What does period blood smell like and why?

Menstruation involves the shedding of blood and tissue from the uterine lining through the vagina. It occurs when the egg released during ovulation is not fertilized to result in pregnancy.

The menstrual fluid, consisting of blood, the unfertilized egg, and uterine lining tissue, might have a slight smell to it.

A person might notice that their period blood smells metallic due to the presence of blood and iron.

The vagina’s acidic environment and the presence of different types of healthful bacteria may also play a role in the smell of vaginal secretions and period blood.

Different types of smell
Period blood can have different odors based on numerous factors. The following are common menstrual blood odors:

Metallic
Period blood can have a metallic smell, like a copper coin. This is typically due to the presence of iron in the blood and is not usually a cause for concern. However, it should not persist much longer after the period ends.

Rotten
A person might notice a bad or rotten smell during their period, which could be a sign of a problem. This type of smell is often due to a foreign body, such as a tampon, that a person has accidentally left in the vagina for too long. A person can try to remove an old tampon from the vagina by finding the string and pulling it out. Otherwise, a doctor will need to remove it.

Sweet
A sweet smell in the period blood is likely due to the acidic environment and the presence of bacteria in the vagina.

Body odor
A person might notice a smell that is similar to body odor during their period. This is due to the presence of apocrine sweat glands in the genital region. Apocrine sweat mixes with bacteria on the skin to produce body odor. The glands release this type of sweat during periods of stress or anxiety. It is different from the sweat lost during exercise, or when the body has a high temperature.

Fishy
A person might notice a fishy smell during their period and also outside of menstruation. This smell is often related to an infection, such as bacterial vaginosis or trichomoniasis.

Bacterial vaginosis is a common vaginal infection caused by an overgrowth of bacteria in the vagina. Risk factors for bacterial vaginosis include new or multiple sex partners and douching.

Bacterial vaginosis produces a fishy smell, which is more pronounced during menstruation, as blood increases the vaginal alkalinity. A person might have white or gray vaginal discharge outside of menstruation. Doctors diagnose bacterial vaginosis using a range of tests and typically prescribe antibiotics for treatment.

A person should be aware of new or unusual smells during their period or changes in vaginal discharge outside of their period. Green or yellow vaginal discharge is usually a sign of problems.

Learn more about the different colors of vaginal discharge here.

People should also speak to a doctor if they experience the following during their period:

a fever
severe pelvic or stomach pain
heavier bleeding than normal
A doctor can help to identify whether or not a person has an infection or a more severe condition.