Debunking Semen Myths

Nov 03, 2010 • Lessons

pearl necklace

You’ve met the man of your dreams (or, at least, tonight’s dreams). You decide to practice the age-old tradition of going down — and we’re not talking about a trip to Venice… that’s just unthinkable. Everything’s going great, he’s ready to explode, and then — @#$%! Who just lit my eyes on fire?!

That’s right, a shot of man goo in the eye, and you’d swear you’d been pepper sprayed at point-blank range. There’s been much debate on the interwebs as to why taking it in the eye stings worse than the thought of a Palin and O’Donnell presidency. Here’s a rundown of the myths relating to semen from a bonafide scientist type doctor-person who’s way too educated for his own good. No, bonafide is not a euphemism.


Any connoisseur of the creme will tell you the first thing they notice about the taste of semen is its saltiness. So it makes sense people would think the high salt level in semen would burn. Let’s try an experiment. Grab a handful of Morton’s finest and rub it in your eyes… or not (really, don’t). For those who did, I’ll let you go blindly fumbling around the kitchen screaming while you rinse out. Back? Good. See? Salty hurts.

So salty semen’s gotta hurt. Unfortunately, semen is about the same saltiness (called osmolality) as the rest of your body — mostly (1). Sperm are cells and have similar salt level requirements that are pretty much like all the other cells in your body. If they were swimming around in a Dead Sea salt-bath, they’d die. Next time you bite your lip, pay attention to the blood. Salty, right? How about when that cute minx (AV?) shoots down your best pickup line and you’re crying in your beer? Salty tears? The same saltiness as semen.

So that salt level shouldn’t hurt.

Science nerd warning: semen is really a teeny bit saltier, but not enough to sting like the dickens. Compared to blood serum, we see 336.1 ± 20.2 vs. 291.1 ± 6.9 mOsm/L, respectively (3).


A woman’s va-jay-jay (to quote the late, great Oprah, or is she still around?) is a little bit alkaline. We’re not talking pickle your trouser-snake lyme pH here, but very slightly basic. That gives rise to the belief that semen is acidic to counter the difference and make everything happy and pleasant like a mountain spring (so thirsty now).

As much as male bravado would have you think it, no… our jizz can’t etch glass. Actually, semen itself is about neutral pH. One of the main ingredients in semen is bicarb. So you’re basically shooting Alka-Seltzer at her. That’ll mess with your head next time you reach for the hangover cure (2).

Now look at the ingredients in eye drops. They’re buffered neutral — just like semen. So the acidity myth is out.

Sperm releasing acid

There is a common misconception (ha!) that sperm are packing acid to help them dissolve the outer layer of the egg, thus gaining entry. Actually, the sperm use enzymes. A woman’s egg is covered in several layers of defenses that protect the egg from harm as it bounces its way merrily through the Fallopian tube. When the sperm finally meet the egg, they need some way to dig through those defenses.

Now remember that the sperm are basically swimming around in Alka-Seltzer. If they released a small payload of acid to dissolve the egg’s defenses, the buffer they are in would immediately neutralize the acid. That’s like throwing a pebble at a mountain; it’s not gonna move it.

In reality, inside the sperm sits a package of enzymes. They’re housed in a complex bag called an acrosome (the Coach line of acrosome bags should be out in Spring 2011). When this bag opens, the enzymes go to work drilling through the egg’s layers to allow the sperm to finally plow through the egg (4). I tried to propose the reverse cowgirl theory for easier egg plowing, but nobody listened to me.

So sperm acid packets are out.

Sperm “impregnating” eye

The sperm get just one shot to use their precious, small, payload of enzymes to get into the egg, so they are very precise when they use them. If they didn’t have precise control over when to use them, they might misfire and lose their chance. It’s this precise control that prevents the sperm from using their enzymes on your eye and drilling into it. Also, the enzymes are very specific as to what they drill into. They need the right-shaped target to have any effect.

Even if the swimmers did take a crack at your lady’s eye, the enzymes wouldn’t fit: think square peg and round hole. So it’s just another bit of protein floating around uselessly.

Gah…all this talk of control, misfires, plowing, pegs, holes…is it getting hot in here?


1. J Assist Reprod Genet. 2010 Feb;27(2-3):83-6. Epub 2009 Dec 12.
2. Int J Urol. 2010 Oct;17(10):839-47. doi: 10.1111/j.1442-2042.2010.02619.x.
3. DOI: 10.1046/j.1365-2605.2002.00353.x
4. PLoS Biol 2005 Sep 6;3(10):e323

Part 2: The Ingredients in Semen
Part 3: The Different Kinds of Sperm