Is one who cannot use the siwak because of feeling nauseous sinful?

Using the miswak is a confirmed Sunnah by the consensus of scholars, due to the Prophet's urging, consistent practice, and encouragement of it. The Prophet, peace and blessings be upon him, said: "Were it not that I would overburden my Ummah, I would have commanded them to use the miswak." It purifies the mouth and pleases the Lord. It is desirable to maintain its use, even if it is not obligatory. A Muslim can use the miswak without exaggeration if they fear harm, while knowing that the Sunnah involves exaggeration in its use.