Quick note before we get into it: I'm sharing what I'm personally comfortable with based on my conversations with my doctors. Talk to yours about what's right for you. Cool? Cool.
The Main Question - Booze
Here's the headline: "pump and dump" is old school. We used to think your boobs like… stored the booze. They don't. Breast milk mimics your blood alcohol content. So if you're not drunk, your milk isn't drunk.
My general rule of thumb was if I felt physically and neurologically normal — like, not tipsy, could SAFELY drive, I just had a single light drink — it's fine to feed.
That said — if you ARE actually tipsy, or you're just not comfortable feeding after a drink and your boobs are full or you need to maintain supply, you can absolutely pump. Just don't feed it. When I do this I toss the milk, but some people save it for milk baths, which they swear is amazing for baby skin. Seems like a nice middle ground if dumping perfectly good breast milk makes you want to cry. (It might. Hormones are wild.)
If you're being super conservative: wait 1–2 hours after one drink before feeding. Longer for more drinks. But again — it tracks your BAC, not some separate boob-alcohol reservoir. Once you feel normal, you're good.
Also also — we have a breathalyzer in our house. Because we have every gadget ever invented and sold to members of the public in our house. If you're not sure where you're at, blow. Takes the guesswork out of it entirely. But honestly, if you feel like you should blow, you're probably safer just skipping the feed and pulling a bag out of your freezer stash.
Related but Unrelated - Other Meds
"Pump and dump" also comes up in relation to medications. This one I'd genuinely work with your doctor on. Seriously — don't Google it. Your doctor or pharmacist can check any specific medication for you. Some pass into milk, some don't. Some are stored in tissue longer than others. It's not one-size-fits-all.
That said, lots of antibiotics are fine to feed through. Baby does get some of them though, so some folks give baby probiotics while mom is on antibiotics, since in theory the good bacteria is also getting nuked. We like Culturelle for this.
One resource I love: the InfantRisk HCP app. It's great for quick "is this safe while breastfeeding?" checks, both for meds during pregnancy and while nursing. Doesn't replace your doctor, but it's a solid gut-check tool when you're standing in the pharmacy aisle at 9pm with a killer sinus infection with sudden anxieties about Afrin, Sudafed, and antibiotics.
Part of our All Things Breastfeeding & Pumping guide.