Cellucor P6 Extreme Side Effects: My Experience

Cellucor's P6 Extreme is a popular supplement marketed as a natural testosterone booster. Here is a look at some of the potential side effects.

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As I approach the end of a cycle of P6 Extreme, I wanted to preface my full review of the product with a list of possible side effects from my own experience and from others cited online.

You can read my full review of the product here.

About P6 Extreme

P6 Extreme is said to be a natural testosterone booster. It is suggested that you take it for an 8-week cycle, and then stop taking it for 4 weeks. I am in the process of writing a longer review of the product as my 8-week cycle nears an end. Today, however, I am offering a preface to that review with some potential side effects reported for P6 Extreme. The official Cellucor website found here.


My Purchase

I went into a local GNC with the sole purpose of buying something to review – and decided to let the salesmen point the way. P6 Extreme was heavily touted by two salesmen behind the counter. They told me it was one of their hottest items, and the product was featured in a display next to the register. They claimed that it could lead to muscle gains as well as increased libido, and that customers had been reporting great success with the product. One of the salesmen told me he had used it for a full 8-week cycle and that his girlfriend liked what she saw when he was taking it.

I wasn’t sure if they pushed the product because they earn a commission on it (do they?) or if it really is one of their hottest sellers. With a price tag of $120, it’s certainly not in the price range for everyone. I took the bait with every intention of reviewing it here, and began taking it diligently.

As the salesman told me about muscle gains while using the product, I noted that I don’t currently lift heavy weights due to a recent shoulder injury. He said that the product would still help in a variety of ways.

A bottle of P6 Extreme contains 120 capsules. At 4 capsules a day, this is a 30-day supply. It retails for about $120, but a member discount will reduce that to about $108.

My P6 Extreme Side Effects

Below is a list of the side effects I personally experienced while taking P6 Extreme. I don’t know if these side effects are unique to just me, or if they are experienced by a large number of consumers.

  • Dry mouth. This was not as pronounced as other herbs, such as yohimbe, but I did feel an increased urgency to drink water.
  • Flatulence. Again, not extreme, but there did seem to be a slight increase in the early days of taking P6. This decreased over time.
  • Irritability. One might expect that an increase in testosterone would lead to increased irritability.
  • Sweating. In the first week of taking P6, I experienced increased sweating. This waned over the ensuing weeks.

All of the side effects above were minimal, and I did not experience them after the second week of taking the product.

Other Reported Side Effects

GNC readers give P6 Extreme generally favorable reviews, but a few reported aggression, irritability, and sleeplessness. The overall rating of the product on that site is 4 out of 5 stars.

To examine all possible side effects of P6, we would need to look at the possible side effects of the individual ingredients. Below is a list of most of the ingredients, along with their possible side effects.

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  • Ovine Placenta: There is little written about the side effects of ovine (sheep) placenta for human consumption.
  • Black cohosh, the second ingredient listed in P6, is called “Possibly Safe” by WebMD, with some unsubstantiated concerns about negative effects on the liver. Other possible side effects listed include stomach upset, cramping, headache, rash, and weight gain.
  • Beta-sitosterol. Rx List notes that this is generally safe but possible side effects include nausea, indigestion, gas, diarrhea, and constipation.
  • Wild Yam Root Extract. The American Cancer Society lists possible side effects as nausea, vomiting, and diarrhea. Rare allergic reactions can also occur.
  • Agaricus bisporus extract. Livestrong describes agaricus bisporus as “safe, nontoxic and well tolerated by the majority of the population.”
  • Stinging Nettle. Although used for hundreds of years and considered generally safe, stinging nettle does have occasional side effects as listed by the University of Maryland Medical Center. These include mild upset stomach, fluid retention, sweating, diarrhea, and rash.
  • Bayberry bark extract. This is the one ingredient which heralds the most warnings. WebMD describes it as “possibly unsafe” and states it may not be safe for anyone. Drugs.com lists it as “Moderate to serious danger.”
  • Salvia sclarea (also known as Clary Sage), there is little known about the safety of this product when used in quantities other than what is found in food. It is often used for upset stomach, so one may postulate that its inclusion here could be to offset possible side effects by other herbs in P6.

I would like to reiterate that a list of side effects does not mean that the product doesn’t work, or that any/all side effects may be experienced by everyone. Based on the list above, it would appear that stomach upset would be the most likely possible side effect associated with the ingredients of P6 Extreme.

In comparison to other herbs and supplements, I believe that the side effects of P6 Extreme are rather mild and it can be taken on an empty stomach.

A large number of users have reported positive results from P6 Extreme, which I’ll touch on further in my full review of the product. Other reviewers have reported no side effects at all. The few side effects I experienced were mild, and in no way has affected my overall opinion of the product.


Although I did experience a few side effects when taking P6 Extreme, most of these occurred in the first week of taking the supplement. Perhaps my biggest concern about the product is the inclusion of bayberry extract, as that herb receives some rather upsetting warnings. The warnings associated with that ingredient would be sufficient to make me take pause regarding P6 Extreme.

Read my full review after using the product for 8 weeks here.

Have you experienced any side effects while taking P6 Extreme? Let me hear from you in the comments below.