Some illnesses and/or their associate remedies will prevent you from studying due to extreme symptoms like pain or intense drowsiness. In these cases, prioritize getting better over getting a good exam score and be realistic about what, if anything, is achievable. In other cases, although you feel rotten and can't get much further from your bed than the bathroom, you may still be able to read, do online test questions, or use other study methods to keep on learning.  Let your teacher know as soon as possible if you’ll miss class time due to an illness. Reach out by email or your teacher’s preferred method of communication. If you are seriously ill, most schools will offer alternative arrangements for exams. Go to the doctor immediately to seek help and get an official note that can verify your illness to school officials. Being sick can make studying feel like a hopeless endeavor and increase your anxiety about exams. Adopting an optimistic mindset (for instance, by reminding yourself that you’re doing your best in spite of the circumstances) and avoiding destructive thoughts (such as, “I’m so sick, I’ll never be able to pass this exam”) will help you pull through a tough time. Keep in mind that any revision that you’re able to do is going to be useful, no matter how minimal it is. It’s better to study as best as you’re able to, than to give up or not study at all. To study effectively, you need an environment with minimal distractions; this is even truer when you’re sick and distracted by all your symptoms. Take some time to prepare an appropriate space that’s conducive to studying and has everything you need at your fingertips.  Minimize your distractions. Find a quiet place away from other people. Turn off your phone, television, or other electronic devices that you do not need for studying. Make sure that you’re comfortable. Avoid studying in bed since it’s most likely going to make you sleepy, but do pick a seating arrangement and position that will be relaxing during the length of your study session....

TL;DR in Indonesian:
Pertimbangkan tingkat keseriusan penyakit Anda. Miliki sikap mental dan perilaku yang positif. Ciptakan lingkungan belajar yang kondusif. Konsumsi makanan yang sehat dan seimbang. Minum sebanyak mungkin cairan jernih, terutama air putih. Jangan mengonsumsi kafeina secara berlebihan. Jangan luap mengonsumsi obat dan vitamin yang diperlukan. Beristirahatlah sebanyak mungkin.