I've heard the story that crocodile dung was used as a contraceptive aid, but I admit I have a hard time believing it - wouldn't the smell alone prevent copulation from occurring? Do we know of any contraceptives, effective or not, used in ancient Egypt? What about abortifacients?
I realize "ancient Egypt" is pretty broad. If you're able to narrow down, I'm interested in the late Bronze Age/early Iron Age, but I'd accept answers from any period.
The use of crocodile dung as an abortifacient can probably be traced to the Kahun Gynecological Papyrus. It is mentioned immediately after an entry entitled "Remedy for Getting Pregnant" (a fertility treatment). The entry containing crocodile dung is called "To prevent..." and I will reproduce it in its entirety here:
... crocodile's dung cut up (?) on auyt-paste 1, sprinkled .............
(translation from Griffith, F. Ll. The Petrie Papyri: Hieratic Papyri from Kahun and Gurob, accessible here).
Another translation reads that the crocodile dung should be "chopped over HsA and awyt-liquid" (Stephen Quirke).
So, crocodile dung appears to be used in some sort of medical procedure to prevent something, according to an ancient Egyptian text about "women's problems".
The use of crocodile feces and "fermented dough" (an alternate translation of "auyt-paste") as a contraceptive in vaginal suppository form appears also on the Ramesseum Medical Papyrus IV (which I am unable to find a translation of, but all sources indicate that the recipe is the same as in the Kahun papyrus).
So it appears that they did in fact use crocodile feces as a contraceptive. I'm actually as astounded as you are.
Now, it's worth noting that this is certainly not the only contraceptive that ancient Egyptians used. There are other remedies from the Ebers Medical Papyrus that use acacia fruit, colocynth, dates, and honey, and make a vaginal suppository out of that (Ebers 783).
And vaginal suppositories, though they appear to be the oldest method (dating at least from 1800 BC in the Kahun Gynecological Papyrus) certainly weren't the only method. Around 1300 BC, according to the Berlin Medical Papyrus, one was supposed to use a combination of fumigation of the vagina with emmer seeds and an oral treatment composed of oil, celery, and sweet beer.
For further reading and details, I highly encourage you to look at