Not that I’m aware of but why swallow something that may have side effects. Safer to wear something on your skin or at least your clothing. I find lavender scent is something they don’t care for. But not lavender with vanilla mixed in it. Or as @si3tech suggested.
Avoid certain foods like bananas. It attracts them and dark clothing or heavy clothing that will make your body hotter. The heat from your body really attracts them and carbon dioxide you breathe out. Nothing to be done about breathing though.
I read that allicin found in garlic repels most mosquitos and fleas. So you can try eating plenty of garlic but you will probably repel more than just mosquitos.
I’m not aware of pills you can take that will stop mosquitos biting. There are pills that reduce the chance of you getting malaria but they can have side effects.
No, because mosquitos are attracted to the carbon dioxide you exhale. Any liquid mosquito repellants have chemicals or oils that are strong enough to cover/distract from the smell of you and your exhaled carbon dioxide. You cant possibly exude a chemical smell like that. You can try chewing a clove of garlic in you mouth perhaps, but that sounds worse than being bitten.