Spanish people are Europe's heaviest users of services like WhatsApp but the thumb-numbing habit could have unanticipated health consequences.
Inés M. Fernandez-Guerrero recorded the case in the March 22 edition of The Lancet.
"A 34-year-old emergency medicine physician, 27 weeks pregnant, presented with bilateral wrist pain with sudden onset upon waking up one morning. She had no history of trauma and had not engaged in any excessive physical activity in the previous days," she wrote.
Fernandez-Guerrero, of General University Hospital in Granada went on to note, "The patient … responded to messages that had been sent to her on her smartphone via WhatsApp instant messaging service. She held her mobile phone, that weighed 130g, for at least 6h. During this time she made continuous movements with both thumbs to send messages."
She added: "The diagnosis for the bilateral wrist pain was WhatsAppitis. The treatment consisted of non-steroidal anti-inflammatory drugs and complete abstinence from using the phone to send messages."
WhatsApp may have entered the Spanish lexicon, with the verb 'wasapear' (meaning 'to send a WhatsApp message') being given the thumbs-up by notable language foundations.
But doctors warn that too much of a good thing could be painful — as they discovered in the past with 'Nintendinitis'.
"Tenosynovitis caused by texting with mobile phones could well be an emerging disease. Physicians need to be mindful of these new disorders," Fernandez-Guerrero concluded.