Although it may be tempting to buy pain relievers online without a prescription, it is best not to do so. Most countries, such as the United States, have regulations requiring a prescription for most types of pain medications, especially opioids and other strong pain medications. This is to ensure that medications are used safely and appropriately under the supervision of a doctor. For example, if a website sells pain relievers and does not ask you for a prescription, be wary. Such websites may be running illegal businesses and may sell counterfeit or toxic products such as prescription drugs. As for the fact that some websites are purchasing controlled substances, make sure the pharmacy has a prescription for the medication.