I've heard that once a person catches a cold, his whole immune system becomes weak and is affected. In what way does having a cold influence the immune system?

If it does weaken it, how can one keep the immune system strong while the person is infected with a cold?

  • There is a whole lot thing going on with cold, if you want to get into technical details, as someone mentioned, you can see it here
    – azam
    Commented Jun 1, 2015 at 13:25

2 Answers 2


I've written on this subject a few times, but the most relevant question ended up being closed, and the other is on Bio.SE, so I will mostly focus on tailoring the information there to the specifics of this question.

If you look at ether of my previous answers, you will note the first thing we need to establish is what is causing the common cold. From the body of evidence coming from the US and China I believe the answer to that is HRV followed by RSV.

Your immune system is actually directly attacked by two of the proteins RSV makes when it infects cells (NS1 and NS2). This knowledge is actually linked to a pretty cool vaccine idea for RSV. Thus I think it quite appropriate to think that active RSV infections weaken your immune system.

Looking at the very good epidemiology data coming from China (here's another example in addition to the first), it seems that the rate of co-infection, that is something else besides these two viruses infecting the patient, is quite high, particularity with RSV. This would imply that other pathogens take advantaged of a "weakened" immune system in an RSV infection.

It's less clear with HRV, but that might just be because of how amazingly common HRV infections are. It seems as though HRV induces a good immune response, in healthy patients, but it was still commonly found with other pathogens present (though not in rates as high as RSV). There is not a clear mechanism for HRV if it is in fact weakening the immune system (which actually might be better described as a "distracted" immune system in this case).

As for what you can do? Not a whole lot once symptoms show up. Contrary to whatever ads you may see, even some poor un-blinded trials, taking vitamin C is not going to help after you already have the cold. Even the prophylactic benefit seems to only be in certain cases, and I want to strongly discourage megadosing vitamin C, which in most cases does nothing helpful (and can cause problems of it's own).

Staying hydrated is always a good option, as is washing your hands and coughing/sneezing into your elbow to prevent infecting others. Other than that, you can hope for any of the vaccine candidates currently be researched to actually work, or that one of the small molecule inhibitors (anti-viral drugs) to actually be safe.


When you get infected your immune system gets damaged a little because it is already being engaged in fighting the existing disease. Its priority will be to fight the disease completely but not maintain a good level.

So, a little extra amount of work is required to increase the optimum immunity level in your body. That is why people say, you need to be safe from falling prone to attract new diseases when already infected (like don't have cool drinks etc).

Keeping immunity levels to the peak always is the best advice and it has to be done constantly not only being conscious when you're affected.

Apart from only having foods which have positive effects on immunity e.g. essential Vitamins like C, A, D etc. our daily lifestyle also matters a lot.

Anyways to answer your specific question, "what to do when you're ill?", WebMD has drafted a good article and check list which has to be made sure we follow always. "6 Immune System Busters & Boosters"

To summarize,

1. You're short on sleep.
2. You don't exercise.
3. Your diet is off.
4. You're always stressed.
5. You're too isolated.
6. You've lost your sense of humor.

Cutting down each one of the culprits should help. Please follow the link for more details.

  • can somebody explain why this answer is bad?
    – Ooker
    Commented May 23, 2015 at 14:12
  • @Ooker Cytokine responses, TH1vs TH2 imbalanced responses, depending on which virus is at fault (the break down on Wiki is probably still wrong on viral %, see my Bio.SE on similar subject), the virus itself could be interfering with your immune system (e.g. NS1/NS2 proteins in flu or RSV). Quite simply this misses a lot of the physiological responses and pathogenesis and deals with only with life style issues.
    – Atl LED
    Commented Jun 1, 2015 at 2:15
  • @AtlLED if so, can you make a better answer?
    – Ooker
    Commented Jun 1, 2015 at 5:29
  • @Ooker I decided that Th1 vs Th2 responses was too much into the "weeds" of immunology, but I actually already drafted a paragraph to include the discussion. You can let me know if you think it should make it into my answer.
    – Atl LED
    Commented Mar 7, 2016 at 4:11

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