Why the "Seafood" Scent Occurs

The primary reason for a fishy or seafood-like scent is the breakdown of substances called polyamines (such as putrescine and cadaverine). When these compounds are released and interact with the slightly acidic environment of the vagina, they can produce an odor that is commonly described as "fishy."

Several factors contribute to this:

Bacterial Balance: The vagina hosts a complex microbiome, dominated by Lactobacillus bacteria. When there is an imbalance—often called Bacterial Vaginosis (BV)—the "good" bacteria decrease and "bad" anaerobic bacteria thrive. These anaerobic bacteria produce the amines mentioned above, which creates a distinct, pungent, seafood-like odor.

pH Levels: The vaginal environment is naturally acidic, which helps prevent infections. When the pH rises (becomes less acidic), it can create a more favorable environment for the odor-producing bacteria to grow.

Sweat and External Factors: Apocrine sweat glands (located in the groin area) produce a type of sweat that is rich in proteins and fats. When bacteria on the skin break down this sweat, it can produce a stronger scent.

Diet: Just as diet affects body odor elsewhere, certain foods—particularly those high in sulfur or strong-smelling spices—can influence the scent of bodily fluids.

When to Seek Advice

While a mild, characteristic scent is normal, a strong, fishy odor that is persistent or accompanied by other symptoms is often a sign of an underlying issue:

Bacterial Vaginosis (BV): This is the most common cause of a strong fishy odor. It is usually treated with antibiotics.

Infections: Trichomoniasis (a common STI) is also frequently associated with a strong, fishy-smelling discharge.

Other Symptoms: If you notice itching, burning, pain, or a change in the color or consistency of discharge, it is important to consult a healthcare provider for an accurate diagnosis and treatment.

Most vaginal odors are a result of normal biological processes, but a sudden or intense change usually indicates that the balance of the vaginal microbiome has been disrupted.

(http://www.autoadmit.com/thread.php?thread_id=5879070&forum_id=2,5#49974496)

The distinction matters:

In living mammalian cells, putrescine is mainly produced by the enzyme ornithine decarboxylase, which decarboxylates ornithine. Putrescine is then used to synthesize higher polyamines such as spermidine and spermine. These molecules support cell growth, DNA/RNA stabilization, translation, and tissue repair. Cadaverine is less central in normal mammalian metabolism and is more associated with microbial activity.

After tissue damage, infection, gut microbial activity, or death, bacteria produce large amounts of putrescine and cadaverine by decarboxylating amino acids:

Putrescine comes mainly from ornithine or indirectly from arginine.

Cadaverine comes mainly from lysine.

So the main cause, especially when people refer to “release” of putrescine and cadaverine as odor-associated compounds, is bacterial breakdown of proteins and amino acids, particularly during putrefaction. That is why these compounds are strongly associated with decay, necrotic tissue, infection, fecal material, and decomposing bodies.

Operationally:

Protein breakdown → free amino acids → bacterial decarboxylation → polyamines.

The biochemical cause is decarboxylation; the ecological/physiological driver is usually microbial decomposition or dysbiosis-associated metabolism.

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so basically the same thing that causes PUTREFACTION in CADAVERS?

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Yes — for putrescine and cadaverine specifically, largely yes.

They are classic products of putrefaction, especially after death, when bacteria break down proteins and decarboxylate amino acids:

lysine → cadaverine

ornithine → putrescine

That is why their names are so evocative: cadaverine is associated with cadavers, and putrescine with putrefaction.

The caveat is that putrescine is also a normal mammalian metabolite in living cells. Mammals make it enzymatically for growth, repair, and polyamine synthesis. So the presence of putrescine alone does not necessarily mean decay.

But when you see putrescine plus cadaverine, especially with foul odor, tissue breakdown, necrosis, infection, fecal contamination, or postmortem change, then yes: the same basic process is involved — microbial decomposition of amino-acid-rich tissue.

So the clean version is:

In cadavers: bacterial putrefaction is the dominant source.

In living mammals: normal cells make some polyamines, but large odor-associated releases usually point to bacterial decomposition, infection, necrosis, or gut microbial metabolism.

(http://www.autoadmit.com/thread.php?thread_id=5879070&forum_id=2,5#49974698)

Because the odor is mostly from volatile amines — small nitrogen-containing molecules that can smell “fishy,” “rotting,” or “chemical” depending on concentration and context.

In vaginal dysbiosis or bacterial vaginosis, anaerobic bacteria break down amino acids and other nitrogen-rich compounds. That can produce amines such as:

trimethylamine — strongly fishy; also responsible for the smell of old fish

putrescine — decaying/meaty odor

cadaverine — decaying/foul odor

tyramine and other biogenic amines — can add sharp, sour, or rancid notes

The reason it smells more “fishy” rather than just “rotten” is that trimethylamine is especially fish-like. Fish odor is chemically associated with trimethylamine because marine fish contain trimethylamine oxide, which bacteria reduce to trimethylamine as fish spoils. In the vagina, different bacteria can generate amines through their own metabolism, and when the pH rises, those amines become more volatile and easier to smell.

So the simplified chain is:

BV-like dysbiosis → more anaerobic bacterial metabolism → more amines → higher pH makes amines evaporate more → fishy odor

That last part is important. Amines are weak bases. In an acidic Lactobacillus-dominant vagina, more of the amines are protonated, meaning they are less volatile and less smelly. When pH rises, more amines shift into their free-base form, which evaporates more readily and reaches the nose.

That is also why the smell may become stronger after sex or around menstruation: semen and blood are more alkaline than the normal vaginal environment, so they can raise pH and liberate more free amines.

So no, the “fish” smell does not mean there is fish involved, and it does not mean the vagina is decomposing. It usually means the local microbial chemistry has shifted toward amine-producing bacteria plus higher pH.

(http://www.autoadmit.com/thread.php?thread_id=5879070&forum_id=2,5#49974709)