Medically reviewed by
Dr. Carla Montrond Correia ND, CNS
5 min read
Urine may never have an odor that one would describe as pleasant, but if the smell of your pee seems a bit off, there could be a reason why. Many factors can change the scent produced by pee, from your diet to changes in health. However, one common explanation is taking vitamin supplements. Let’s take a closer look at what vitamins can cause smelly urine and why.
Urine is a waste product composed of the byproducts of your body’s metabolic products: toxic waste filtered by the kidneys, most notably urea and water. The process of urination is a crucial function that removes harmful waste from your body.
Your body stores urine inside the bladder which keeps the harmful waste safely away from the bloodstream then releases it through the urination reflex, in other words, when you pee. Urine itself generally looks like a yellow liquid varying from a light, mostly transparent appearance to a dark, nearly opaque amber (especially when you haven’t been drinking enough water).
Urine consists primarily of water, which has no scent of its own. It is the small concentration of waste products that causes urine’s smell. When urine has a high concentration of water and a low level of waste products, then it will have little to no odor.
However, your urine will have a strong odor when it contains a high level of waste products whether it is due to dehydration or other factors. Often when dehydration is at fault, it will be a strong ammonia smell. However, other factors can often be involved as well, including medication and diet, as well as certain medical conditions.
All urine contains ammonia in some concentration, and in some cases, this is strong enough for you to smell. This can be an unpleasant aroma; however, in most cases, it is harmless. It may simply be caused by being a bit dehydrated or consuming certain foods, such as asparagus or foods containing a lot of protein or vitamins.
If your pee has suddenly changed its scent since you started taking a new vitamin supplement, there may be a simple and benign reason for this. Water-soluble vitamins, most commonly vitamin B6, can cause a change in urine odor. Most commonly, these vitamins will produce a characteristic musty pee smell often described as similar to the smell of the vitamins themselves.
This is not harmful, but if it bothers you, this smell will typically go away simply by lowering your intake. Other water-soluble vitamins, including vitamin B1, can cause a smell as well. This smell occurs because your kidneys filter out concentrations of the water-soluble vitamins that your body does not use, and these pass into the bladder where they are released in urine. When you do not drink enough water, the smell will likely increase because your urine will contain a higher concentration of vitamins in proportion to water.
There are several reasons besides vitamins that your pee may smell. First of all, certain foods can result in a change in urine smell and color, most notably asparagus. Researchers have found that this is because your body converts 1,2-dithiolane-4-carboxylic acid within asparagus into sulfur-containing compounds that produce the urine smell. Not everyone experiences this sulfur-y smell, but that’s due more to our individual sense of smell than what is occurring with our urine.
Other foods, such as fish, garlic, Brussels sprouts, and onions, among others, can cause foul-smelling urine. Even certain beverages, such as coffee and alcohol, can cause changes in urine smell.
In addition, certain medications and medical conditions can have a major impact on urine smell. Simply not drinking enough water or holding your bladder for a long period can lead to a stronger urine smell. This can result in a greater concentration of waste and give bacteria a longer time to build up. To solve this, stay hydrated and try not to hold off on urinating for too long.
In some cases, smelly urine can be a warning sign that something may be wrong. Paying attention to certain scents may let you know when to talk to a medical professional. In fact, urine samples have been used for millennia in the school of medicine as a tool to help diagnose certain medical conditions.
First of all, sweet-smelling urine can be a sign that your urine has high glucose, which could point to certain medical conditions. Similarly, if you notice fecal-smelling urine or other urine scents that do not seem to be due to lifestyle changes that go away after a short period, you should discuss them with your doctor.
Most changes in urine smell are temporary and harmless. However, in some cases, it is important to seek medical attention. First of all, you should discuss any signs of an overactive bladder accompanying urine smells, such as frequent or urgent urination, with your doctor.
Other physical signs such as a fever, nausea, and pain or irritation while urinating may also suggest the existence of a more serious issue. Additionally, if you have pain in the lower back or non-menstrual blood in the urine, you should consult a medical professional.
Finally, changes in urination, such as cloudy urine or urine that is continuously foamy, can be a sign of something more serious. It is important to pay attention to changes in urine color as well as persistent changes in scent and discuss them with your doctor.