The 4 different types of erectile dysfunction

Erectile dysfunction (ED) is when you have persistent trouble getting or keeping an erection firm enough for sex. It's extremely common, but not always straightforward to diagnose, because there are several types of erectile dysfunction, each with a different underlying cause.¹ Getting an erection depends on four things working properly: your mind, nerves, blood flow and hormones. ED can follow when any one of them doesn't.

1. Psychological causes

An erection starts in the mind. Sexual arousal triggers nerve cells in the brain, which tell the body how to respond. Sometimes ED happens because the mind doesn't set off that trigger, often down to relationship problems or psychological trauma.

Stress, depression, and anxiety can all interfere with your ability to get and keep an erection.¹ The two can also feed each other: the more severe the depression, the more severe the ED tends to be, and living with ED can worsen depression in turn.² Some antidepressants can cause ED as a side effect too, which is worth raising with whoever prescribed them.

Treatment depends on what's behind it. That might mean talking to your GP, therapy to work through trauma, or ED medication to help with performance anxiety while you deal with the underlying cause.

2. Nerve signalling

The second function an erection depends on is nerve signalling. This is controlled by the central nervous system, which signals the body to relax the arteries and let more blood flow to the penis.

Nerve damage can be caused by injury, surgery, multiple sclerosis, Parkinson's disease, or diabetes (which affects blood vessel health as well as nerve health). If your nerves are perfectly intact, blood flow could be the issue instead.¹

3. Blood flow

Blood flow is critical for strong erectile function.¹ When you're sexually aroused, the central nervous system triggers an involuntary response: nerves signal the arteries to relax and widen, sending more blood to the penis. That's what produces an erection.

Most ED medications, including sildenafil, Viagra and tadalafil, are PDE5 inhibitors. PDE5 is an enzyme that breaks down the molecule responsible for relaxing the arteries, so these medications stop the arteries narrowing and help produce longer, more satisfying erections.

One of the most common causes of ED is a problem with reduced blood flow: arterial insufficiency or an arterial blockage. Poor arterial flow can stem from diabetes,³ high cholesterol,⁴ or smoking.⁵

4. Hormonal imbalances

Sometimes, hormonal imbalances are to blame for ED. Low levels of testosterone are associated with erectile dysfunction, as testosterone plays an important role in libido. Abnormal thyroid hormone levels can also cause ED.^6,7  

The numan take

Broadly speaking, erectile dysfunction is often caused by a malfunction in four main categories: psychological issues, nerve signalling, blood flow, and hormonal imbalances.

The surest way to get to the bottom of what might be causing your ED is with a Sexual Performance Test Kit: a simple, at-home blood test that can identify if you have any underlying health conditions that could be contributing to your ED.

References

^{1 Yafi FA, Jenkins L, Albersen M, Corona G, Isidori AM, Goldfarb S, et al. Erectile dysfunction. Nat Rev Dis Primers. 2016;2:16003.}

^{2 Shiri R, Koskimäki J, Tammela TLJ, Häkkinen J, Auvinen A, Hakama M. Bidirectional relationship between depression and erectile dysfunction. J Urol. 2007;177(2):669–673.}

^{3 Kouidrat Y, et al. High prevalence of erectile dysfunction in diabetes: a systematic review and meta-analysis of 145 studies. Diabet Med. 2017;34(9):1185–1192.}

^{4 Luo D, Sun D, Colonnello E, Pan LP, Wu S, Guo J, et al. Mechanisms of dyslipidaemia-induced erectile dysfunction: a narrative review. Front Endocrinol (Lausanne). 2026;17:1780243.}

^{5 Cao S, Yin X, Wang Y, Zhou H, Song F, Lu Z. Smoking and risk of erectile dysfunction: systematic review of observational studies with meta-analysis. PLoS One. 2013;8(4):e60443.}

^{6 Mikhail N. Does testosterone have a role in erectile function? Am J Med. 2006;119(4):373–382.}

^{7 Liu X, Wang Y, Ma L, Wang D, Peng Z, Mao Z. High prevalence of erectile dysfunction in men with hyperthyroidism: a meta-analysis. BMC Endocr Disord. 2024;24(1):58.}