Can you sweat out a hangover?
Short Answer: Yes and No.
The YES.
Since my college days I have always worked out to help ease my hangover and it has yet to fail me. However, I would also drink a crapload of Gatorade (or electrolyte-filled fluid of your choice) and I made sure to eat something prior to my workouts. If you are THAT hungover that you can't even stomach the thought of eating or drinking water then please go back to sleep and do not waste your time working out.
So how does your body actually "sweat out" a hangover? According to Dr. Aaron White (Senior Scientific Advisor to the Director at the National Institute on Alcohol Abuse),
The vast majority of alcohol—95 to 98 percent—is metabolized by the liver. But the remaining two to five percent is excreted unchanged in sweat, urine, feces, breath, saliva and breast milk - Dr. Aaron White
So, basically if there’s any alcohol still in our body when we wake up the next day then YES a little bit of this will be excreted via sweat. However, it's clearly minimal and not enough to "cure" your hangover.
The NO.
Hangovers happen because of all the alcohol that has already been metabolized by the liver that unfortunately you can't sweat out. It literally "hangs" around causing those throbbing headaches and upset stomachs. The damage has already been done and you can't sweat that alcohol out.
So why workout then?
Based on my own experience, I have learned that working out amidst a hungover state does more than just help me "sweat it out". Exercising releases all those lovely ENDORPHINS, which are what make us feel so great, thus combating the hangover funk. Exercising post night of drinking can also do the following...
Help with that post night out anxiety
Give you the energy boost you've been craving all day
Distract the mind
Help with the guilt you maybe experience (for being a lazy piece of crap earlier in the day)
Urge you to drink more H20 throughout the day (so important)
As long as you are not on your death bed after a long night out, you have enough water and food in your stomach AND you are being mindful of the intensity of your workout then you should be good to go.
All in all, a 100% cure to a hangover is to not get one in the first place. Know your body and try not to overdo it the night before. Easier said than done right? Well, not really. To be honest, I can't hang like I used to pre-child. I can't drink even close to the amount of alcohol I consumed before I had Claire. I've learned to drink slowly, drink water throughout the night and of course eat a good meal. Anything is better than waking up with one eye open and praying it's only 3am and not 3pm. Yikes, we've all been there.