When a person sneezes, he should say Alhamdulillah (as reported in the Hadith) or he may recite the following dua:
اَلْحَمْدُ لله عَلَى كُلِّ حَالٍ
All praise belongs to Allah Ta’ala in all conditions
عن أبي هريرة، عن النبي صلى الله عليه وسلم قال إذا عطس أحدكم فليقل الحمد لله على كل حال وليقل أخوه أو صاحبه يرحمك الله ويقول هو: يهديكم الله، ويصلح بالكم (سنن أبي داود، الرقم : 5033)
Hazrat Abu Hurairah (radhiyallahu anhu) reports that Rasulullah (sallallahu alaihi wasallam) said, “When one of you sneezes, he should say, الحمد لله على كل حال (All praise belongs to Allah Ta’ala in all conditions).
(In response), his brother or his companion should say, يَرْحَمُكَ الله (May Allah Ta’ala have mercy on you).
When his brother or companion says يَرْحَمُكَ الله then the one who sneezed should make dua for him saying, يَهْدِيكُمُ اللهُ وُيُصْلِحُ بَالَكُم (May Allah Ta’ala guide you in deen and dunya and improve your present condition in deen and dunya).