Q: What items are completely banned from USPS international shipping shipping? → A: USPS prohibits shipping ammunition, firearms, fireworks, liquid mercury, and marijuana under all circumstances, with violations carrying felony charges and fines up to $250,000.
For more information, see our complete guide: usps frequently asked questions.
The United States Postal Service enforces strict shipping restrictions to protect postal workers, transportation networks, and recipients from dangerous materials. With over 25,000 hazardous materials incidents reported in 2022 alone—a 150% increase from 2020—understanding these rules has never been more critical for businesses and individual shippers.
Recent changes to USPS regulations in 2026 include updated packaging requirements for hazardous materials, revised postmark definitions effective December 24, 2025, and new international service restrictions. Violating these restrictions can result in package seizure, criminal charges, and fines reaching hundreds of thousands of dollars. Understanding these shipping policies and regulations is essential for compliance.
What Items Are Completely Prohibited in USPS Shipping?
USPS maintains a comprehensive list of items that cannot be shipped under any circumstances due to safety risks and federal regulations. These restrictions apply to all USPS services including Priority Mail, Ground Advantage, and international shipping.
Ammunition and Firearms
Small arms ammunition is classified as an explosive material by the U.S. Department of Transportation and cannot be shipped through USPS. This includes ammunition for pistols, revolvers, rifles, shotguns, primers, blank cartridges, and propellant powder.
Firearm shipping through USPS is extremely limited and heavily regulated under the Gun Control Act of 1968. Only licensed firearms dealers and manufacturers can ship firearms through USPS, and only to other licensed entities.
Mini Q&A:
Q: Can I ship antique ammunition through USPS?
A: No, all ammunition regardless of age is prohibited from USPS shipping.
Q: What about BB gun pellets or airsoft ammunition?
A: These items may be acceptable if they don’t contain explosive charges, but check with your local post office first.
Marijuana and Cannabis Products
Marijuana—whether medical or recreational—is prohibited from USPS shipping and remains federally illegal. Attempting to ship marijuana can result in felony charges under federal law, regardless of state legalization status.
This prohibition extends to CBD products containing THC, cannabis edibles, and any derivative products that fall under controlled substance regulations.
Fireworks and Explosives
All types of fireworks are illegal to ship through USPS due to their explosive nature and fire hazards during air transportation. This includes sparklers, bottle rockets, Roman candles, and firecrackers.
Other explosive materials prohibited include dynamite, TNT, black powder, and improvised explosive devices of any kind.
Which Hazardous Materials Cannot Be Shipped Through USPS?
USPS classifies hazardous materials into nine categories based on Department of Transportation (DOT) guidelines, with many items completely banned from the mail system.
Liquid Mercury and Mercury-Containing Items
Liquid mercury is banned from USPS shipping due to its toxic vapor emissions and environmental hazards. Common household items containing mercury that cannot be shipped include:
- Mercury thermometers
- Mercury barometers
- Mercury switches
- Mercury-containing light bulbs
- Blood pressure monitors with mercury
Even small amounts of liquid mercury can create toxic vapors during transport, posing serious health risks to postal workers and handlers.
Corrosive and Toxic Substances
Strong acids, bases, and toxic chemicals are prohibited from USPS shipping. These include sulfuric acid, hydrochloric acid, sodium hydroxide, arsenic, and most pesticides.
Biomedical waste, including used medical supplies and specimens, cannot be shipped through standard USPS services due to infection risks.
| Hazardous Material Class | Examples | USPS Restriction |
|---|---|---|
| Class 1 (Explosives) | Ammunition, gunpowder, fireworks, airbag inflators | Completely prohibited |
| Class 2 (Gases) | Aerosols, propane tanks, pepper spray | Ground shipping only with restrictions |
| Class 3 (Flammable Liquids) | Gasoline, nail polish, paint thinner | Ground shipping with quantity limits |
| Class 6 (Toxic Substances) | Mercury, arsenic, nicotine, pesticides | Completely prohibited |
| Class 7 (Radioactive Materials) | Medical isotopes, X-ray machines | Special authorization required |
What Common Household Items Have USPS Shipping Restrictions?
Many everyday household items contain materials that require special handling or have quantity restrictions when shipping through USPS.
Lithium Batteries
Lithium batteries power most modern electronics but are considered hazardous materials due to fire and explosion risks. USPS lithium battery restrictions for 2026 include:
- Lithium-ion batteries must be under 300 watt-hours per battery
- Lithium metal batteries are limited to 8 grams of lithium content
- Batteries over 35 kilograms require special DOT approval
- All lithium battery shipments need proper hazardous materials labeling
- Damaged or recalled batteries cannot be shipped
Starting January 27, 2026, USPS requires rigid outer packaging with specific burst strength ratings for all hazardous materials including lithium batteries.
Mini Q&A:
Q: Can I ship a smartphone with its battery installed?
A: Yes, devices with installed lithium batteries under 100 watt-hours can be shipped with proper packaging and labeling.
Q: What about replacement laptop batteries?
A: Replacement batteries must be individually packaged and properly labeled as hazardous materials.
Flammable Liquids and Aerosols
Perfumes, nail polish, hairspray, and cleaning products containing flammable ingredients have strict shipping limitations. These items can only be shipped via USPS Ground services—never by air.
Hand sanitizers must use USPS Retail Ground or Parcel Select services and can only be shipped through local Post Office branches, not online.
Cigarettes and Tobacco Products
Cigarettes and smokeless tobacco can only be mailed in limited circumstances and require approval from a postal employee who verifies the recipient meets legal age requirements. Business-to-business shipments require special permits and compliance with state tax regulations.
How Do USPS Size and Weight Restrictions Affect Your Shipments?
USPS enforces strict size and weight limits across all shipping services to ensure compatibility with processing equipment and transportation methods.
Priority Mail packages cannot exceed 108 inches in combined length and girth, with a maximum weight of 70 pounds. USPS Ground Advantage has a maximum combined girth of 130 inches but charges extra fees for oversized packages. Beyond standard restrictions, shippers should also be aware of potential accessorial charges that can apply to non-compliant packages.
The 2026 rate changes effective January 18 include significant increases: Priority Mail rates rose 6.6% for packages weighing 1 pound or less — see current USPS pricing — while USPS Ground Advantage increased 7.8%. Understanding Priority Mail insurance coverage is also important when shipping valuable items.
Key size restrictions include:
- Letters: Maximum 11.5″ x 6.125″ x 0.25″ thick
- Large envelopes (flats): Maximum 15″ x 12″ x 0.75″ thick
- Packages: Minimum 6″ x 3″ with combined length plus girth under service limits
- Irregular packages require additional postage due to processing difficulties
For shippers looking to reduce costs on compliant packages, ParcelPath offers discounted USPS rates starting 60% below retail pricing with no subscription fees or minimum volume requirements. When calculating package dimensions for pricing, understanding CBM meaning and cubic meter calculations can help optimize your shipping costs for larger items.
What Are the Updated Packaging Requirements for Hazardous Materials?
Effective January 27, 2026, USPS implemented new rigid outer packaging requirements for hazardous materials shipments to improve safety during transport and handling.
Packages weighing 20 pounds or less must have an Edge Crush Test (ECT) rating of at least 32 or burst strength of 200 pounds. Packages over 20 pounds require ECT 44 or 275 pounds burst strength. Proper packaging protection, including appropriate dunnage materials, is essential for securing hazardous materials during transit.
All hazardous materials must include proper DOT-compliant labeling, including:
- UN identification numbers
- Proper shipping names
- Hazard class labels
- Orientation arrows for liquid-containing packages
- “Cargo Aircraft Only” labels when required
Mini Q&A:
Q: Do I need special training to ship hazardous materials?
A: Yes, businesses regularly shipping hazardous materials must provide DOT training to employees handling these shipments.
Q: Can I use any cardboard box for hazardous materials?
A: No, boxes must meet specific strength requirements and be UN-certified for the materials being shipped.
Which Items Can Be Shipped by Ground but Not Air?
Many restricted items are acceptable for ground transportation but prohibited from air transport due to safety concerns at altitude and in pressurized environments.
Ground-Only Shipping Items
USPS Ground Advantage and Parcel Select services accept many items that cannot travel by air, including:
- Perfumes and colognes containing alcohol
- Nail polish and nail polish remover
- Aerosol products under pressure
- Flammable adhesives and solvents
- Safety matches (book matches only)
- Some lithium battery configurations
Ground-only items still require proper packaging, labeling, and quantity restrictions. The average shipping delay for packages containing improperly declared hazardous materials is 2 weeks, according to USPS data from 2022.
Special Handling Items
Cremated remains (human or pet ashes) must be shipped via Priority Mail Express domestically and require special certification. International shipping of cremated remains has additional documentation requirements and may be prohibited to certain destinations.
Prescription medications can only be mailed by Drug Enforcement Administration (DEA) registered distributors to verified recipients. Personal prescription medications cannot be shipped through USPS.
What Are the Legal Penalties for Violating USPS Shipping Restrictions?
The U.S. Postal Inspection Service actively enforces shipping restrictions, with violations carrying severe financial and criminal penalties under federal law.
Criminal Charges and Fines
Attempting to ship prohibited items can result in felony charges with fines up to $250,000 and imprisonment up to 20 years. The Postal Inspection Service reported over 1,200 arrests in 2025 related to prohibited substance shipping.
Specific violations include:
- Shipping marijuana: Felony charges regardless of state legalization status
- Mailing explosives or ammunition: Up to $250,000 fine and 20 years imprisonment
- Shipping vaping products to minors: Up to $10,000 fine and 5 years imprisonment under the PACT Act
- False declaration of package contents: Up to $275,000 in civil penalties
The Preventing Online Sales of E-Cigarettes to Children Act requires age verification and registration with the Alcohol and Tobacco Tax and Trade Bureau (TTB) for businesses shipping tobacco products.
Package Seizure and Investigation
USPS uses advanced X-ray equipment and trained personnel to detect prohibited items. Packages containing restricted materials are seized and may trigger criminal investigations.
Business consequences include loss of commercial mailing privileges, placement on USPS watch lists, and potential civil forfeiture of assets used in violations.
| Violation Type | Maximum Fine | Maximum Prison Term |
|---|---|---|
| Mailing explosives/ammunition | $250,000 | 20 years |
| Shipping marijuana (federal) | $250,000 | 5 years (first offense) |
| Tobacco products to minors | $10,000 | 5 years |
| False HAZMAT declarations | $275,000 | 5 years |
How Can You Verify USPS Shipping Compliance Before Mailing?
USPS provides multiple resources to help shippers verify compliance before sending packages, reducing the risk of violations and delays.
Official USPS Resources
Publication 52: Hazardous, Restricted, and Perishable Mail serves as the definitive guide for shipping restrictions and is updated regularly. The publication is available free at pe.usps.com and includes detailed packaging requirements.
Local Post Office staff can verify specific items and provide guidance on proper packaging and labeling. Many Post Offices now offer 24/7 smart lockers and self-service kiosks for basic shipping needs.
The USPS Business Customer Gateway provides online tools for commercial mailers to verify compliance and access updated shipping requirements.
Pre-Shipping Verification Steps
Before shipping any questionable items:
- Check the current USPS Publication 52 for your specific item
- Verify international shipping restrictions for overseas destinations
- Ensure proper packaging meets strength requirements
- Confirm all required labeling and documentation
- Consider using ParcelPath’s rate comparison tools to find compliant shipping options at discounted rates
Mini Q&A:
Q: Can I ship items that were previously acceptable but are now restricted?
A: No, current regulations apply to all shipments regardless of previous acceptability. Always check current restrictions.
Q: What if I’m unsure about an item’s shipping classification?
A: Contact your local Post Office or USPS customer service before shipping. It’s better to verify than face penalties.
How Do International USPS Shipping Restrictions Differ?
International USPS shipping involves additional layers of restrictions from both U.S. export controls and destination country import regulations. When shipping internationally, understanding the difference between Delivery Duty Unpaid and other customs arrangements is crucial for compliance.
As of January 30, 2026, USPS temporarily suspended international mail acceptance to certain destinations due to inadequate transportation options and service disruptions. Affected countries include several European and Asian destinations.
International restrictions often exceed domestic limitations. Items acceptable for domestic shipping may be prohibited internationally, including:
- Lithium batteries (more restrictive limits)
- Medications and supplements
- Food products and agricultural items
- Electronics and technology products to certain countries
- Cultural artifacts and antiquities
Effective January 1, 2026, USPS eliminated Registered Mail service for some outbound International Services including First-Class Package International Service and Global Express Guaranteed services.
What Are Best Practices for Business USPS Compliance?
Businesses shipping through USPS must implement comprehensive compliance programs to avoid violations and maintain mailing privileges. Understanding the carrier vs shipper relationship helps clarify responsibilities when it comes to compliance and liability.
Employee Training and Documentation
Companies regularly shipping packages should provide DOT hazardous materials training to relevant employees. This training must be renewed every three years and documented for USPS inspection.
Maintain detailed records of all shipments including contents declarations, packaging certifications, and employee training records. These documents may be required during Postal Inspection Service investigations.
Compliance Management Systems
Implement systematic procedures for:
- Screening all outbound packages against USPS prohibited items lists
- Verifying proper packaging and labeling before shipment
- Maintaining current copies of USPS publications and regulations
- Regular audits of shipping procedures and employee compliance
- Partnering with compliant shipping platforms like ParcelPath that provide built-in compliance checking
Businesses should establish relationships with local postal authorities and participate in USPS business development programs to stay informed about regulation changes. For high-value shipments, implementing indirect signature required services provides additional security and delivery confirmation.
For small businesses and individual shippers, ParcelPath offers discounted USPS rates with compliance guidance built into the platform, helping avoid costly violations while saving 60-89% off retail shipping rates.
Frequently Asked Questions
Can I ship lithium batteries internationally through USPS?
Lithium batteries face stricter international restrictions than domestic shipping. Lithium-ion batteries are limited to 100 watt-hours for air transport internationally, and lithium metal batteries are often prohibited entirely for international air shipments. Always verify destination country restrictions before shipping.
What happens if USPS finds prohibited items in my package?
USPS will seize packages containing prohibited items and may initiate criminal investigations. You could face federal charges, fines up to $250,000, and imprisonment depending on the violation. The package will not be delivered or returned to you.
Are there quantity limits for perfume and cologne shipping?
Yes, perfumes and colognes containing alcohol are limited to ground shipping only with quantity restrictions. Personal use shipments are typically limited to one liter total, while commercial shipments require proper hazardous materials certification and labeling.
Can businesses ship prescription medications through USPS?
Only Drug Enforcement Administration (DEA) registered distributors can ship prescription medications through USPS to verified recipients. Individual patients cannot mail personal prescription medications to others, even family members.
What packaging is required for hazardous materials as of 2026?
Starting January 27, 2026, all hazardous materials require rigid outer packaging with specific strength ratings. Packages under 20 pounds need ECT 32 or 200-pound burst strength, while packages over 20 pounds require ECT 44 or 275-pound burst strength.
Do USPS shipping restrictions apply to military mail (APO/FPO)?
Military mail follows the same USPS restrictions with additional Department of Defense regulations. Some items acceptable for domestic civilian mail may be prohibited for military addresses due to operational security and safety requirements.
This article is part of our comprehensive USPS guide, covering key topics like USPS Services and Shipping Options. Explore more in our Shipping Services and Solutions hub. ParcelPath helps you find the best shipping solutions for any need.
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Part of our USPS Services guide. Related: Ground Advantage, USPS Priority Mail, Priority Mail Express.
