What we know about usnic acid:

Since the rise of usnic acid as a fat loss supplement, many disputes have taken place as to the safety of this product. In fact, it seems the entire elite fitness board and others have labeled usnic acid as more dangerous than DNP. Because of this, I am writing this article in an attempt to shed some light on the factual information we currently have at the moment. First I would like to address the two main studies which have been used as evidence to support that usnic acid is dangerous.

Study 1:

J Ethnopharmacol 1991 Jul;33(3):217-20 Related Articles, Books,

Mitodepressive, clastogenic and biochemical effects of (+)-usnic acid in mice.

al-Bekairi AM, Qureshi S, Chaudhry MA, Krishna DR, Shah AH.

Experimental Animal Care Centre, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.

Mice were treated orally with aqueous suspensions of (+)-usnic acid in a single dose of either 100 or 200 mg/kg. The effects on femur cells and proteins and on nucleic acids of liver cells were studied 24-72 h after treatment. (+)-Usnic acid was found to affect the proliferation of polychromatic erythrocytes possibly by interference with RNA biosynthesis. The slight increase in the micronucleated polychromatic erythrocytes without affecting DNA synthesis suggests an effect of usnic acid on spindle apparatus.

This study has caused a lot of debate as far as the extent to which usnic acid is cancerous. In reality, it seems that most people do not understand the results of this study and are blowing the slight clastogenic effects out of proportion.

That article is simply a report of the results of a standard Mouse Micronucleus test. It demonstrates some (slight) degree of clastogenic (chromosome-breaking) activity in laboratory animals. While clastogenicity was demonstrated by the increase in micronucleated (immature) red blood cells in the one mouse micronucleus test to which he referred, UA does not cause point mutations, as shown by the negative Ames test (Ames test screens for point mutations, micronucleus test screens for clastogenicity). Neither test comes close to proving cancer-causing ability, and neither has a THING to do with liver toxicity.

Of the two studies, this is the only one that actual appears to have relevance on the surface. Hopefully based on the above explanation, one will realize that this study is no basis for alarm. If one wants to make a better assessment, they could try sub chronic oral toxicity studies in rats and mice, and a chronic toxicity study in transgenic mice. They're just two of a number of standard toxicology studies that my employer performs, but they're not cheap. However, they will provide better info for carcinogenic potential as well as a good look at any target organ effects.

The second study presented has been poorly represented and explained. As stated earlier, a reputable member of the elite fitness board posted this study. At which time it became a sticky pronouncing the danger of usnic acid. No one came to the defense of usnic acid nor were many questions asked. As a result, we can speculate that the majority of people who read that posted were misinformed about the facts. As a side note, I personally tried to have a logical discussion with elite fitness moderator Mr. X about usnic acid. In an attempt to provide logical discourse, I presented the evidence as best I could. The next day, the thread was closed. In my opinion, this was rather unfortunate as I always believed the purpose of the message boards was to promote discussion. Regardless, here is the 2nd study that was presented on the leading bodybuilding boards. It was titled “Why Usnic Acid causes liver failure/cancer”

Study 2 WITH ADDITIONAL COMMENTARY BY macrophage69alpha, elite fitness moderator:

“Why usnic acid causes liver failure/cancer...

UA is generally a much weaker uncoupler than DNP.. HOWEVER THERE ARE VERY UNPLEASANT EXCEPTIONS..

This study bodes very ill for the use of usnic acid and the link to liver failure/cancer..

UA requires 1/50 the dose to cause complete halt of oxidative phoshoralation in the liver as compared to DNP...

interesting that the users of LIPO-k have liver failure.”


1: Nat Toxins 1996;4(2):96-102 Related Articles, Links

Lichen acids as uncouplers of oxidative phosphorylation of mouse-liver mitochondria.

Abo-Khatwa AN, al-Robai AA, al-Jawhari DA.

Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.

Three lichen acids-namely, (+)usnic acid, vulpinic acid, and atranorin-were isolated from three lichen species (Usnea articulata, Letharia vulpina, and Parmelia tinctorum, respectively). The effects of these lichen products on mice-liver mitochondrial oxidative functions in various respiratory states and on oxidative phosphorylation were studied polarographically in vitro. The lichen acids exhibited characteristics of the 2,4-dinitrophenol (DNP), a classical uncoupler of oxidative phosphorylation. Thus, they released respiratory control and oligomycin inhibited respiration, hindered ATP synthesis, and enhanced Mg(+2)-ATPase activity. (+)Usnic acid at a concentration of 0.75 microM inhibited ADP/O ratio by 50%, caused maximal stimulation of both state-4 respiration (100%) and ATPase activity (300%). Atranorin was the only lichen acid with no significant effect on ATPase. The uncoupling effect was dose-dependent in all cases. The minimal concentrations required to cause complete uncoupling of oxidative phosphorylation were as follows: (+)usnic acid (1 microM), vulpinic acid, atranorin (5 microM) and DNP (50 microM). It was postulated that the three lichen acids induce uncoupling by acting on the inner mitochondrial membrane through their lipophilic properties and protonophoric activities

“THIS "supplement" is VERY UNSAFE

’Complete shutdown of oxidative phosphoralation causes liver failure, the inhibition even seen with lower doses causes tremendous amounts of free radical damage as well as impairing liver function which in those susceptible MAY lead to early/rapid expression of liver related cancers.’”

The study posted is valid, but is not relevant by any means. All it says is that Usnic Acid WORKS. It is indeed an uncoupler, and the study cited proves it. Uncouplers can shut down the liver completely if OVERDOSED.

The study cited looks at the concentrations of UA or DNP at the target site (liver mitochondria) which cause complete shutdown of OP. In the study cited, UA did so at 1/50th the concentration of DNP. But to correlate this to dosages taken orally, one has to consider basic issues in absorption and transport to the liver mitochondria. I doubt that DNP and UA are completely identical in such regards. So one could not simply say that you should take 1/50th as much UA as you would DNP for the same degree of biological effect, and of course you couldn't say anything about such effects in any other organ, at least not based on this study. In addition, many consumers take a usnic acid dosage well over a normal DNP dosage and liver failure has not been a concern by any means. This fact alone shows the fallacious nature of this comment.

UA does what it is claimed to do, at least in mice under the conditions of the experiment reported. As with the biological effects of a myriad of other biologically active substances, from certain vitamins to most prescription drugs, at the proper dose it can produce a desired effect and yet in excess, it can prove fatal.

Here is what we know through experience. Some users of UA/SU have reported the following:

1. Rash – Some users develop a rash on usnic acid and sodium usniate. This appears to an allergic reaction to some substance within usnic acid. What we have witnessed is that the rash is mostly present in higher dosages – usually above 750mg. In addition, the rash has subsided in all people who have reported the rash. For some it took a few days, others around 2 weeks to completely subside.

2. Heat and increased sweating – this is the most commonly reported side effect of usnic acid. The heat stops as usage stops and is simply a by-product of the way usnic acid works in your body.

3. Headaches – some people have reported headaches. This could very well be a result of the increased heat and potentially dehydration from increased sweating.

4. Vomiting – 2 or 3 people reported vomiting while taking usnic acid. This tends to be a rare occurrence as far as we know.

5. Elevated enzyme levels – A couple people checked their liver enzyme levels via a blood test and found their levels to be above normal (in one situation, quite high actually). While only a few people have checked their levels, it seems that usnic acid might indeed cause some strain on the liver. Just as 17aa orals are liver toxic and other supplements can raise blood pressure, cause prostate hypertrophy, and other sides, this might be one side effect of usnic acid use. I should point out that it is recommended that usnic acid be cycled (2 weeks at time) to give your liver sufficient recuperation time if it is indeed being strained.

6. Abdominal pain – I have only witnessed this from a few users. This tends to be rare as well.


There needs to be an understanding that simply because a product is over the counter, does not mean that it can be abused. Usnic acid is powerful and effective, yet needs to be treated with respect, just like any other supplement you might take. For some reason, people having been making a huge fuss over usnic acid and the truth is that we have yet to see any intelligent arguments made as to why usnic acid is a horrible supplement so long as it is dosed properly. I hope that through the information presented above, one will see that usnic acid has not been shown to be any more “dangerous” than an ECA for example. The interesting thing about products containing ephedra is that according to the FDA, over 800 injuries have been reported by users and doctors to the FDA and various state medical bodies, including more than 50 deaths. Most of these cases involve the heart attacks or high blood pressure leading to bleeding in the brain or stroke.

Does this mean we should stop using ECA’s? In my opinion no. The objective here is not to present evidence against ephedra. In fact, I think it is effective and safe when used correctly. The key phrase in the previous sentence was, “when used correctly”. What I am trying to say is to take caution when using any supplement for it seems to be the trend that for any effective supplement, there will be people with adverse reactions. The same goes for prescription based drugs as well. Next time you view a commercial on TV for a prescription drug, listen to the words at the end that usually state, “side effects include: nausea, dizziness, diarrhea, nose bleed, etc.

Clearly, the side effects witnessed with usnic acid use are not beyond the normal range witnessed with many other effective supplements. In addition, much of the hype and hysteria should now be reduced based on the explanations to the misrepresented studies above. Lastly, I would like to point out that I do not claim to be a doctor, expert, or scientist. I, however, have done the research on the information available of usnic acid and these are the conclusions we can LOGICALLY make at this point in time. I think it is important for people to continue to post their experiences so that more information can be gathered on usnic acid. This information is extremely valuable for the continuation of the learning and education process regarding usnic acid.

If you are interested in using usnic acid, the following advice should help to make your cycle more successful:

1.As stated earlier, usnic acid may put strain on the liver. Using ALA will help if this is a concern to you (Vitamin C, E, and magnesium should help as well).

2.Only run a 2-week cycle. Users have reported a decrease in fat loss after week 2, and if UA does indeed put strain on the liver, it is a good idea to cycle the product.

3.Drink a bunch of water each day. This is a good recommendation no matter what your doing.

Special thanks to DaddyR for helping with much of the analysis. If you have questions, feel free to contact me at usnicacid@bdcnutrition.com or PM me.

Thank you.