Source: https://www.fda.gov/ICECI/EnforcementActions/WarningLetters/2013/ucm348369.htm
Timestamp: 2019-04-22 10:23:12+00:00

Document:
This is to advise you that the Food and Drug Administration (FDA) has reviewed your web site at the Internet address http://birkmeds.com in January 2013 and has determined that your products Immune Response 247, Cholestat, Silymarin 81, and LevelStat are promoted for conditions that cause the products to be drugs under section 201(g)(1)(B) of the Federal Food, Drug, and Cosmetic Act (the Act), [21 U.S.C. § 321(g)(1)(B)]. The therapeutic claims on your website establish that the products are drugs because they are intended for use in the cure, mitigation, treatment or prevention of disease. The marketing of these products with these claims violates the Act. You can find the Act and implementing regulations through links on FDA's Internet home page: http://www.fda.gov.
“Studies have shown that medicinal mushrooms [an ingredient in your product] contain … properties that … offer help … individuals with cancer, asthma, and other chronic illnesses."
Your products are not generally recognized as safe and effective for the above referenced uses and, therefore, the products are new drugs as defined in section 201(p) of the Act [21 U.S.C. § 321(p)]. New drugs may not be legally marketed in the United States without prior approval from FDA as described in section 505(a) of the Act [21 U.S.C. § 355(a)]. FDA approves a new drug on the basis of scientific data submitted by a drug sponsor to demonstrate that the drug is safe and effective. The introduction of unapproved new drugs into interstate commerce is a violation of section 301(d) of the Act [21 U.S.C. § 331(d)].
Furthermore, your products are misbranded within the meaning of section 502(f))(1) of the Act [21 U.S.C. § 352(f)(1)] in that they are offered for conditions that are not amenable to self-diagnosis and treatment by individuals who are not medical practitioners; therefore, adequate directions for use cannot be written so that a layperson can use these drugs safely for their intended purposes. The introduction of misbranded drugs into interstate commerce is a violation of section 301(a) of the Act [21 U.S.C. § 331(a)].

References: § 321
 § 321
 § 355
 § 331
 § 352
 § 331