Most people are aware of the, by now heavily scientifically-supported, fact that alcoholism and chronic alcohol abuse take a serious toll on the immune system — leaving addicts vulnerable to infectious diseases.  Yet, whether you've got a flu, a common cold, or a sore throat, some folks will be quick to suggest you add booze to your list of home remedies, right alongside honey, vitamin C tablets, and chicken soup.
What effect does your alcohol consumption have on your risk of catching a cold or flu?
The "moderate" (up to one drink per day for women, and two for men) consumption of alcoholic drinks rich in polyphenol — like wine and beer — may actually, research suggests, have a positive impact on the functioning of your immune system . One study specifically examined what effect downing three or four alcoholic beverages a day (quite a lot by most standards!) has on a person's susceptibility to the common cold. The research team found, perhaps surprisingly, that people who drink this much don't get as many colds as others — but only if they're not also smokers.  The same does not hold true for the flu, however .
Yes, alcohol acts as an analgesic
Alcohol dulls your senses, of course — and that means, a meta-analysis of studies into the effect alcohol has on pain, that it can also act as quite an effective pain reliever. Not only does downing three or four standard drinks increase your pain tolerance, it also dulls pre-existing pain. This finding explains why people with chronic pain are more likely to abuse alcohol as well as why it used to be offered to pregnant women in labor, but it also goes some way toward supporting the folk tale that alcohol can reduce cold and flu symptoms, including sore throats. 
No, you still shouldn't be using it to treat your flu or cold
If you're home with a cold, flu, or unspecified and undiagnosed "bug", chances are that you'll also be using over-the-counter painkillers — and they don't go well with alcohol, at all. Acetominophen (Tylenol, paracetamol) isn't so great for your liver on its own, but adding booze to the mix can actually place you at risk of acute liver failure. Combine aspirin with booze, meanwhile, and you risk gastric bleeding. 
Vomiting and diarrhea are both commonplace in people with the flu, and both place you at risk of becoming dehydrated as you lose fluids more quickly than you're able to add them to your system. Drinking any significant amount of alcohol only adds to your odds of dehydration. If you're currently fighting off a cold, you won't be throwing up or struggling with bouts of diarrhea, but you will suffer from nasal congestion — again something that alcohol can only make worse, as dehydration will make that mucus denser. 
- Research shows that hot liquids — which can be anything from hot toddies to chicken soup — help loosen the nasal mucus that makes the common cold so annoying. The reason is pretty simple; as you ingest a hot liquid, its vapor will rise up into your nasal cavity. Hot liquids function as a kind of mini steam inhalation therapy, in other words. 
- Some studies indicate that taking large doses of vitamin C helps cure the common cold faster . Vitamin C likewise has some germ-fighting action, though it would be more accurate to say that not getting enough increases your risk of becoming ill than to say that boosting your intake fights illness .
- Honey, which has potent antibacterial properties, has been shown to be helpful in treating coughs , the common cold , and influenza .
Finally, for those who know that alcohol is commonly used as a disinfectant and who therefore believe that drinking it will probably help kill whatever germs or viruses are currently plaguing them, we have bad news there, too. A dental study suggested that an ethanol concentration of at least 40 percent is required for alcohol to have any significant antimicrobial effect — so booze likely won't help you out in that department, either. 
While the moderate consumption of some kinds of alcohol does appear to have a protective effect against the common cold, and despite the fact that alcohol indeed offers effective short-term pain relief, we wouldn't recommend that you hit the booze while you're ill. It won't help you overcome the bug you're fighting any faster, and drinking larger amounts can put you at serious risk of dehydration. If you want to try old folk remedies to overcome your illness faster, stick to hot liquids, honey, and lemon.