Online pharmacy
Since about the year 2000, hundreds of pharmacies have begun operating over the internet. Many such pharmacies are, in some ways, similar to community pharmacies; the primary difference is the method by which the medications are requested and received. Some customers consider this to be more convenient than traveling to a community drugstore.
While most internet pharmacies sell prescription drugs only with a prescription, some do not require a pre-written prescription. Some customers order drugs from such pharmacies to avoid the inconvenience of visiting a doctor or to obtain medications which their doctors were unwilling to prescribe. These websites employ their own in house physicians to review the situation and write a prescription accordingly.  Some websites have been known in the past to offer medications without a prescription or a doctor review.  However, this practice has been criticized as potentially dangerous, especially by those who feel that only doctors can reliably assess contraindications, risk/benefit ratios, and an individual's overall suitability for use of a medication. There have also been reports of such pharmacies dispensing substandard products.  Pharmacies offering medication without a prescription and doctor review or supervision are sometimes fraudulent.
In the United States, there has been a push to legalize importation of medications from Canada and other countries, in order to reduce consumer costs. Although importation of prescription medication currently violates Food and Drug Administration (FDA) regulations and federal laws, enforcement is generally targeted at international drug suppliers, rather than consumers.  Often Americans purchase lower-cost foreign drugs by driving to Canadian or Mexican pharmacies, buying their medications when traveling abroad on vacation, or, buying from foreign pharmacies that ship their orders via mail.

# Overseas online pharmacies and U.S. law
Legality and risks of purchasing drugs online depend on the specific kind of drug being purchased, as well as its amount.
- It is illegal to purchase controlled substances from an overseas pharmacy. Generally speaking, a person purchasing a controlled substance from such a pharmacy may be violating two federal laws which can carry stiff penalties. The act of importation of the drug from overseas violates 21 USC, Section 952 (up to 5 years in prison and $250,000 fine for importation of non-narcotic Schedule III, IV, or V drugs; possibly more for narcotics and Schedule I and II drugs). The act of simple possession of a controlled substance without a valid prescription violates 21 USC, Section 844 (up to 1 year in prison and $1,000 fine). Note that FDA does not recognize "online prescriptions"; in order for the prescription to be valid, there has to be a face-to-face relationship between the patient and the health care professional prescribing the drug. Sections 956 and 1301 provide exemptions for travellers who bring small quantities of controlled substances in or out of the country in person, but these exemptions do not cover delivery via a mail carrier.
- The act of importation of any prescription drug (not necessarily a controlled substance) violates 21 USC, Section 301(aa), unless the following conditions are met (as listed in Section 804):
The drug is imported from Canada, from a seller registered with the Secretary (i.e. with FDA);
The drug is imported from a licensed pharmacy for personal use by an individual, not for resale, in quantities that do not exceed a 90-day supply;
The drug is accompanied by a copy of a valid prescription;
The drug is a prescription drug approved by the Secretary;
The drug is in the form of a final finished dosage that was manufactured in an establishment registered under section 510; and
The drug is imported under such other conditions as the Secretary determines to be necessary to ensure public safety.
- The drug is imported from Canada, from a seller registered with the Secretary (i.e. with FDA);
- The drug is imported from a licensed pharmacy for personal use by an individual, not for resale, in quantities that do not exceed a 90-day supply;
- The drug is accompanied by a copy of a valid prescription;
- The drug is a prescription drug approved by the Secretary;
- The drug is in the form of a final finished dosage that was manufactured in an establishment registered under section 510; and
- The drug is imported under such other conditions as the Secretary determines to be necessary to ensure public safety.
- The law further specifies that enforcement should be focused on cases in which the importation by an individual poses a significant threat to public health, and discretion should be exercised to permit individuals to make such importations in circumstances in which the prescription drug or device imported does not appear to present an unreasonable risk to the individual.
- According to Department of Homeland Security Appropriations Act, Section 535, Customs and Border Patrol are not allowed to prevent people from importing FDA-approved prescription drugs. Although originally the law was worded to cover all prescription drugs, countries of origin, and methods of delivery, its final edition specifies that it only applies to importation from Canada, and to "...individuals transporting on their person a personal-use quantity of the prescription drug, not to exceed a 90-day supply". Controlled substances are also explicitly excluded. Therefore, it does not disallow Customs to screen and intercept drugs sent by mail.
- It is also technically illegal to import "non-approved" drugs (21 USC sections 331(d) and 355(a)); however, FDA policies suggest that, under certain circumstances, the patients may be allowed to keep these drugs.
- Individual U.S. states may implement their own laws regulating importation, possession, and trafficking in prescription drugs and/or controlled substances.

## Enforcement
Laws listed in the previous section are not always enforced (or otherwise all online pharmacies would quickly run out of customers and go bankrupt). Among other reasons, strict drug law enforcement is politically unpopular because many customers of online pharmacies are seniors who can't afford to buy their prescription drugs in the United States.
- Any package containing prescription drugs may, in principle, be seized by customs. The package may be held until the addressee provides proof that he is allowed to receive these drugs (e.g. a valid prescription), and eventually returned to the sender if the addressee does not respond. (Sample package detention notification letter) In practice, the number of packages containing prescription drugs sent to United States on a daily basis far exceeds customs' capabilities to inspect them. In the past, packages often passed through customs even if they weren't sent from Canada or otherwise didn't meet the requirements of section 804 of 21 USC. Until recently, about 5 percent of prescription drug packages sent from Canada were being seized.
- At the present time, U.S. customs do not seize packages from Canada.
- DEA and FDA generally do not target consumers unless drugs are imported in large quantities (suggesting intent to distribute) or represent a perceived danger to public health (opiates, amphetamines).
- Rarely, drug importation laws are enforced on the local level. For example, in June 2005 in Baton Rouge, Louisiana, a number of customers of online pharmacies were arrested by local law enforcement officers and charged with possession of a controlled substance without prescription.