While on Accutane, it is important to avoid blood donation due to the risk of birth defects if the blood is given to a pregnant woman. Unprotected sexual activity should be avoided to prevent pregnancy due to the high risk of teratogenic effects. Additionally, you should not take tetracycline antibiotics concurrently with isotretinoin, as this combination can increase the risk of intracranial hypertension.
Since your blood will contain isotretinoin, you are advised not to donate blood to mitigate the risk of being given to a pregnant woman and causing irreversible fetal damage in utero. Similarly, unprotected sex could lead to a pregnancy and could cause irreversible fetal damage in utero.
While some people may think using another anti-acne medication, such as tetracyclines on top of their accutane, could further improve the appearance of their acne, it can cause high pressure around the brain, which could lead to vision changes and headaches.