The things that void your fasting, scholars say, are seven. So, memorize them and then you don’t have to worry about anything else. Because now you know that these seven nullify your fast, so anything else does not.
1- Eating and Drinking
Anything that goes into your stomach and through the mouth or through the nose, then this nullifies your fasting. Even if you swallow a stone, it nullifies your fasting.
2- Whatever Takes the Role of Food and Drink
Such as the IV, if you have galactose for example that you can live for 3-4 days without eating and drinking, just because of this IV is going into your veins, this nullifies your fasting.
This means that if I take antibiotics, voltarin shots, insulin, penicillin… anything that does not nourish me, and not take the role of eating and drinking, this doesn’t nullify your fasting.
So, if someone says: “I have to take vaccines, does it affect my fasting?”
No, it doesn’t.
“I have to extract a tooth and the doctor gives me anesthesia, does it affect my fasting?”
The answer is, no.
3- Vomiting Intentionally
I ate too much, I have something going on, I don’t like it, I put my finger or smell something and I vomit intentionally, this voids my fast.
If I ate too much and I feel disturbed and all of a sudden without me helping it, I’m vomiting. This is unintentional; it doesn’t affect my fast.
This is an issue of dispute among scholars. So, the most authentic opinion it’s safer not to cup while fasting. Cupping is having scratches and slashes on the back of your neck or on your shoulders and then extracting the rotten blood.
It’s a form of healing and medication. The Prophet Muhammad (peace be upon him) encouraged it. But during fasting refrain from it because it’s an issue of dispute.
However, taking samples of your blood for the hospital is totally permissible. Bleeding from your gum while the dentist is working this does not affect your fasting; try not to swallow it.
Donating blood, if it wears you down and it’s a pint or two, in this case make it after Maghrib (after iftar time). And if you don’t have the possibility to make it after Maghrib, then do it and make up for that day.
Any person ejaculating, while he’s awake of course, because this is different than nocturnal emission. When you have wet dreams, when you ejaculate while sleeping, this doesn’t affect your fast at all. But if you do it intentionally, while awake by looking at something or masturbating, this nullifies your fasting.
This is the highest of all. It nullifies your fasting and you have an expiation for it.
7- The Blood of Menses or Postnatal Bleeding
If these two exist, then the fast is void; even if it’s seconds before the adhan of Maghrib.
Now, if you look at toothpaste and look at these seven categories, you will find that as long as it doesn’t go into your throat you’re in the clear.