”
“If you can deal with the side effects this is a great product to help in a cut or recomp phase and I would recommend this without hesitation, just be careful on the 1st couple nights while using it if you have to drive somewhere.”
“It took a while to notice results with the dosing protocol I was following. Although I didn’t notice much in terms of effectiveness, I could tell it was working if I upped the dosage. Around week 3 I noticed some drying out and strength gains on my lifts. The biggest difference was my wife noticing the effects of the cut/recomp! I wasn’t on a strict diet or anything like that at the time.”
Although Aandarine is available online as a research chemical, we at SelfHacked advise against using this drug given that its safety has not been confirmed in humans.