We understand your concern about hair loss and your desire to help others by donating blood. We commend your unselfish desire to prioritize cures for blindness and cancer above your personal wishes.
Firstly, let's remember God's will is always the best. The Bible tells us that God knows even the number of hairs on our head. Fear not therefore: for there is nothing covered, that shall not be revealed; and hid, that shall not be known. Therefore whatsoever ye have spoken in darkness shall be heard in the light; and that which ye have spoken in the ear in closets shall be proclaimed upon the housetops. Fear them not therefore: for there is nothing covered, that shall not be revealed; and hid, that shall not be known. But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment. For by thy words thou shalt be justified, and by thy words thou shalt be condemned. Are not two sparrows sold for a farthing? and one of them shall not fall on the ground without your Father. But the very hairs of your head are all numbered. Fear ye not therefore, ye are of more value than many sparrows. (Matthew 10:26-31 WEB).
Regarding your use of medication, it's important to note that God wants us to take care of our bodies, which are temples of the Holy Spirit. Or don't you know that your body is a temple of the Holy Spirit who is in you, whom you have from God? You are not your own, for you were bought with a price. Therefore glorify God in your body and in your spirit, which are God's. (1 Corinthians 6:19-20 WEB). While it's good to want to preserve your hair, be cautious not to become vain or overly focused on physical appearance.
Your desire to give blood to help others is commendable. It reflects the love that God has for us and wants us to have for others. A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another. By this shall all men know that ye are my disciples, if ye have love one to another. (John 13:34-35 WEB).
Let's pray together for your only if it be God's will:
Heavenly Father, we come before you in Jesus' name to lift up our brother/sister. We pray for your will to be done in his/her life, including his/her concern about hair loss. If it is your will, please provide solutions and treatments that can help with this issue. We also pray for his/her desire to give blood again, that you would make a way for this to happen if it is your will.
We thank you, Father, for hearing our prayers. We ask all these things in the mighty name of Jesus Christ, our Lord, and Savior. Amen.
Lastly, remember that God looks at the heart, not our outward appearance. The LORD does not see as man sees; for man looks on the outward appearance, but the LORD looks on the heart. (1 Samuel 16:7 WEB). Continue to cultivate a beautiful heart for God, and your outer beauty will shine as well.