Giardia is a parasite, a life form that lives off its host.  They include worms, bacteria and in the case of giardia a single cell protozoa, which attaches itself to the wall of the intestine, where it destroys the lining. Right, enough of the science stuff, lets look at how you can get it and what the symptoms are.


Giardia can be passed from person to person during sexual activity, so it is classed as a sexually transmitted infection (STI). However, it’s also caught through eating or drinking contaminated food or drink; (it is common in what are classed as developing countries).

The parasite can live outside the body for several days too! The easiest ways of catching giardia during sex is through rimming, sharing sex toys, fingering, fisting and unprotected anal sex. It is passed on through poo coming into contact with the mouth, so try to be aware of where your fingers have been.


Half of all infected people have no symptoms at all, but if they do appear, the symptoms can be:

  • Dehydration
  • Diarrhoea
  • Nausea
  • Fever
  • Cramps
  • Flatulence

There can also be very severe symptoms which include; weight loss, chronic diarrhoea and the inability to absorb food. It takes between one and three weeks for the inflammation giardia causes to produce symptoms.

If you are HIV positive and take medicines that cause diarrhoea, a parasitic infection such as giardia may go undetected. People with immuno-deficiency related conditions are very much at risk.


In order to test for Giardia, a sample of your poo is taken.  This is then looked at to find signs of the parasite.


Giardia is usually treated with a short course of antibiotics. As with all antibiotics it is very important that you finish the course of tablets even though the symptoms may have subsided. It’s also important for your sexual partners to get checked too, as they are likely to be infected (even if they are not showing any symptoms). If you’re a bit embarrassed about doing this or are finding it difficult to get in touch with your partners, the clinic where you get tested can help. They can contact people on your behalf and let them know without giving your name.

How to avoid it

Using condoms with lots of water-based lubricant for anal sex, gloves for fisting and fingering and dental dams for rimming, can help prevent the infection from being passed on. Also, remember to wash thoroughly (especially under your fingernails) after any sex involving arse play.