Pain The weak<unk>  codeine , in low doses and combined with one or more other drugs, is commonly available without a prescription and can be used to treat mild pain. Other<unk> s are usually reserved for the relief of moderate to severe pain. Acute pain<unk> s are effective for the treatment of acute pain (such as pain following surgery). For immediate relief of moderate to severe acute pain,<unk> s are frequently the treatment of choice due to their rapid onset, efficacy and reduced risk of dependence. However, a new report showed a clear risk of prolonged<unk>  use when<unk>  analgesics are initiated for an acute pain management following surgery or trauma. They have also been found to be important in palliative care to help with the severe, chronic, disabling pain that may occur in some terminal conditions such as cancer, and degenerative conditions such as rheumatoid arthritis. In many cases<unk> s are a successful long-term care strategy for those with chronic cancer pain. Just over half of all states in the US have enacted laws that restrict the prescribing or dispensing of<unk> s for acute pain. Chronic non-cancer pain Guidelines have suggested that the risk of<unk> s is likely greater than their benefits when used for most non-cancer chronic conditions including headaches, back pain, and fibromyalgia. Thus they should be used cautiously in chronic non-cancer pain.Responses to Okie's perspective: If used the benefits and harms should be reassessed at least every three months. In treating chronic pain,<unk> s are an option to be tried after other less risky pain relievers have been considered, including paracetamol/acetaminophen or NSAIDs like ibuprofen or naproxen. Some types of chronic pain, including the pain caused by fibromyalgia or migraine, are preferentially treated with drugs other than<unk> s. The efficacy of using<unk> s to lessen chronic neuropathic pain is uncertain.<unk> s are contraindicated as a first-line treatment for headache because they impair alertness, bring risk of dependence, and increase the risk that episodic headaches will become chronic.<unk> s can also cause heightened sensitivity to headache pain. When other treatments fail or are unavailable,<unk> s may be appropriate for treating headache if the patient can be monitored to prevent the development of chronic headache.<unk> s are being used more frequently in the management of non-malignant chronic pain. This practice has now led to a new and growing problem with addiction and misuse of<unk> s. Because of various negative effects the use of<unk> s for long-term management of chronic pain is not indicated unless other less risky pain relievers have been found ineffective. Chronic pain which occurs only periodically, such as that from nerve pain, migraines, and fibromyalgia, frequently is better treated with medications other than<unk> s. Paracetamol and nonsteroidal anti-inflammatory drugs including ibuprofen and naproxen are considered safer alternatives. They are frequently used combined with<unk> s, such as paracetamol combined with oxycodone (Percocet) and ibuprofen combined with hydrocodone (Vicoprofen), which boosts the pain relief but is also intended to deter recreational use. Other Cough Codeine was once viewed as the "gold standard" in cough suppressants, but this position is now questioned. Some recent placebo-controlled trials have found that it may be no better than a placebo for some causes including acute cough in children. Thus, it is not recommended for children. Additionally, there is no evidence that hydrocodone is useful in children. Similarly, a 2012 Dutch guideline regarding the treatment of acute cough does not recommend its use. (The<unk>  analogue dextromethorphan, long claimed to be as effective a cough suppressant as codeine, has similarly demonstrated little benefit in several recent studies.) Low dose morphine may help chronic cough but its use is limited by side effects. Diarrhea and constipation In cases of diarrhea-predominate irritable bowel syndrome,<unk> s may be used to suppress diarrhea. Loperamide is a peripherally selective<unk>  available without a prescription used to suppress diarrhea. The ability to suppress diarrhea also produces constipation when<unk> s are used beyond several weeks. Naloxegol, a peripherally-selective<unk>  antagonist is now available to treat<unk>  induced constipation. Shortness of breath<unk> s may help with shortness of breath particularly in advanced diseases such as cancer and COPD among others. However, findings from two recent systematic reviews of the literature found that<unk> s were not necessarily more effective in treating shortness of breath in patients who have advanced cancer. Hyperalgesia<unk> -induced hyperalgesia (OIH) has been evident in patients after chronic<unk>  exposure.
Opioid
Heroin
Synthetic cannabinoids
Nicotine
Phencyclidine
Cocaine 
Cocaine
Benzphetamine