Truth about Test Flu

“Test flu” is a term used to describe a set of symptoms that are sometimes experienced by individuals who are taking AAS, particularly Testosterone. The condition is characterized by flu-like symptoms, including fatigue, fever, muscle aches, joint pain, and headache.

The onset of test flu typically occurs within a few days of starting anabolic steroid treatment, although it can sometimes take longer to develop. The symptoms can range from mild to severe and may last for several days to a week or more.

The exact cause of “Test Flu” is unknown, but there are 3 main possible reason why it occurs. In this article, we will go over those 3 reasons and explain how to deal with them as effectively as possible.


One theory behind test flu is that the body’s immune system is triggered by the introduction of a foreign hormone that the body has never dealt with before. This can cause a general immune response, which can lead to the flu-like symptoms.

Thankfully, Test Flu tends to subsist after a few days (some times a week or even two in the worst case scenario) after the body has adapted to the foreign hormone(s), so the solution is to push through it.

NOTE: This can ONLY be the cause of “Test Flu” for first time users. If you ran a cycle without problems before you ever got Test Flu, chances are the cause is one of the following…


This second reason is quite common and occurs as a result of buying low quality underground gear. Low quality labs do not manufacture their gear in perfectly sterile environments, so it is possible for impurities to get into a vial and cause an adverse reaction once injected (which can either manifest themselves as a flu or even worse, as an infection).

If you have been using a specific brand of gear with great success and one day you decide to change, only to experience flu symptoms after your first shot with the new brand, chances are that brand is not as good as the first one you used, so you should ditch it immediately.


This reason is often overlooked but in my opinion the most common reason for “Test Flu”. Some underground labs suspend their AAS raws in synthetic carrier oils (vs the sterile natural oils that pharmaceutical companies and high-quality underground labs use) which can cause adverse reactions and inflammation in some users.

The most commonly used synthetic oil in AAS formulations is Ethyl Oleate. When buying AAS, make sure you are buying from a source that does not use it in their formulations. Interestingly, pharma-grade Testosterone manufactured in Spain also includes this harmful synthetic oil, so avoid it at all costs.

Outside of Spain, all pharmaceutical-grade companies and reputable underground labs use organic carrier oils like Cottonseed Oil, Grapeseed Oil, Olive Oil, Castor Oil and others.

Stick to companies that use the aforementioned carrier oils to prevent adverse reactions and systemic inflammation.


To conclude, you need to make sure you are getting your gear from the best possible source. If you are buying from a good source and you still get the Test Flu the FIRST time you pin a specific compound, chances are it’s your body adjusting to it and the symptoms will subsist in due time.

Steroidify carries the most well-known and reputable brands in the space, so do not hesitate to check out our website to find everything you could possibly need.

William Davis

William has been studying and experimenting with bodybuilding pharmacology for over 6 years. After being an independent researcher for all these years, he has decided to share his knowledge with the bodybuilding community through his science-based articles. His approach to enhanced bodybuilding can be summed up in the saying “less is more”, as he believes that prioritizing harm mitigation and looking for ways to maximize the positives is the key to longevity in bodybuilding.

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