The phrase "constantly warning" is correct and usable in written English.
It can be used when describing a situation where someone or something is repeatedly or continuously giving warnings about a particular issue or danger.
Example: "The safety signs were constantly warning visitors about the slippery floors."
Alternatives: "repeatedly cautioning" or "frequently alerting".
"These are the same provocateurs that the authorities in Moscow are constantly warning about".
Tancredo appeared on talk radio constantly warning of the dangers posed by illegal immigration.
At this time of year, it feels like people are constantly warning you they are "coming down" with a cold.
"In my relationship now, I'm constantly warning, this is what you have to be careful of, you have to know when to shut it off," she said.
It is valid, but consumers' concerns are only natural, particularly as experts are constantly warning shoppers never to hand over card details in such circumstances.
I have been constantly warning for years that this practice – which is becoming increasingly widespread – is a danger to our sport," said Platini.
She is also taming her vocal style, normally a flood warning constantly in effect, to try out jazz phrasing that recalls Abbey Lincoln.
Sánchez also said that he is being constantly moved, without warning.
Clemens Fuest, president of the well-known Ifo-Institute for economic research in Munich, is constantly sending out warning signals.
We constantly see articles warning ravers to stay away from pills bearing logos like purple pumpkins, supermans, white Mitsubishis, and most recently during ADE week, the dangerously high MDMA-leveled pills that were reportedly cut with the logo of the iconic dutch festival itself.
Russian officials constantly give warning of planned terrorist outrages by Chechens.The most significant feature of the election is not the all-but-certain result but the comprehensive way in which the Kremlin has managed to control the campaign.
