There are a lot of myths around the benefits of taking cold showers, that’s not to say that there are no benefits, but they are lauded far beyond what they actually do. And it seems that people using cold showers to raise testosterone are likely to be sorely disappointed.
There is some truth in that the temperature of the testes does impact testosterone production and there are some benefits of cold showers that could reduce some symptoms of low testosterone. Which is possibly where this myth has come from, but as to whether or not cold showers raise testosterone levels, sadly the answer seems to be no.
The Research On Cold Showers For Testosterone And How They Affect The Symptoms
The first element of this is that cold temperatures have been shown to improve sperm quality and volume, as a result men typically have better quality sperm during winter  and this has be shown in studies dating back to the 80s.  Thus potentially helping alleviate some of the fertility issues associated with low test levels. One study even suggested limiting exposure to warm water raised sperm counts by 500% .
Cold showers have also been shown to boost energy levels, which is pretty much anecdotally known by most people without the studies . And if you consider that low energy is a symptom of low test we can see how this could be helpful and why people think cold showers boost testosterone levels.
There are some studies that suggest they boost metabolism, although these are a little washy (yes the word choice was deliberate). And there are some studies that suggest cold showers can improve recovery after a workout, but there are as many that showed no improvement. But, those who do get this benefit are going to report increased recovery, again, a low test issue symptom.
The main benefit of cold showers, seems to be that it boosts immunity, most of the studies agree on this with some showing that sickness absence dropped 30% for people who took cold showers, and another that cold showers release adrenaline  which in turn kick starts you immune system.
Studies That Show Cold Showers Don’t Raise Testosterone Levels
There are two main studies done to test the question, do cold showers raise testosterone levels, the first, showed no signs of change  and the second actually showed a short term lowering of test levels as a result. 
Do cold showers raise testosterone in any other way?
Burning Fat (Beyond Weight Loss)
There are some studies that suggest that taking a cold shower first thing in the morning can kick start the metabolism and break down of brown adipose tissues, this gets the body into a state where it burns fat for energy and stablizes serum glucose (blood sugar levels) throughout the day, however most of these studies are currently on animals, although as it is known to raise enorphins, require calories to heat the body amongst other things, it seems likely that this will transfer to human studies as the mechanisms are well documented to be similar.  This is unlikely to be enough to relieve weight gain from low testosterone levels, however, it is a benefit. It should also be noted that reducing your body fat percentage if overweight does raise testosterone.
There are a few other ways that cold showers can alleviate the symptoms of low testosterone and potentially help. For example, taking a cold shower for up to 5 minutes 2 or 3 times a week has been demonstrated to raise endorphins which in turn relieved symptoms of anxiety stress and depression. Raised cortisol levels can lower test levels, so in a round about way this would mean that cold showers raise testosterone in these specific cases.
Do cold showers lower testosterone?
There is one way in which having a cold shower could notably make testosterone levels worse, and that's if you have one before bed, whilst it has been suggested that cool showers before bed can be beneficial in tricking your body into thinking it's time to go to sleep as temperatures decline in the evening, a completely cold shower is likely to cause a cortisol spike. Increasing the stress hormone before bed can lead to poorer sleep which does harm to testosterone levels.
How You Can Raise Your Testosterone Levels Naturally
However, there are ways to raise your testosterone levels naturally. The most easy to deal with are:
- Sleep More
- Lose Weight (if you’re overweight)
- Ensure Your Not Vitamin Deficient (Notably Zinc and Vitamin D, these can lower test levels between 30-90%)
- Reduce Stress
- Herbal Compounds (There are a couple that have shown consistent clinical results)
1 - https://doi.org/10.1016/j.ajog.2013.02.010
2 - https://doi.org/10.3109/01485018808987051
3 - https://www.ncbi.nlm.nih.gov/pubmed/17335598
4 - https://doi.org/10.1152/ajpendo.00691.2006
5 - https://dx.doi.org/10.1073/pnas.1322174111
6 - https://www.ncbi.nlm.nih.gov/pubmed/1890772
8 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6131648/