The bureaucrats at the FDA, bless their pointed little heads, claimed in a Consumer Advisory Bulletin back in 2009 that colloidal silver “may” interfere with the absorption of prescription drugs like penicillamine, quinolone, tetracycline as well as thyroxine medications.

This claim has stuck, being repeated incessantly across the internet by well-known websites such as WebMD.com, MayoClinic.com, RxList.com, the National Institutes of Health website and numerous others.

But is the claim true? And can the FDA document it? Turns out, they can’t. Here’s the story…

Back in October I wrote to you about my adventures in trying to get the FDA to document their claim that colloidal silver “may” interfere with the absorption of certain prescription drugs.


No evidence for the idea that colloidal silver can interfere with the absorption of prescription drugs and medications – google image 

  • You might remember that I pointed out the claim has been repeated ad nauseum all over the internet, and is being used by certain well-known colloidal silver detractors to frighten people away from trying colloidal silver.
  • I also explained that I’d hired a researcher from the pharmaceutical industry to comb through the online PubMed database records to see if he could find any clinical studies that backed up the FDA claim. He found none.
  • I then conducted my own research, and could find no corroborating evidence for the idea that colloidal silver can interfere with the absorption of prescription drugs and medications.
  • Finally, I emailed the FDA, and politely asked them to document their claim, stating:
  • “I’ve read with interest your Consumer Advisory at this link and found the following comment I’d like clarification on:
  • ‘In addition, the use of silver-containing dietary supplements may interfere with the body’s absorption of some drugs, such as quinolone antibiotics [ciprofloxacin (Cipro), norfloxacin (Noroxin), ofloxacin], tetracycline antibiotics, thyroxine, and penacillamine (Cuprimine).’
  • Could you please respond with the documentation for this statement?
  • I’ve searched the PubMed database and cannot at this point find any clinical studies documenting the details in this statement. I’d very much appreciate it if you could send me the documentation.

But the FDA responded with a terse, one-line sentence that read as follows:

“You can file a freedom of information request for any information we have related to this issue by following guidance located on our web site at http://www.fda.gov/RegulatoryInformation/FOI/default.htm“

In other words, they told me to go pound sand.


My FOI Request

  • Obviously, if I wanted the information, I was going to have to work for it. I assume the bureaucrats figured I wouldn’t go through the trouble of filing an official Freedom of Information Act (FOIA) request.
  • Boy, were they wrong. I filed a Freedom of Information Act request on 10/10/2012. And four days later I received the following email from them:
  • The Food and Drug Administration (FDA) has received your Freedom of Information Act (FOIA) request for records regarding:
  • We will respond as soon as possible and may charge you a fee for processing your request. If your informational needs change, and you no longer need the requested records, please contact us to cancel your request, as charges may be incurred once processing of your request has begun.
  • For more information on processing fees, please see http://www.fda.gov/RegulatoryInformation/FOI/FOIAFees/default.htm.
  • If you have any questions about your request, please call Thelma B. Ghahhari, Information Technician at (301) 796-8980 or write to us at:
  • Division of Freedom of Information, U.S. Food and Drug Administration
  • 12420 Parklawn Drive, Room 1050,
  • Rockville, MD 20857
  • Fax:(301)827-9267
  • Ah…now we’re getting somewhere, I thought. At least they’re acknowledging my FOIA request. And they even appeared to understand my question. Progress!
  • But then October ended and November rolled around. And December. And finally, I figured I wasn’t going to hear from them at all.

No Proof, No Credibility

  • Until December 6th, when I received a plain white envelope in the mail from the Department of Health & Human Services, the FDA’s parent organization.
  • Opening the envelope, I found a one-page letter, which, boiled down to the essentials, stated:
  • “Dear Mr. Barwick:
  • In response to your request of October 15, 2012 for information pertaining to dietary supplements containing silver.
  • We have searched our files and find no responsive information.”
  • There you have it.
  • The FDA admits they have no documentation for their claim that colloidal silver “may interfere with the body’s absorption of some drugs, such as quinolone antibiotics [ciprofloxacin (Cipro), norfloxacin (Noroxin), ofloxacin], tetracycline antibiotics, thyroxine
  • , and penacillamine (Cuprimine).”
  • To add insult to injury, the letter ended by stating “The following charges for this request to date may be included in a monthly invoice: $23.00”
  • Yep. The FDA is going to charge me $23 to tell me they have no documentation for their own claims.
  • What a great country, huh? I can only wonder what the charge would have been had they actually found evidence for their own claims!
  • You’d think they’d be too embarrassed to charge money for having to admit they’ve just been making stuff up out of thin air. But no. Bureaucrats have no shame.

Colloidal Silver Myths


Colloidal Nano Silver 7ppm

Of course, this kind of thing should come as no surprise, especially in regards to colloidal silver.

After all, there are numerous myths being perpetrated about colloidal silver, as I’ve described in my previous article, 8 Prevalent Myths and Misconceptions About Colloidal Silver.

I guess I can add one more myth to the pile, which is to say, the myth that when the government makes a claim about colloidal silver, they actually have documentation to back up their claim.

In All Fairness

  • Of course, I’m not a doctor. I’m a natural health journalist. So if you’re concerned about this topic, do be sure to run this article by your doctor and get his advice.
  • After all, I’d be remiss if I failed to point out that just because the FDA has no documentation for their claim, doesn’t mean the claim isn’t true.
  • In spite of the profound lack of evidence, there nevertheless might well be people who have trouble processing certain prescription medications. And maybe colloidal silver usage could make it worse, in some rare cases.
  • As we’ve seen, at present there’s apparently ZERO clinical evidence for this. But that doesn’t mean it can never happen.
  • After all, it wasn’t too long back that doctors figured out that eating grapefruit before taking certain medications could in some rare instances prevent the body from properly excreting those medications, and therefore cause those medications to build up to unhealthy levels in a small subset of people.
  • So if you choose to use colloidal silver, and you take prescription medications of any kind, you’re still responsible for working with your doctor to make sure your medication is working correctly, and your supplementation with colloidal silver (or any other nutritional supplement, for that matter) is not interfering with it.
  • This of course can easily be done through simple blood tests that would determine if blood levels of the drug are too high or too low, or if the desired effect of the drug is taking place, i.e., for example, tests to determine whether or not your thyroid medication is keeping your thyroid hormone at the proper levels.
  • Obviously, if your doctor is concerned about your colloidal silver usage due to certain medications you’re taking, you can talk to your doctor about mitigating the possibility of interaction between your colloidal silver supplement and the absorption of your medications by taking the colloidal silver at least several hours after taking the medications, or even at opposite ends of the day.
  • That way, as I mentioned in my previous article on this topic, your medications are already fully absorbed by the body before colloidal silver is introduced into the body.
  • Yours for the safe, sane and responsible use of colloidal silver,


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