A change could mean something is going on, or it could just mean you had asparagus for dinner.
Good health is all about maintaining your body's natural state, or homeostasis (to give it it's fancy term).
You've got to know what's normal for you and if that changes, you'll know something's up. If your pooing habits suddenly change, that can be a cause of concern or at least, investigation. And the same is true about your pee.
Generally speaking, our pee tends to smell the same. But if that changes, then it's worth knowing why that might be - and when to visit your GP about it.
It's believed that asparagus, in particular, contains asparagusic acid which our bodies break down into sulfur compounds.
Some of us can smell it, some of us can't. We don't yet know if that's because some people just can't smell it or they don't actually produce the smell.
We know that when we don't drink enough, our pee becomes darker in colour and as it becomes more concentrated, its smell also becomes more pungent.
For that reason, your urine probably smells strongest first thing in the morning, when you've gone eight hours without having a glass of water.
And they can make our pee smell disgusting. Not that you'll be paying much attention, what with all the stinging sensations.
"Occasionally, an abnormal connection between the bowel and bladder called a fistula can make the urine smell bad as well as cause recurrent urine infections," Dr Laniado explained.
It's very rare but again, if your urine smells really bad and you've crossed out all of the above, it's GP time.
Dr Marc Laniado, a urologist at Doctify, told Women's Health: "Some drugs in the sulpha class, which are also known as sulphonamides, can make the urine smell bad. Sulphonamides have been used for the treatment of infections and epilepsy."
If you also find that you're constantly thirsty, you've got headaches and you need to pee a lot, make an appointment with your GP.
Blood: Blood is the most serious sign. If you're not on your period, then blood in urine can be a sign of cancer and you need to get checked out ASAP.
Frequency: Sure, drinking a couple of litres a day is going to see you going to the loo quite frequently, but you should know what's normal for you. If you find yourself dashing to the loo a lot more regularly than normal - despite not drinking loads, it could be a sign that you've got a sugar control issue.
This article first appeared in The Sun and has been republished here with permission.