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Last updated
Short answer
Microwave sterilization uses microwave energy, usually at 2450 MHz, to heat a load until microorganisms are inactivated. In healthcare, the CDC disinfection and sterilization guideline describes microwaves as used for disinfecting items such as soft contact lenses and dental instruments, and states that microwaves used for sterilization of medical devices have not been FDA cleared.
Definition and scope
Microwaves are radio-frequency waves, usually used at a frequency of 2450 MHz. In the CDC’s Guideline for Disinfection and Sterilization in Healthcare Facilities (2008, still hosted by CDC), microwave treatment appears as its own section alongside steam, dry heat, ethylene oxide and other methods. The guideline treats two different outcomes separately: disinfection of specific compatible items, and sterilization of medical devices. This page keeps those apart because the regulatory position is different for each.
For the wider picture of how sterilizing methods are grouped and chosen, see the guides on sterilization technology and low-temperature sterilization method selection.
How microwave treatment works
The CDC guideline explains that the friction of water molecules in an alternating electrical field generates heat. It also notes that some authors believe the effect of microwaves depends on the heat produced, while others postulate a nonthermal lethal effect. The guideline does not settle that question.
The studies it cites used a home-type microwave oven (2.45 GHz) and reported complete inactivation of bacterial cultures, mycobacteria, viruses and Geobacillus stearothermophilus spores within 60 seconds to 5 minutes, depending on the challenge organism. A separate cited study on Mycobacterium bovis found complete destruction with 4 minutes of exposure at 600 W and 2450 MHz. Another study cited by the guideline found that higher-power microwaves in the presence of water may be needed for sterilization.
Uses the CDC guideline lists
The guideline states that microwaves are used in medicine for disinfection of the following items. Each row below is taken directly from that sentence.
| Item | Treatment named by the CDC |
|---|---|
| Soft contact lenses | Disinfection |
| Dental instruments | Disinfection |
| Dentures | Disinfection |
| Milk | Disinfection |
| Urinary catheters for intermittent self-catheterization | Disinfection |
For catheters, the guideline cites a study in which E. coli, Klebsiella pneumoniae and Candida albicans were eliminated from red rubber catheters within 5 minutes.
Where it matters for labs, clinics and supply decisions
The checklist below condenses the conditions the CDC guideline attaches to microwave results. It is useful when deciding whether microwave treatment could be considered at all, or whether a validated method is needed instead.
- Regulatory status. Microwaves used for sterilization of medical devices have not been FDA cleared (CDC guideline). The FDA’s own page on sterilization for medical devices lists moist heat (steam), dry heat, radiation, ethylene oxide gas and vaporized hydrogen peroxide; microwave is not listed on that page.
- Material compatibility. Microwaves must only be used with products that are compatible, for example products that do not melt.
- Test conditions change the result. The guideline says effectiveness for different sterilization and disinfection purposes should be tested and demonstrated, because conditions such as the presence of water and microwave power affect the results.
- Uneven energy. Home-type ovens may not distribute microwave energy evenly over an entire dry device. There may be hot and cold spots on solid medical devices, so some areas may not be sterilized or disinfected.
Where a sterilization claim must be demonstrated, the general principles in sterilization validation and the concept of sterility assurance level apply. For heat-sensitive plastics specifically, see which plastics are autoclavable.
Common misunderstandings
Microwave disinfection is not the same as FDA-cleared device sterilization
The CDC guideline lists microwave disinfection uses for a handful of item types, but it separately states that microwave sterilization of medical devices has not been FDA cleared. A published laboratory result showing organism kill in a microwave oven is not the same as a cleared sterilization process.
Microwave-energy gas plasma is a different technology
The same guideline notes that gas plasma sterilizers use radio-frequency or microwave energy to excite a gas. That is a distinct sterilization process from heating a load directly with microwaves, and the two should not be conflated.
Microwave sterilization bags
The CDC guideline section discussed here concerns healthcare microwave treatment. It does not evaluate products sold as microwave sterilization bags, and neither does this page. Any such product comes with its own manufacturer instructions, which are the place to look for its intended use.
Frequently asked questions
Is microwave sterilization FDA cleared for medical devices?
No. The CDC guideline states that microwaves used for sterilization of medical devices have not been FDA cleared. The FDA page on sterilization for medical devices lists moist heat (steam), dry heat, radiation, ethylene oxide gas and vaporized hydrogen peroxide, and does not list microwave.
What does the CDC say microwaves are used for in medicine?
Disinfection of soft contact lenses, dental instruments, dentures, milk and urinary catheters for intermittent self-catheterization, provided the products are compatible with microwaves, for example that they do not melt.
Why do microwave results vary?
The guideline says test conditions such as the presence of water and microwave power affect results, and that home-type ovens may not distribute energy evenly over a dry device, leaving hot and cold spots.
Are microwave sterilization bags covered by the CDC guideline?
The section described on this page does not evaluate them. Follow the manufacturer instructions for any such product.
Is gas plasma sterilization the same as microwave sterilization?
No. Gas plasma sterilizers use radio frequency or microwave energy to excite a gas, which is a different process from heating a load directly with microwaves.
Sources
- CDC, Guideline for Disinfection and Sterilization in Healthcare Facilities (2008), section on microwave; checked 2026-10-29. Index page: CDC disinfection and sterilization guidelines.
- FDA, Sterilization for Medical Devices; checked 2026-10-29.
