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Is My Semen Too Thick? Sperm Viscosity, Explained

If you’re trying to conceive, you’re probably thinking way more about your sperm and semen than you ever have, and viscosity is one thing to look into. If you’re starting to worry whether your semen is too thick – don’t panic. In most cases, thick semen isn’t a huge issue for male fertility.

However, if it’s consistently really thick and sticky, it could be a sign of high sperm viscosity – which can impact the way your sperm cells move and their chance of reaching the egg.

In this blog, we’ll break down everything you need to know about sperm viscosity and how you can improve it.


What is sperm viscosity?

The word ‘viscosity’ means a measure of a fluid’s resistance to deformation – or in non-scientific language, it’s a way of measuring how thick the liquid is. For example, maple syrup would have a high viscosity rating, custard would have a medium viscosity rating and water would have a low viscosity rating.

When it comes to a semen analysis there are generally two parameters used to assess the ‘thickness’ of semen.

First, the clinicians would look at liquefaction – or how long it takes for the semen to become more fluid after ejaculation. Under normal conditions, a healthy system will liquefy fairly rapidly thanks to enzymes breaking down the gel-like structure of the semen. This usually happens within 20 minutes (if you have done one of our at-home tests, you’ll have seen this for yourself!). Delayed liquefaction could indicate a problem with the prostate or the seminal vesicles.

They will then look at sperm viscosity. Viscosity is measured by drawing the sample into a pipette and allowing the semen to drop – pulled simply by gravity – and the thread it leaves is measured. A healthy semen sample will have a tiny thread. According to WHO specifications, semen that leaves a thread more than 2 cm long is classed as having ‘abnormal viscosity’.


How does tick semen impact fertility?

Semen with abnormally high viscosity makes it harder for your sperm cells to swim. If we think back to the earlier example, if you were trying to swim through treacle, you would find that much harder than swimming through water!

If your sperm find it harder to swim, it’s likely that you are struggling with low motility – a common reason behind male factor infertility. Low motility makes it harder for your sperm cells to reach the egg in time to fertilize it/before they die.

There are also studies linking semen with high viscosity (or hyper-viscous semen) to other issues surrounding male fertility. One study found that semen with high viscosity is more likely to have an elevated number of white blood cells, which can impact sperm health. Another study noted that hyperviscous semen could be a result of an inflammatory condition or infection of the genital tract, which would also make it more prone to other poor sperm health parameters including low motility and increased DNA fragmentation.


How can I improve sperm viscosity?

If you are looking to improve your sperm viscosity and make it healthier – there are a few things you can do. The good news is they are largely the same things we would advise for improving any factor of your sperm health!

  1. Stay hydrated – this is a huge one for sperm viscosity! If you don’t have enough fluids in your body then it’s tough for your body to produce nice, fluid semen! Try to drink at least 3 liters a day and avoid diuretics like alcohol (as they will make you dehydrated)
  2. Avoid inflammatory foods – If there is a connection between inflammation and sperm viscosity, then eating an anti-inflammatory diet could potentially help.
  3. Bad habits like smoking and alcohol can all have an impact on your sperm health – including its consistency – so try to avoid them.
  4. Avoid things that could cause heat damage in your testicles – including saunas, hot tubs, and using your laptop directly onto your lap.


Getting to know your semen – and your swimmers – is important for understanding your health and your fertility. With our at-home male fertility test, it’s never been easier.

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