Coloidal silver is another one of those health fads which while it is based in a minor part of reality, is in fact a scam and a fraud. You see, while colloidal silver might indeed have certain antibiotic effects, it aslo has some rather bad side effects. And not only that, we now have vastly better antibiotics which you should be better off using rather than the colloidal silver. Here’s an example of the sort of claims made for colloidal silver:

In the world of colloids, particle surface area is the property of colloidal silver that directly determines the ability of the colloid to react with its environment. Therefore the effectiveness of colloidal silver is predicated on particle surface area. The higher the particle surface area the more effective the colloidal silver.
Particle surface area is defined as the total surface area in square centimeters (cm2) of all the particles in one milliliter (mL) of colloid. In the world of chemistry the ability of one substance to interact with other substances in its environment is predicated on the surface area of the substances or stated another way, reactivity increases with increasing surface area. A larger value of particle surface area increases the reactivity of the colloid.
In the booklet "Silver Colloids" Professor Gibbs wrote "The size of the particles in the colloidal silver suspensions we use for health purposes is very important. Particle size controls the surface area and therefore the effectiveness of the colloidal silver suspension."
For this reason particle surface area is the single most important property of colloidal silver. It is not uncommon for non-technical readers to mistaken believe that the concentration (ppm) of silver is the most important property. Companies selling silver protein type products will advertise very high values of silver concentration with the explanation that higher ppm concentrations are more effective but that is simply not true. In fact silver protein products have very low values of particle surface area owing to the very large size particles present in those products. For a complete discussion on silver protein products read The Truth About Silver Protein Products.

That’s the sort of mumbo jumbo claptrap that gives science a bad name. OK, the effectiveness of colloidal solutions is dependent upon particle size: fine, we can agree with that. But what they haven’t shown in any manner is that colloidal suspensions of silver do you any good at all. Or try this:

The first natural antibacterial product approved for patent by the United States Patent Office since about 1924.
Clinically PROVEN to kill 536 strains of bacteria!
We do not claim that Silvagen™ will cure any disease. What we are stating is that Silvagen™ has been proven to kill the bacteria that is associated with the following ailments: Pneumonia, Food Poisoning, Eye Infections, Skin Infections, Boils, Cellulitis, Post-operative infections, Toxic Shock Syndrome, Meningitis, Osteomyelitis, Sinusitis, Otitis Media (ear infections), Impetigo, Scarlet Fever, Strep Throat, Urinary Tract Infections, Wound Infections, Endocarditis, Dental Plaque and Tooth Decay, Burn Infections, Keratitis, Nosocomial Infections, Enteric Fever, Respiratory Tract Infections, Diarrhea, Throat & Sinus Infections, Epiglottis in Children, Suppurative Arthritis in Children, and more.

There’s  few problems with those claims: for example, cellulitis is not a bacterial infection. Nor is osteomyelitis. If it is effective against epiglottis in children (something we are most dubious about) why isn’t it in adults? These are the sort of claims we associate with snake oil salesmen I’m afraid, not with proper medicine.

It’s also worth noting that penicillin  has been shown to be more effective in those diseases where bacteria are indeed resent: which is why the medical world uses it and its derivtives rather than silver.

Oh, and you know that silver is a heavy metal? So drinking a solution of it is giving yourself heavy metal poisoning? And if you want the full skinny on colloidal silver you can always read Quackwatch:

Colloidal silver is a suspension of submicroscopic metallic
silver particles in a colloidal base. Long-term use of silver
preparations can lead to argyria, a condition in which silver
salts deposit in the skin, eyes, and internal organs, and the
skin turns ashen-gray. Many cases of argyria occurred during the
pre-antibiotic era when silver was a common ingredient in nosedrops.
When the cause became apparent, doctors stopped recommending their
use, and reputable manufacturers stopped producing them. The official
drug guidebooks (United States Pharmacopeia and National Formulary)
have not listed colloidal silver products since 1975.

Or you can see the video of the man turns blue if you prefer.