Ostarine
OTHER NAME(S): enobosarm, GTx-024, MK-2866, ostarine, OTR-AC, S-22
Overview
Ostarine, a selective androgen receptor modulator (SARM), is sometimes used to improve athletic performance, although its benefits are not well defined. Common side effects include headache, sleep problems, fertility problems, and nausea. Serious side effects include heart attack, stroke, liver damage, hallucinations, psychotic-like behavior, or sexual problems. In the U.S., ostarine is an unapproved drug, which means that it cannot be legally sold as a dietary supplement. But it may be found in some products that are marketed for athletic performance, even if it is not on the label. Talk with your health care provider before starting any performance-enhancing supplement.
Uses
What is ostarine used for?
Ostarine may be used to improve athletic performance and build muscle, but its benefits and risks are not well defined.
Note: Ostarine is not approved by the FDA for any use. The FDA also does not consider ostarine to be a legal dietary ingredient in the U.S. Learn more about the legal status of ostarine here.
How does ostarine work (mechanism of action)?
Ostarine is a type of chemical called a selective androgen receptor modulator (SARM). It is made in a lab and designed to have some, but not all, of the same effects as testosterone, a sex hormone that is naturally made by your body. This means that it may have some of the same effects and side effects as testosterone. But it is not exactly the same as testosterone, and its safety and benefits are not well defined.
In the U.S., ostarine is an unapproved drug that is being studied for various reasons. Some people have had serious health problems after taking ostarine.
How should I store ostarine?
You should store ostarine according to the product label. Most ostarine products should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.
Side Effects
What are the most common side effects of ostarine?
The most common side effects of ostarine are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.
- Headache
- Infertility
- Nausea or upset stomach
- Sleep problems
There may be other side effects of ostarine that are not listed here. Contact your health care provider if you think you are having a side effect. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of ostarine?
While less common, the most serious side effects of ostarine are described below, along with what to do if they happen. The effects of taking ostarine long-term are unknown.
Severe Allergic Reactions. Ostarine may cause allergic reactions, which can be serious. Stop taking ostarine and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching or skin rash
- Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Hallucinations or Psychotic-Like Behaviors.Ostarine may cause hallucinations or psychotic-like behaviors. Tell your health care provider right away if you have any of the following symptoms or have been told by others you have these symptoms.
- Hearing, seeing, smelling, tasting, or otherwise perceiving things that others do not
- Delusional thoughts, such as false beliefs that you are being controlled
- Disorganized thoughts, such as jumping between topics or having a hard time focusing
- Sudden decline in self-care, such as personal hygiene or academic/work performance
- Aggressive behavior
Heart Attack and Stroke.Ostarine can increase your risk of a heart attack or stroke that can lead to death. This risk is higher in people who already have heart disease or who regularly use ostarine. If you have had a recent heart attack, taking ostarine could increase your risk of having another heart attack. Get emergency help if you have any of the following symptoms of a heart attack or stroke.
- Chest pain or pressure
- Fast or abnormal heartbeat
- Trouble breathing
- Pain in your back, jaw, throat, or arm
- Sweating, upset stomach, vomiting, or dizziness
- Sudden weakness on one side of your body
- Sudden and severe headache
- Slurred speech or trouble understanding speech
Liver Damage.Liver damage, also called hepatotoxicity, can happen when taking ostarine. Call your health care provider right away if you have any of the following symptoms of liver damage.
- Nausea or vomiting
- Stomach or belly pain
- Fever
- Weakness or unusual tiredness
- Itching
- Loss of appetite
- Light-colored poop
- Dark-colored urine (pee)
- Your skin or the whites of your eyes turning yellowish (also called jaundice)
Sexual Problems.Ostarine may cause sexual problems. Tell your health care provider if you have any of the following sexual problems.
- Decreased sex drive
- Delayed ejaculation or unable to have an ejaculation
- Problems getting or keeping an erection
- Delayed orgasm or unable to have an orgasm
Precautions
Who should not use ostarine?
Allergies to Ingredients. People who are allergic to any of the following should not take ostarine.
- Enobosarm
- GTx-024
- MK-2866
- Ostarine
- OTR-AC
- S-22
- Any of the ingredients in the specific product
Your pharmacist can tell you all of the ingredients in the specific ostarine products they stock.
Pregnancy.Do not use ostarine if you are pregnant. If you become pregnant, contact your health care provider right away. See the Pregnancy section for more details.
What should I know about ostarine before using it?
The FDA considers ostarine to be an unapproved drug, which means it cannot be legally sold as a dietary supplement. However, ostarine products may still be available for purchase in many places. These products are not regulated and have not been tested to confirm that they contain the ingredients stated on their labels.
Keep ostarine out of the reach of children.
Ostarine is prohibited by the World Anti-Doping Agency (WADA) for use by athletes, whether they are in or out of competition. Learn more about the WADA Prohibited List here.
Ostarine may make it hard for you to get your partner pregnant (infertility). It is possible that this may continue even after stopping ostarine. If this is a concern for you, talk to your health care provider before taking ostarine.
Some dietary supplements that are marketed for athletic performance have been found to contain unapproved ingredients, such as ostarine. Use caution when buying any products marketed for athletic performance because they may contain harmful ingredients that are not listed on the label. Find a list of potentially harmful products from the FDA here.
What should I tell my health care provider before using ostarine?
Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if ostarine is right for you.
In particular, make sure that you discuss any of the following.
Other Current and Past Health Conditions.Tell your health care provider if you have any of the following.
- Cancer
- High blood pressure
- Heart problems
- Kidney or liver problems
- Mental health problems, including mood changes, hallucinations, paranoia, or psychosis
- Prostate problems, including an enlarged prostate or benign prostatic hyperplasia (BPH)
Other Medicines and Supplements.Ostarine may interact with other medicines and supplements. Before taking ostarine, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.
Pregnancy. Ostarine may cause harm to a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.
Breastfeeding. It is not known if ostarine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.
Interactions
Does ostarine interact with foods or drinks?
There are no known interactions between ostarine and foods or drinks.
It is unknown if drinking alcohol will affect ostarine. But your risk of liver damage may be higher if you drink alcohol while taking ostarine.
Does ostarine interact with medicines (drug interactions)?
Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are using any of the following before taking ostarine.
- A blood thinner, which is a medicine used to treat or prevent blood clots
- Probenecid, which is a medicine commonly used for gout
- Estrogen or progesterone, which is a hormone found in certain forms of birth control or hormone replacement therapy
- Testosterone, which is a hormone used to treat low testosterone levels caused by certain conditions
- Any other medicine that contains hormones
Some medicines may alter the blood levels of ostarine. Tell your health care provider about all medicines that you take or have recently taken.
The interactions between ostarine and medicines are not fully understood. As with most unapproved products, the research on drug interactions with ostarine is incomplete. Always check with your health care provider before taking ostarine with any medicines.
Dosing
What should I do if I accidentally use too much ostarine?
If you or someone else has used too much ostarine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
Ostarine is an unapproved drug that cannot be legally sold as a dietary supplement in the U.S. It may be found in some products marketed for athletic performance, even though it is not listed on the label. Ostarine may cause serious side effects in some people. Speak with a health care provider before taking ostarine for any reason.
References
- Investigational New Drugs: “Pharmacokinetic drug interactions of the selective androgen receptor modulator GTx-024 (Enobosarm) with itraconazole, rifampin, probenecid, celecoxib, and rosuvastatin.”
- Journal of Cachexia, Sarcopenia and Muscle: “The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial.”
- National Cancer Institute (NCI Drug Dictionary): “enobosarm.”
- Operation Supplement Safety: “SARMs: What’s the harm?”
- U.S. Anti-Doping Agency (USADA): “Substance Profile: What Athletes Need to Know About Ostarine.”
- FDA: “FDA warns against using SARMs in body-building products,” “FDA Warns of Use of Selective Androgen Receptor Modulators (SARMs) Among Teens, Young Adults.”