Peptides shipped from outside the US pass through customs, where CBP can refer them to FDA, and FDA can detain, refuse or destroy products that appear to be unapproved drugs. Peptides shipped from inside the US to a US address don't cross a border, so customs isn't part of the process. That's the main reason ship-from location is one of the things we check for every vendor.
Notice: Research peptides are sold for in-vitro laboratory research only. They are not FDA-approved, not for human or animal consumption, and this page is not medical advice.
This page explains the public process. It isn't legal advice, and it doesn't cover, and won't help with, getting products past inspection. If you receive a notice, read it carefully and consider talking to a lawyer.
Domestic vs international: the basic difference
| US domestic shipment | International shipment | |
|---|---|---|
| Crosses a border | No | Yes |
| Screened by CBP | No | Yes |
| Can be referred to FDA at entry | No | Yes |
| Common notices | Carrier delivery issues only | Notice of FDA Action, CBP seizure notice |
| Typical transit | Days | Weeks (Swiss Chems quotes 2-3 weeks for international standard) |
A domestic shipment isn't "approved" or "cleared" by anyone. It simply never goes through import screening. FDA's position on research peptides, covered in FDA peptide regulation 2026, applies to sellers wherever they ship from.
How international parcels are screened
FDA explains the mail route on its International Mail Facilities page. Mail from abroad arrives at a USPS International Mail Facility. There are eight, in Florida, Hawaii, Illinois, New Jersey, New York, California, Puerto Rico and the US Virgin Islands. CBP examines packages and refers FDA-regulated products to FDA investigators, who check whether they comply. FDA says it looks at "human drugs" including unapproved and counterfeit products.
The import alerts that apply
FDA import alerts tell its field staff which products may be detained without physical examination (DWPE). Three are relevant to peptides:
- Import Alert 66-41: "Detention Without Physical Examination of Unapproved New Drugs Promoted In The U.S." Products from firms on its Red List can be detained without examination. It says personal importation shipments follow FDA's Regulatory Procedures Manual Chapter 9-2, while commercial or promotional shipments are "generally not amenable to the use of enforcement discretion." FDA's import alert list showed a publish date of September 25, 2026.
- Import Alert 66-80: GLP-1 receptor agonist bulk drug substances. FDA launched this "green list" alert on September 5, 2025. GLP-1 active ingredients from sources not on the green list face detention. The alert says that of 48 GLP-1 API sites FDA evaluated, 21% were noncompliant. Its page showed a revision dated September 21, 2026.
- Import Alert 66-78: drugs detained based on analytical test results. Not peptide-specific, but it covers drugs FDA has tested and found contaminated, substandard or substituted.
What a Notice of FDA Action means
When FDA detains an imported product, it sends a Notice of FDA Action. On mail shipments, FDA says the notice will be marked "Detained" or "Detained/[May be Destroyed]" (FDA).
The notice explains why the product appears subject to refusal and gives the recipient an opportunity to respond, according to FDA's page on its administrative destruction authority. From there:
- If the response shows the product complies, FDA releases it.
- If not, FDA refuses admission. The product may be returned or destroyed.
- Destruction: since 2016 (for drugs, under FDASIA section 708), FDA can destroy a refused drug valued at $2,500 or less, after giving notice and a chance to present testimony.
Detention is an FDA import decision about the product. It's a different process from a CBP seizure.
What a CBP seizure notice means
A seizure is a customs action under CBP's own authority. CBP's guide for the trade community, What Every Member of the Trade Community Should Know About Seizures, says that after a seizure CBP issues a Notice of Seizure to interested parties. The recipient can, among other options:
- do nothing, in which case CBP begins forfeiture by public notice,
- ask CBP to speed up forfeiture,
- file a petition for relief,
- make a settlement offer, or
- file a claim and cost bond to move the case to court.
The standard petition window is 30 days, which CBP can extend. The notice itself lists the deadlines that apply. Because forfeiture is a legal process, this is the point to speak with a lawyer rather than rely on forum advice.
Enforcement at the border: a recent example
On April 1, 2026, WHIO reported that CBP officers in Cincinnati had intercepted about 5,000 individual shipments of unapproved peptides from China, found across more than 300 master cartons. Each carton held about 15 unmanifested parcels with prelabeled US addresses. The report lists retatrutide, semaglutide, tirzepatide, MOTS-C, semax and cagrilintide among the products. CBP's own release is titled "Cincinnati CBP foils scheme to smuggle over 5,000 unapproved peptides into the U.S." Cincinnati Port Director Eric Zizelman said, "Noncertified or unlicensed chemicals from other countries present serious health risks."
The parcels were stopped at the port, before they reached the individual US addresses on their labels. For more 2026 events, see our regulatory news tracker.
Why US-only vendors matter
For a buyer evaluating a vendor, a US ship-from location and a US-only shipping policy remove one source of risk: the parcel isn't subject to import screening, and there's no customs notice to deal with. It also usually means shorter transit, which matters for storage.
It doesn't make a vendor compliant or its products legal for human use. And a vendor that "ships from the US" may still import its raw material; the Cincinnati case involved parcels shipped from China under US labels. That's why we pair ship-from location with testing and documentation checks.
Where our eight vendors ship from and to
Checked against each vendor's policy pages; see each review for sources. Listed in our editors' ranking order, which isn't sorted by score (method).
| Vendor | Ships from | Ships to |
|---|---|---|
| American Peptides | Shreveport, LA | US, plus international (per its policy) |
| NextGenPeps | California | US, Puerto Rico and US territories only |
| PSPeptides | New Jersey | US, Canada, EU, UK, Australia |
| Ascension Peptides | US (address not published) | US only |
| Peptide Plugs | Liberty Hill, TX | US only |
| Swiss Chems | Not stated (says US-based) | US and international |
| Licensed Peptides | Not stated (Boca Raton, FL address published) | US only |
| Alpha Pro Peptides | US (address not published) | US only |
For shipping speed comparisons, see fastest shipping peptide vendors. For the overall list, see best peptide vendors in the USA.
Before you order
- Check the ship-from location in the vendor's shipping policy, not just "US-based" marketing.
- Check the vendor's FDA record in the warning letter database. Our 2025-2026 shutdown timeline lists recent actions.
- Check the lot's COA before it ships, using our COA guide.
- Read the lost-package policy. Some vendors, such as Ascension Peptides, make lost packages the buyer's responsibility unless shipping protection was bought.
Shipping rules sit on top of state law, covered in peptide laws by state.
Updated September 26, 2026. This is a summary of public FDA and CBP materials, not legal advice.