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Can MK-677 Cause Erectile Dysfunction & How to Prevent it

Can MK 677 cause erectile dysfunction & how to (easily) prevent it

If you’ve been reading about SARMs and research chemicals you might already know that some have the potential to cause sexual side effects due to endogenous testosterone suppression.

Even though MK 677 is not a SARM and does not suppress testosterone, you might have run into users online claiming it caused erectile issues for them.

On paper MK 677 can cause erectile issues because it increases prolactin. But in reality, erectile issues from it are extremely unlikely and rare.

The rest of this article will be the long answer, provide you with preventive measures, and answer any questions you may have regarding MK 677 and ED.

Everything you’ll read is strictly based on the latest academic data and the analysis of thousands of anecdotal reports and experiences. Enjoy!

Does MK-677 Cause ED

MK-677 will increase your prolactin levels. Prolactin is the hormone responsible for milk production in females. In men, high prolactin can cause gynecomastia, low sex drive, and even erectile dysfunction. So how much of a risk factor is taking MK-677?

In a clinical study on MK-677 by the Journal of Bone and Mineral Research, healthy and functional elderly adults were given 25 mg/day of MK 677 for 2-9 weeks.

By the 9th week, their serum prolactin increased by 27%.

Though right after the discontinuation of treatment with MK677 it returned to baseline.

While a 27% increase sounds like a lot, it is not high enough to cause erectile dysfunction or erectile issues by itself. Especially in young and healthy men. Not to mention that most users do not take 25 mg/day, but are closer to 10 mg/day.

From this we can conclude:

Even though extremely rare, erectile dysfunction with MK 677 is still possible in men that have low testosterone levels, high prolactin levels, and a history of erectile issues. This means that men already prone to erectile issues, run the risk of exacerbating them by taking MK-677.

If you fall into this group and are concerned, you can be 100% on the safe side of things by getting bloodwork done and testing your prolactin and testosterone levels. If your baseline is within the reference range, you will not experience any prolactin-related side effects.

Preventive measures in the following section.

In my opinion, you should not be taking SARMs or other RCs like MK-677 unless your hormone markers are in check. That defeats the whole purpose of preserving longevity and optimal PED use.

Side Effect Mitigation Protocol

Preventing issues before they arise is much easier than dealing with them afterward. And fortunately, preventing erectile dysfunction while on MK 677 is very simple.

It comes down to reversing the increase in prolactin, which can be easily done by supplementing with:

  • Vitamin B6 in the form of P5P – 100mg before bed every day during your MK 677 cycle

Even though the risk of ED from MK-677 is incredibly small, do this even if you aren’t prone to ED as this amount of P5P will have a good impact on your sleep quality without any negative side effects.

If you fall into the group at risk, start with a small dose of MK 677 and slowly increase it whilst actively monitoring for prolactin-related side effects.

Real Cause of Erectile Dysfunction

I believe that the majority of erectile dysfunction reports from MK 677 are because of a fake product.

Unfortunately, while it’s not as common as it was a few years ago, many companies still sell fake MK 677 and cut corners whenever they can despite it being one of the cheapest RCs to manufacture.

P.S. Make sure the MK677 you’re getting is legit. These are my recommended sources for the highest-quality goods available:

  • US – Discounted Prices: “POP10” (Highest Possible)
  • EU – Discounted Prices: “POP20” (Highest Possible)


Erectile dysfunction from MK 677 is extremely rare and can only happen to people with very high baseline prolactin levels, low testosterone levels, and if the MK 677 is fake.

If you’re concerned and want to be 100% safe, you can go the extra mile to get your prolactin levels tested.

But supplementing with P5P during your MK 677 cycle will prevent ANY potential prolactin-related side effects, including erectile dysfunction.


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