Customers in the United States can receive products shipped from Mexico, but medicines are not treated in exactly the same way as ordinary international purchases. Once a medication reaches the U.S. border, American import rules become part of the process, and those rules are separate from the pharmacy work that took place before the parcel left Mexico.
Medication Imports to the U.S.
A medicine can be lawfully sold through the Mexican pharmaceutical market and still have a different regulatory position when it is offered for entry into the United States. FDA generally considers foreign versions of drugs that have not been approved for the U.S. market to be unapproved drugs under U.S. law, even when the medicine is registered and normally sold in another country. This is why Mexican authorization, pharmacy dispensing and U.S. import admissibility need to be looked at as separate things. The pharmacy can prepare a legitimate Mexican-market product for shipment, but the decision about whether that product may enter the United States belongs to the U.S. authorities applying U.S. law.
Personal Importation Is Not a General Permission
This is probably the most important point for anyone ordering medicine from outside the United States. FDA does have a personal importation policy, but it is not a blanket rule saying that every person may freely import a certain amount of foreign medication. The agency describes personal importation as a situation where a product is being brought in for the individual’s own use and not for resale or further distribution, and FDA personnel may use enforcement discretion in limited circumstances.
In other words, the policy gives FDA room to consider the facts of an individual shipment. It does not give the customer an automatic right to import any medicine simply because the order is personal.
When FDA May Consider a Personal Medication Shipment
For prescription products used for a serious condition, FDA identifies several circumstances that may support a personal importation decision. These points are considered together, not as separate guarantees:
- The medicine is being used for a serious condition for which effective treatment may not be available in the United States through commercial or clinical means.
- The product is not being commercially promoted to people living in the United States.
- The medicine does not appear to create an unreasonable health risk.
- The customer confirms in writing that the product is for personal use.
- The quantity is generally no more than a three-month supply.
- The customer provides the name and address of the U.S.-licensed doctor responsible for the treatment, or evidence that the medicine is being continued after treatment began in another country.
What the “90-Day Rule” Actually Means
The phrase “90-day rule” is used so often online that it can sound like a legal allowance by itself, but that is not how FDA describes the policy. A quantity of approximately three months is only one part of the personal importation criteria, and staying below that amount does not automatically make a foreign medicine admissible.
A 30-day or 90-day shipment can still be refused if the product does not meet the other conditions or raises a separate regulatory issue. This distinction is important for U.S. customers because quantity alone should never be treated as permission from FDA.
CBP, FDA and DEA
Several U.S. agencies can become involved with the same shipment, depending on what is inside. Their responsibilities are different:
| Agency | What It Does |
|---|---|
| U.S. Customs and Border Protection (CBP) | Handles entry into the United States, customs procedures, declarations, duties and the initial examination of imported merchandise. |
| Food and Drug Administration (FDA) | Reviews FDA-regulated products such as prescription and over-the-counter medicines and decides whether they meet the requirements for admission. |
| Drug Enforcement Administration (DEA) | Applies additional federal rules when a medicine is a controlled substance under the Controlled Substances Act. |
Duty Rules for Low-Value Packages
For many years, U.S. customers became accustomed to the $800 de minimis threshold and sometimes assumed that a parcel below that value could simply enter without much customs involvement. That changed. Duty-free de minimis treatment for most low-value shipments from all countries was suspended beginning August 29, 2025, including international mail, and CBP continued that suspension through its 2026 rules.
For customers receiving medicines from Mexico, the important part is not simply whether a particular shipment ultimately has customs charges. The larger change is that a parcel being inexpensive no longer places it outside the normal import system just because its value is below $800. CBP can require entry information, applicable duties or fees can depend on the product and its classification, and FDA requirements continue to apply independently of the parcel’s value.
U.S. Postal Entry Rules Changed Again in 2026
U.S. Customs and Border Protection introduced another important change on June 24, 2026, creating a new procedure for low-value merchandise entering the United States through the international postal network, and after a relatively short implementation period this new postal informal entry process began requiring considerably more shipment information than customers and carriers were used to under the older de minimis system. The change is especially important for international pharmacy shipments because even when the customer places an ordinary online order, the package itself may now move through a customs process that depends on much more detailed information about what is inside, where it came from, how much it is worth, and how it entered the country.
For postal shipments that qualify for this procedure, the information submitted to CBP may include the product description, country of origin, tariff classification, declared value, applicable duty rate, carrier details, tracking number, arrival port, and the date the shipment reaches the United States. Most of this work is handled by the carrier, broker, or another party responsible for filing the customs entry, so the customer is not expected to turn a pharmacy checkout into a customs declaration form, but accurate information about the medication and its actual value becomes much more important once the parcel enters this system.
The declared value also needs to reflect the real value used for customs purposes, because describing a medication shipment as a gift, assigning an artificially low amount, or giving the product a description that has nothing to do with what is actually inside may create additional problems instead of making entry easier. International pharmacy shipments are still subject to the same basic requirement that the information accompanying the parcel should accurately describe the goods being sent.
U.S. Import Changes for Mailed Shipments
One part of the June 2026 CBP rule did not take effect immediately, because shipments that are also subject to the requirements of another federal agency were given a longer transition period before full compliance became necessary. In customs systems these agencies are commonly referred to as Partner Government Agencies, or PGAs, and because prescription medicines fall under FDA jurisdiction, this transition is directly relevant to mailed drug shipments whenever FDA-related entry information is required as part of the import process.
That transition period is scheduled to end on October 22, 2026, and after this date some shipments covered by these provisions may need to move through the formal entry process unless an eligible filer uses CBP’s new Entry Type 13 test, which creates an electronic informal-entry option for qualifying international mail shipments valued at $2,500 or less. This change does not mean that a customer ordering a single box of medicine suddenly becomes responsible for personally completing federal customs paperwork, because depending on the shipment the entry can still be handled by a carrier, customs broker, purchaser, or another qualified filer, but it does mean that considerably more import processing may now take place behind what still looks to the customer like an ordinary low-value international pharmacy parcel.
What Formal Entry Can Mean
Formal entry is more involved than the traditional low-value postal process, and although CBP generally uses it for shipments valued above $2,500, the same procedure can also be required for lower-value merchandise when another federal agency has jurisdiction over the product or when CBP determines that a more complete entry is necessary. For medication shipments this distinction matters because the purchase price alone does not decide how a parcel will be processed once it reaches the United States.
A formal entry can involve a customs filing, additional product information, and in some cases a customs bond, which is why importers frequently use a licensed customs broker when this level of processing is required. If CBP determines that a mailed shipment must enter through this procedure, the recipient may be notified that the parcel has arrived and given instructions explaining what has to be completed before the shipment can continue, so even a relatively inexpensive medication order can sometimes require more documentation than its value might initially suggest.
Medicines With Additional Import Rules
Controlled substances belong to a separate category and should not be treated in the same way as an ordinary non-controlled prescription medication when discussing import rules. FDA specifically explains that the Drug Enforcement Administration generally determines whether a controlled substance can be imported for personal use, and when both agencies have jurisdiction over the same product, FDA and DEA may coordinate their review.
A prescription that is valid in another country does not automatically override U.S. controlled-substance restrictions, which means that products in this category can be subject to considerably tighter requirements even when they were legally prescribed and purchased abroad. For customers ordering medicines internationally, this is an important distinction because the general FDA principles commonly discussed in connection with personal importation should not be assumed to apply to controlled substances in exactly the same way.
If FDA Stops a Medication Shipment
An FDA hold is very different from an ordinary shipping delay, because in this situation the question is no longer simply when the package will arrive, but whether the medication itself is admissible under U.S. law. When FDA believes that an imported drug appears to violate applicable requirements, the agency can issue a Notice of FDA Action explaining why the shipment has been detained or may be refused and giving the recipient an opportunity to provide additional information before a final decision is made.
The customer can respond through the FDA contact identified in the notice and submit information intended to address the reason for detention, after which FDA decides whether the product can be released into the United States or should be refused. For certain refused drugs arriving through international mail or express courier with a value of $2,500 or less, FDA also has administrative authority to destroy the product instead of allowing it to proceed through the import process. For this reason, an official FDA notice should never be treated in the same way as a routine carrier tracking update, because it concerns the legal admissibility of the medicine itself and may require the recipient to take action within the procedure and timeframe described in the notice.