Do EMF stickers work? What the evidence says

Updated November 9, 2026

No. US regulators have said for more than 20 years that stickers and small shields don't meaningfully cut what a phone gives off, and lab tests of the stickers agree. In a 2025 test of 11 anti-radiation stickers, none lowered the phone's measured RF power, and the phone put out more power with every one of them attached. If you want less exposure from your phone, distance does that job for free.

This page covers one question, whether a sticker reduces radiofrequency (RF) exposure. It isn't medical advice. On health, the FDA says "the weight of scientific evidence has not linked cell phone radio frequency radiation with any health problems" (FDA cell phone page, current as of 2021).

Do anti radiation stickers really work?

The FTC, the FCC and the FDA have each said no. In June 2011 the FTC told consumers that "there is no scientific proof that so-called shields significantly reduce exposure from cell phone emissions." Its September 2011 alert went further. A product that covers only the earpiece or another small part of the phone is "totally ineffective," since the entire phone emits, and a shield that interferes with the signal can make the phone draw more power to reach the base station.

The FCC's RF safety FAQ says studies show these devices "generally do not work as advertised" and "may actually increase RF absorption in the head," because getting in the way of the signal forces the phone to raise its power.

A 2020 FDA consumer page used nearly the same words and added that the agency "considers these claims to be bogus." FDA has since folded that page into its cell phone hub, so we quote an archived copy.

What happened to the "99%" patches of the early 2000s

On February 20, 2002, the FTC charged two companies that sold patches made to go over a phone's earpiece. The FTC alleged that the companies falsely claimed their products blocked up to 97% or 99% of the radiation a phone emits, and that they "lacked a reasonable basis to substantiate their claims." The complaints also said the ads left out that "the vast majority" of a phone's electromagnetic energy comes from the antenna and parts other than the earpiece. The cases came from the Good Housekeeping Institute, whose own tests found the products "did not reduce radiation exposure from cellular telephones." These were allegations, for the courts to decide.

Two more patch sellers settled in August 2003. Their orders require them to disclose that most of a phone's energy comes from parts other than the earpiece, and one agreed to pay $342,665 back to buyers.

What lab tests of stickers found

In 2003, researchers at Motorola tested nine small shields "made to adhere to the case of mobile phones" (Bioelectromagnetics, 2003). Five were popular products whose ads, the paper says, typically claimed up to 99% effectiveness. The team held the phone against a head model and measured SAR with and without each shield at 914 and 1880 MHz, the way the company tested phones for compliance. Peak SAR "did not change by any statistically significant amount," and the spot where it peaked didn't move. (We could read only the abstract.)

In 2025, a team based at the Radiation Protection Institute of the Ghana Atomic Energy Commission tried 11 anti-radiation stickers, three samples of each, on a basic phone and a smartphone (Journal of Science and Technology, 2025). Each sticker went on the back of the phone, as its instructions said. They measured the phone's emitted RF power with and without it, dialing and receiving calls, with distance, call time and battery charge held constant. None lowered the phone's output; with all 11, measured power went up.

Read the direction of those bars more than their length. The data were heavily skewed, with a few very large readings pulling the averages up, so the authors say the median of all their measurements, an attenuation of -99.91%, represents the results better than the mean. In plain terms, the median measurement had the phone's power roughly doubling. The study measured emitted power, not SAR, and the authors say an SAR test would add to their findings. It is one lab and two phones, but it points the same way as the 2003 test and the agencies.

Why would a sticker make a phone work harder?

A phone is a two-way radio. It has to reach a tower to carry your call, and it adjusts its own transmit power to get there. Phones "constantly vary their power to operate at the minimum power necessary for communications," the FCC says in its consumer guide on wireless devices, and maximum power "occurs infrequently." The IEEE's Committee on Man and Radiation (COMAR) adds that the base station sets the handset's power, which "can vary from moment to moment."

If a sticker blocks almost nothing, it changes almost nothing. If it blocked enough RF to matter, it would also get in the way of the phone's own connection, and COMAR warns that a device that interferes with that link "may cause the handset to increase its output." The 2025 authors suggest the same explanation. FDA's 2020 page put the worst case bluntly: such products "might prevent your phone from finding signal when you most need to make a call for your safety."

Why do EMF meter demos look convincing?

Maybe you've seen a video where a handheld meter reads high next to a phone, then drops once a sticker goes on. We can't judge any particular video, but the sources explain why such a reading can move for reasons unrelated to the sticker.

Distance comes first. The National Cancer Institute (NCI) says "the SAR decreases very quickly as the distance to the exposure source increases." Move the meter a little, and the number changes. Position matters even in formal testing: the FCC tests each phone "in various specific positions" against a model head and body, and notes that a phone's highest value may come from a position its owner rarely uses.

Timing matters too. A phone's power can change from moment to moment, and the FTC notes that phones give off more when transmitting than when receiving, so two readings a few seconds apart can differ with nothing else changed.

The Ghana lab fixed each phone 0.3 cm from its measuring antenna so that distance couldn't skew its numbers. COMAR says measurements made outside the standard procedures "will be hard to interpret and are likely to be unreliable." Its bar for a valid test is SAR measured with the phone at a constant power level, with and without the device, plus a check on whether the device disrupts the phone's link to the tower. A meter in the air near a phone isn't measuring SAR, and a short clip can't prove the phone's power stayed constant.

What actually lowers exposure from a phone?

We understand the appeal of a sticker: you put it on once and stop thinking about it. What works means changing a habit or two. Every agency we cite comes back to distance, and the FCC puts it plainly: "The closer the wireless device is to your body, the more energy you will absorb." The steps the FTC, FCC, FDA and NCI list, in our words:

• Put longer calls on speakerphone or use a headset. The FCC says wired and wireless earpieces both move "the greatest source of RF energy" away from your head and "can greatly reduce total exposure to the head." NCI notes that Bluetooth headphones and earbuds typically transmit at 10 to 400 times lower power than a cell phone. Wired earbuds link soon have no radio of their own, though the FCC says a wired earpiece may conduct some energy to the head.
• Text instead of calling when you can, but never while driving.
• On a weak signal, wait for a better one before a long call. The FTC says a phone on a weak signal "works harder."
• Keep calls shorter.
• When you aren't using the phone, keep it a bit farther from your body.

Don't shop by SAR number. Every phone sold in the US has to stay at or under the FCC limit of 1.6 W/kg, averaged over one gram of tissue, at its highest possible power. In normal use phones typically run at much lower power than in that test, so the FCC says comparing SAR between phones "may be misleading." The FTC's 2011 alert agreed.

A Faraday pouch link soon encloses the whole phone, so it can cut the phone off from the network while stored, and then the phone can't ring. NIST's 2014 mobile forensics guide warns that these containers "may attenuate the radio signal, but not necessarily eliminate it completely," that a badly sealed bag can let the network in, and that a phone unable to connect raises its signal strength to maximum and drains its battery. The same guide lists airplane mode and switching the phone off as the other ways to isolate it, and both are free. If you buy a pouch anyway, seal the phone inside and call or text it from another phone. If it rings, the pouch isn't blocking.

One caveat. The FCC says it "does not endorse the need for these practices," and FDA's 2020 page said "there is no established health benefit from reducing an individual's RF exposure from cell phones." The steps are there for people who want less exposure anyway.

A short checklist before you buy

• A percentage "blocked" on the package means little without an SAR test at constant power, with and without the sticker.
• A meter video can't show that distance, position and power stayed the same.
• For a long call, use speakerphone or earbuds.
• On one bar of signal, text or wait.
• To take the phone off the network overnight, use airplane mode or switch it off. Buy a pouch only if it passes the call test.
• When comparing phones, give the SAR figure little weight.

If a sticker is already on your phone, you can peel it off. Nothing in the evidence above says you'd lose anything. Then put your next long call on speaker.