3 minutes

Testosterone and aggression: what's the link?

By Nick Harland | Medically reviewed by Lauren Sien
testosterone and aggression

Testosterone and aggression. Two words that seem to fit together like hand and glove. So much so, in fact, that testosterone is sometimes referred to as ‘the aggressive hormone’

But for all testosterone’s associations with aggression, is it actually true that the two are linked? Time to take a deep breath, relax, and dive in.

What is aggression?

Before looking at the links between testosterone and aggression, it’s worth thinking about what we mean when we talk about aggression. 

According to the word nerds over at the Cambridge Dictionary, aggression is ‘spoken or physical behaviour that is threatening or involves harm to someone or something’.

Aggression can also play out in less direct ways, such as passive-aggressive behaviour. This isn’t direct aggression towards someone - it might instead be a simple unwillingness to be helpful or friendly.

The problem with measuring aggression

It’s important to understand what aggression is because it’s not something that can be easily measured. You couldn’t, for example, go to your local GP and get an aggression test alongside your blood test.

Instead, we normally try to measure aggression through subjective measures like surveys and questionnaires. Sometimes, aggression levels are self-reported. On other occasions, they’re observed by others. Whilst these can be a useful way of measuring aggression, they can never be totally accurate. They’re still subjective, and different people can perceive aggression levels differently.

It’s an idea supported by this study, which found that the observed aggression levels of participants were higher than their self-reported levels. After all, one man’s level 10 aggression could be another man’s level one.

Our fluctuating testosterone levels

It can also be tricky to measure your testosterone levels. This is because they tend to fluctuate depending on the situation.

We all have what you might call a baseline level of testosterone. This can fluctuate depending on environmental factors such as stress, competition, or exercise. But even measuring that has its own challenges. For instance, this study found that baseline testosterone levels were higher among prisoners who had committed violent crimes. However, the issue with this is that the stressful, competitive nature of prison life could have caused those heightened testosterone levels.

So what else could lead to an increase in testosterone levels? It could be something as simple as playing a game of football. It’s a competitive environment, and plenty of things could happen: a nasty tackle, a dodgy refereeing decision, or even just conceding a goal. Any of these events - as well as the simple act of doing some exercise - could increase your testosterone levels.

On the other hand, if you’re relaxing at home listening to Beethoven’s Symphony No. 9 then it’s unlikely your testosterone levels are going to go through the roof. Unless you really hate classical music, that is.

Although stressful and competitive situations can increase testosterone levels, it’s still unclear whether that leads to more aggressive behaviour.

Testosterone and aggression: what the science says

A number of clinical studies have been carried out to find which links - if any - exist between testosterone and aggression. As of yet, there’s no evidence of any strong correlation between the two things.

One study did find that testosterone levels were higher in individuals with a history of aggressive behaviour. It also found that they rose during competitive or stressful situations. But the same study highlighted some issues with those results. The sample sizes were small, while self-reporting surveys and questionnaires are subjective and could never be 100% accurate. Interestingly, in a larger survey that involved more than 4,000 participants, the men who were administered testosterone did not report higher levels of aggression.

A later study tried to measure the links between testosterone and aggression with a bigger sample size. It also found a ‘weak positive’ relationship between the two things - i.e., no strong correlation.

Finally, this study found that testosterone treatment did not increase aggressive behaviour among its participants.

In fact, we couldn’t find any clinical studies which found a significant link between testosterone and aggression.

The numan take

There’s no evidence of any strong correlation between testosterone levels and aggression - partly because aggression is such a difficult thing to measure. Topping up your testosterone levels won’t make you scream at the ref on Monday nights, but it could help to regulate your mood, increase your energy levels, and improve your focus. It’s never a bad idea to keep things balanced.