“I washed just like I always do—why is there this smell?” When an unfamiliar, unpleasant odor suddenly appears on your underwear one day, many people feel flustered or anxious, wondering, “Am I the only one like this?” In the clinic, it’s quite common to see patients who have spent several days searching alone and worrying over this single symptom. To get straight to the point: a smell that differs from usual is not something to be ashamed of—it can be a common health signal that the bacterial balance inside the vagina is shifting. In this article, we’ll walk step by step through what to check and how to respond from the moment you first notice that smell.
Why the smell sends the first signal
Bacterial vaginosis is often first noticed through smell. In a healthy vagina, the beneficial bacteria lactobacilli predominate and keep the environment acidic, and this acidic environment prevents the overgrowth of other microbes. When this balance is disrupted, anaerobic bacteria increase and produce substances with a characteristic fishy odor. The U.S. Centers for Disease Control and Prevention (CDC) describes bacterial vaginosis as a state of “bacterial imbalance in the vagina,” in which beneficial bacteria decrease and anaerobic bacteria increase excessively (CDC, 2021).
So it’s more accurate to view the smell not as a simple hygiene problem but as a signal that the balance has been shaken. In the clinic, many patients say, “I washed more often, but it actually got worse,” and this is because excessive washing also rinses away the beneficial bacteria that serve as a protective barrier. In other words, the effort to get rid of the smell can paradoxically make the cause worse.
What kind of smell and discharge raises suspicion
When a smell that differs from usual appears, the first thing to consider is bacterial vaginosis. However, the smell and discharge have a few characteristic patterns, and knowing these can help reduce vague anxiety and gauge when to seek care.
- A fishy, fish-like smell, especially more noticeable around your period or after intercourse
- Thin, gray or white discharge that has increased compared to usual
- Mild itching or stinging, or a foreign-body sensation at the vaginal opening
Conversely, bacterial vaginosis can also pass with almost no symptoms. CDC data also reports that a considerable number of cases are found without clear symptoms (CDC, 2021). So rather than brushing it off with “there are no symptoms other than the smell, so it’s probably fine,” if a change from usual continues for several days, it’s safer to have it checked. If you’re curious about the criteria for distinguishing normal-range discharge from infection, you may also refer to an article to read when you’re unsure whether your vaginal discharge is normal.
The moment you notice the smell, what you can do at home
The most important principle at the moment you first notice the smell is “don’t touch it” rather than “strip it away.” Many people, in their haste, use more cleansers or try to wash inside the vagina, but the initial response is better the simpler it is.
If you wash the inside of the vagina vigorously just because there was a smell, the beneficial bacteria that would restore the balance get rinsed away too, and symptoms can last longer. In the early stage, gently rinsing the vulva with lukewarm water is enough.
The lifestyle habits helpful in the early stage can be summarized as follows. Pause vaginal cleansers for a while or greatly reduce how often you use them, and switch your underwear to breathable cotton to keep it from staying damp. Around your period, pay attention to cleanliness but avoid excessive washing, and take care of your sleep and stress management. However, such lifestyle adjustments are only supportive measures, and if the smell and discharge changes persist for more than a few days, confirmation through a consultation is needed rather than self-judgment. If you hesitate in the early stage of symptoms, you may also consult about your symptoms first via chat.
Vaginitis types that look similar but are different
It’s difficult to distinguish bacterial vaginosis from other types of vaginitis based on the symptoms of smell and itching alone. The biggest reason self-treatment is not recommended lies precisely in this “looking similar.” The table below simplifies and organizes three types that are commonly confused in the clinic.
| Type | Typical pattern | Smell | Common misconception |
|---|---|---|---|
| Bacterial vaginosis | Thin gray/white discharge | Fishy fish smell | Blaming oneself for poor hygiene |
| Candida vaginitis | Thick white discharge, itching | Smell tends to be mild | Assuming all increases in discharge are fungal |
| Trichomonas | Frothy discharge | Unpleasant smell | Mistaking it for simple vaginitis |
The three types have different causative organisms and responses, so using the same medication does not improve all of them. There are quite a few cases of patients who use over-the-counter candida products on their own and come in because there was no improvement. In cases related to a sexually transmitted infection like trichomonas, the approach is again different, so an article organizing the transmission routes and causes of trichomonas vaginitis is also worth referring to. In the end, accurate differentiation starts with confirmation in the clinic.
How it’s confirmed in the clinic
Bacterial vaginosis is confirmed using relatively standardized methods. In obstetrics and gynecology, history-taking and examination are the basics, and when necessary, a discharge test is added for a comprehensive assessment. The internationally widely used criteria (Amsel criteria) look together at the pattern of vaginal discharge, whether the vaginal pH is higher than normal, the characteristic cells seen under the microscope (clue cells), and whether the fishy smell intensifies when an alkaline solution is added to the discharge (CDC, 2021).
The reason for looking at multiple items together is that a single clue alone can be confused with other types of vaginitis. In particular, when symptoms recur or the pattern differs from usual, a screening test to differentiate sexually transmitted infections may also be performed. Since an accurate diagnosis is what allows you to avoid unnecessary treatment and head in the right direction, rather than buying medication right away just because there was a smell, we first recommend confirmation through a consultation. If you have recurring vaginitis, you can also review the direction of diagnosis and management in the women’s disease treatment guide.
Treatment and recurrence: what’s good to know
Bacterial vaginosis improves with antibiotic treatment in most cases. Oral or vaginal-suppository antibiotics are typical, and they are usually taken or used for a set period. The U.S. CDC and the American College of Obstetricians and Gynecologists (ACOG) recommend the metronidazole or clindamycin classes as standard treatment (CDC, 2021; ACOG). However, which formulation to use and for how long varies depending on the individual’s condition, so it’s best to decide through a consultation.
One thing worth knowing in advance is that recurrence is not uncommon. Cases of experiencing symptoms again within a few months after treatment are reported (CDC, 2021), and so lifestyle correction is as important as treatment. In the past, partner treatment was generally said to be unnecessary, but recently evidence has been presented that partner treatment may help in recurring cases, so depending on the situation it’s good to discuss with the medical staff (ACOG). If you’re curious about the direction for reducing recurring vaginitis, we recommend reading on with lifestyle management to prevent vaginitis and how to live well with chronic vaginitis.
It’s a symptom you don’t need to feel ashamed of
A smell on your underwear that differs from usual is a common thing that can happen to anyone. It often arises not because you neglected hygiene, but rather because everyday changes such as excessive cleansing, hormonal changes, or a drop in immunity shake the balance. Once you understand the cause, responding becomes much simpler. Not ignoring the signal of the smell and checking it in time—that is the heart of the initial response.
Rather than repeating searches alone and feeling anxious, if a change from usual continues for several days, please check your symptoms now through a chat consultation with a light heart. In the clinic, we identify the cause by type and guide you all the way to the direction of reducing recurrence.
Written by: Lee Dong-hee, Director · Obstetrics and Gynecology Specialist · View medical staff profile
First published July 8, 2025 · Last reviewed May 30, 2026
References: CDC STI Treatment Guidelines (2021), ACOG (American College of Obstetricians and Gynecologists)
This article is intended to provide general health information and does not replace individual diagnosis or treatment. If you have symptoms, please consult through a medical visit.