Aspirin or paracetamol
BMJ Group Medical Reference
Painkillers are likely to work for period pain. They include aspirin and paracetamol. You can get these over the counter.
The research on aspirin and paracetamol isn't as good as it is for nonsteroidal anti-inflammatory drugs ( NSAIDs), so we can't say whether they will definitely work, or which is better.  
Painkillers can have side effects.
Aspirin can sometimes cause an upset stomach, a rash, and a small amount of blood in your stools.  Your blood may appear thinner, or you may not stop bleeding as quickly if you cut yourself.
It's important to take the recommended dose of paracetamol. Taking too much paracetamol can damage your liver.
Your liver is on the right side of your body, just below your ribcage. Your liver does several things in your body, including processing and storing nutrients from food, and breaking down chemicals, such as alcohol.
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