Does MK-677 cause Erectile Dysfunction?

MK 677 is one of the most popular SARMs on the market, but with many stories of it causing ED - is it really worth it?
Medically reviewed by Dr. Mohammed Fouda
Dr. Fouda uses his extensive knowledge and expertise as an academic scholar to medically review articles for scientific accuracy and credibility, ensuring that the medical information presented is up-to-date and trustworthy. He is responsible for ensuring the quality of the medical information presented on our website.

We often hear about athletes using PEDs to boost performance and muscle growth, all at the expense of some serious adverse effects. One of the biggest being erectile dysfunction or ED.

ED affects quite a lot of men, and while you may not realize it, is incredibly common in athletes who misuse or stop using certain PEDs. Usually, these PEDs mess with your endocrine system, however, there are rumors of MK-677 or Ibutamoren also causing ED.

Can growth hormone boosters cause ED, and is there a link between GH secretion and erections? What about natural growth hormones? Insulin-like growth factor?

Before we get too carried away, let’s look at the science and what others have experienced.

Warning: The content on and the information included in this article is intended for entertainment and informational purposes only. It is not intended nor implied to be a substitute for professional medical advice. Prior to buying anything, check that it is compliant where you live with your current government laws. We frequently mention research chemicals that are not made for human consumption. Therefore, before purchasing any product for personal use, consult with your doctor or healthcare provider first.

Key Takeaways

  • MK-677 can cause ED due to increased Prolactin
  • Vitamin B6 is the easiest and cheapest way to manage high Prolactin
  • HGH itself does not increase Prolactin
  • KM-677 can still be used to improve body composition

Does MK-677 cause Erectile Dysfunction?

Let’s jump right into the thick of it. Is there a biological chance that MK-677 can somehow mess with your ability to get a hard-on?

Yes, MK-677 can (by a chain of events) cause erectile dysfunction.

First off, it has nothing to do with the fact that an oral Growth Hormone secretagogue will increase Growth Hormone. MK-677 does not mess with your Testosterone levels, however, MK-677 does have the ability to mess with Prolactin (1).

Prolactin is described as “Prolactin is a hormone that’s responsible for lactation, certain breast tissue development, and milk production. Higher-than-normal levels of prolactin in your blood can cause certain symptoms, such as irregular periods, infertility, and erectile dysfunction.”

Prolactin is produced by the same gland as Growth Hormone – the pituitary gland. While it is technically possible that MK-677 can cause ED, it doesn’t happen too often.

Figure 1: Prolactin can’t just mess with your junk, but can influence all the other parts of your body too

Avoiding erectile dysfunction while on MK-677 is very easy, just use some Vitamin B6 at 100 – 300mg per day and you should be good! Vitamin B6 is known to keep Prolactin and Progesterone in check (2).

But before you do, I’ve gathered some stories about MK-677 and changes in Libido.

Stories about MK-677 and Erectile Dysfunction

“I’m 19yo started taking 15mg of Mk677 on February 18, met up with a girl a few days later, and had sex and it was all good. Next weekend I see that girl again and my dick just doesn’t work, I can’t maintain an erection. I started taking 100mg of P5P and 2 weeks later I met up with the same girl and I still went soft mid-way through sex.

PLEASE HELP Idk what to do, I’m still very horny sometimes (usually in the morning. I also think it’d be partly because I’m not as attracted to this girl. I just don’t feel the connection. I take it every day before bed.”

Reddit user

“All right, so two months ago I stopped taking mk677 since I ran out of bottle. Then I thought might be a good think to cycle it a little bit and wait 2-3 weeks before taking it again…… But then I kinda noticed that I’m having trouble keeping an erection or having a low libido towards my girlfriend which is pretty hot in my opinion…… I’ve seen that mk677 could cause gyno and Ed….. let’s say I’ve got ED, which isn’t 100% sure, is it possible for me to have only Ed and not gyno? Also, I’ve seen that b6 vitamins also known as p5p could help me with that, will I have to take these pills for the rest of my life to keep my prolactin level lower or just a couple time will make it ? Thank you all.”

Reddit user

Does Human Growth Hormone Cause Erectile Dysfunction?

Just for reference sake, what if you were to use the real deal, would Human Growth Hormone cause ED? Since HGH would not stimulate the pituitary gland, you’d expect it not to do anything, surely?

Using certain types of HGH replacement can cause ED, but they are not pure HGH and are all Growth Hormone Releasing Peptides, Hormones, or Secretagogues.

Since all of these will stimulate the pituitary gland to produce more HGH, it will also increase the production of Prolactin.

So no, pure HGH injections do not seem to cause ED.

What is MK-677?

When treating someone who is suffering from Growth Hormone deficiency, you have a few different routes to take. The easiest (and most expensive) is going to be simply using exogenous Growth Hormone.

Scientists realized this might not be accessible to everyone, and wanted something that’ll increase Growth Hormones in the body without costing several hundred dollars per month.

What they came up with were GHRPs, GHRHs, and something called MK-677. MK is known as a SARM but isn’t a SARM. It will interact with the Ghrelin receptors and cause an increase in Growth Hormone release from the pituitary gland (3).

Figure 2: By increasing the amount of GH in the body we can see massive physiological changes due to changes in metabolism and increased IGF-1 levels

Growth hormone deficiencies can be treated with this effectively, however, it can also be used for various other applications. The sports world soon realized this and using MK-677 for the benefit of increased HGH levels soon became quite popular.

Benefits of MK-677

All the benefits of MK-677 can be attributed to increased Growth Hormone and Insulin-Like Growth Factor 1 [4, 5].

  • Increase lean body mass
  • Decrease fat mass
  • Increase bone density
  • Improve sleep quality
  • Increased sexual function
  • It can cause cortisol suppresses factors to increase
  • Improved cognitive function

Side Effects of MK-677

For all its benefits, there will, unfortunately, always be a drawback. Primarily, this will be due to an increase in HGH:

  • An increase in GH levels can cause insulin sensitivity issues
  • Water retention
  • Edema
  • A potential increase in Prolactin
  • Prolonged oral treatment of MK-677 can lead to a Magnesium shortage in the body

Where to buy MK-677?

Finding a retailer that is open about its products is key. Without transparency about testing, etc, you are just shooting in the dark.

Your best bet for MK-677 is going to be Sports Technology Labs, as they not only sell MK-677 but also Peptides that can increase GH levels as well – such as Ipamorelin.


MK-677, or Ibutamoren Nutrobal, is not a steroid, nor is it technically a SARM. It is what isΒ known as a selective agonist.

An agonist is a chemical that can bind to receptors in the body. It then reprograms the receptor, encouraging it to produce a natural physiological response.

A selective agonist is a chemical that only binds to certain receptors. In this instance, the receptors it binds to in the body are largely responsible for muscle growth and repair and weight management.

It is a non-peptide agonist which works on the ghrelin receptors and those responsible for growth hormone production and secretion.

On some black markets, it is sold as a SARM, but in reality, it isn’t. It may behave like a SARM and it may be very similar to a SARM, but it most certainly isn’t a SARM.

Mk-677 is currently still being studied about its medicinal properties, as it is designed to serve as a medication for people suffering from GH deficiencies.

This compound was created by a company known as Reverse Pharmacology. Initially, it was first designed to help treat people suffering from osteoporosis, along with muscle-wasting diseases, and those suffering from obesity.

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β€οΈβ€πŸ©Ή Side Effects: Water retention and gyno
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  • Better recovery
  • Improved fat loss
  • Massive muscle gains
  • Water retention
  • Gyno

They also stock SARMs and other Peptides that can aid in protein synthesis and fat loss, both helping with body composition.

What is Erectile Dysfunction?

Erectile dysfunction is a scenario where the male or person with a penis fails to either achieve or maintain an erection for sexual intercourse. They will have the libido to want sex, however, the poor sexual function keeps them from actual penetration.

Erectile dysfunction usually only affects older men, however, with Testosterone levels falling in the general public, it is more common than ever before. Healthy young adults will suffer from ED and there might not even be an obvious reason for it, however, there are some factors such as environmental impacts people fail to consider.

Causes of Erectile Dysfunction

ED isn’t always diseases related, there are various reasons why someone could be suffering from ED:

  • Hormonal imbalances
  • Emotional reasons
  • High blood pressure
  • Obese patients often suffer from ED
  • Porn and drug abuse
  • High estrogen and prolactin

Cures for Erectile Dysfunction

  • If the cause is porn or mental issues, you would need psychological help
  • PT-141 has been shown to improve sexual function
  • Melanotan-II can help with erections as well as having significant benefits for fat loss and skin tone
  • Viagra and Cialis both work
  • Living a healthier lifestyle could also help (losing body fat, increasing fat-free mass, etc)

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Conclusion: MK 677 Erectile Dysfunction, is there a connection?

There does seem to be a connection after all. We know that Growth Hormones can have tremendous health benefits, however, it does seem to have side effects. Sure, bone health improves massively, but insulin resistance is a bitch.

MK-677 can help you with Growth Hormone GH release, and this can lead to improve sleep quality, improve cognitive function, etc. However, it can cause an increase in prolactin levels in the body.

Increased prolactin or progesterone levels can lead to some issues with libido, even in healthy young adults! Thus, you must keep track of your blood work to ensure you don’t get caught off guard. Vital hormones should be kept in range, and this includes progesterone.

Tip: Vitamin B6 manages Progesterone cheaply.

FAQs about MK-677

What happens if you take too much MK-677?

The side effects of MK-677 are pretty minimal, and you shouldn’t be in too much trouble. If you continue to take too much over a long period, you can start running into issues of insulin resistance and weight gain – and not the good kind.
This is easily managed by taking less MK, exercising more, and perhaps using something like Metformin.

Does Ibutamoren mess with Testosterone?

No, it does not. MK-677 will only interact with receptors that lead to changes in GH secretion, not Testosterone. Keep in mind that MK-677 can lead to an increase in Prolactin, which can have side effects if not managed properly.

Does MK-677 suppress Testosterone?

No, it does increase Prolactin though.

MK-677 and Cancer

There is a chance that MK-677 could worsen or increase the risk of cancer. See, MK-677 will increase Growth Hormone levels in the body, which will directly lead to an increase in IGF-1 levels. IGF-1 is one of the growth factors of the human body, including cancer cells.

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Daniel Louwrens BSc PT

Daniel Louwrens BSc PT | Writer

Daniel Louwrens is a well-rounded fitness professional with over 10 years of experience in bodybuilding and fitness. He holds a BSc in Chemistry from the University of Western Cape and is a certified International Personal Trainer and Nutritionist. He is also a skilled bodybuilder and head coach for Muscle and Brawn. With his knowledge and expertise, he provides personalized training, nutrition, and recovery guidance to help clients reach their fitness goals.

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Dr. Mohammed Fouda

Dr. Mohammed Fouda | Reviewer

Dr. Fouda uses his extensive knowledge and expertise as an academic scholar to medically review articles for scientific accuracy and credibility, ensuring that the medical information presented is up-to-date and trustworthy. He is responsible for ensuring the quality of the medical information presented on our website.

Read all articles
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