New research shows mobile phone masts do not cause symptoms similar to flu in people who claim to be hypersensitive to radio waves.
Scientists claim the signals emitted are harmless over a short period of time to both "vulnerable" and healthy individuals.
However, the study, one of the largest ever undertaken, has found that some people do feel ill when they know they are being exposed to the waves.
The physical effects range from a feeling that their skin is burning, to nausea, and in some cases people have even moved home to get away from the source.
But their symptoms are likely to be psychosomatic, the experiments show.
Professor Elaine Fox, from the University of Essex, who led the study published online in the journal Environmental Health Perspectives, said the effects could be down to anxiety caused by technophobia.
She added: "We do know there is a very large amount of literature showing that the placebo effect, the power of belief, is very powerful. There's nothing magical about that. There are real clinical, biological effects.
"I'm pretty confident that it's not the electromagnetic field causing these symptoms.
"They might have a headache, and they notice on the train that someone has a mobile phone, so they immediately make the attribution, that it must be the mobile phone causing the problem."