Millions of people turn to over-the-counter drugs for relief when they have a headache or minor aches and pains. Others are prescribed pain medication or even (in some states) have turned to medical marijuana for pain relief. Every medication, however, can carry risks. Here's a guide to some of the most commonly used pain relief medications: 
Aspirin is one of the cheapest and oldest manufactured painkillers on the market. German-born scientist Felix Hoffman is credited with creating and popularizing what was then known as acetylsalicylic acid in 1899 to help ease his dad's arthritis pain. Today, it is used to ease minor aches and headaches. It works by reducing the substance in the body that causes inflammation and fever. Doctors also tell some adults to take an aspirin daily to help prevent a heart attack or stroke. People with bleeding conditions like ulcers or cardiovascular troubles like asthma are often advised to take another painkiller, as it may make those conditions worse. Some Americans are also allergic to aspirin. Americans consume more than 15 billion aspirin tablets a year. 
Ibuprofen falls into the class of drugs known as NSAIDs (nonsteroidal anti-inflammatory drugs). Sold under brand names including Motrin or Advil, it's used to treat minor aches and pains and reduce fever. It may be prescribed in stronger doses. It comes in tablet form as well as in chewable tablets, liquid suspensions and concentrated liquid drops. People who take NSAIDs may have a higher heart attack or stroke risk than those who do not, according to the National Institutes of Health. The medication can also cause ulcers, bleeding or holes in the stomach and intestine for some people. The risk may be higher if you take NSAIDs for a long time, are older or in poor health, and have three or more alcoholic drinks per day. 
This compound can ease minor muscle, back, tooth and joint pain and reduce fever. Sold under brand names such as Tylenol, Liquiprin and Panadol, it works by regulating the part of your brain that controls your body's temperature and inhibits the synthesis of prostaglandin in the central nervous system. People who can't take aspirin can often take this as it is less likely to hurt your stomach and does nothing to ease inflammation. People with liver disease are advised not to take it. Acetaminophen is also used in other drugs. Too much of the drug can cause rashes, liver failure and even death. 
There's been a growing acceptance of marijuana as a legitimate pain reliever, although the American Medical Association last year affirmed its opposition (PDF) to its legalization. Doctors in some states may prescribe it to ease chronic pain that comes from arthritis, migraines, Crohn's disease or other ongoing pain issues where other medicines have failed. It works by blocking the pain sensations felt by peripheral nerves. The cannabinoids in marijuana bind to endocannabinoid receptors throughout the body and can reduce pain (but also give the feeling of being high). Some research shows that it can also slow cancer development and increase appetite. Twenty states and the District of Columbia allow some legal use of marijuana, mostly for medicinal purposes. 
Hydrocodone is available only in combination with other ingredients, with different products prescribed for different uses. Some products are used to relieve moderate to severe pain, while others combat a cough, according to the National Institutes of Health. An opiate (narcotic) analgesic, hydrocodone relieves pain by changing the way the brain and nervous system respond to it. It may be habit-forming, and abuse of drugs, including hydrocodone, has become a concern in recent years. The Food and Drug Administration has proposed moving hydrocodone combination pills, known as opioids, from a Schedule III to Schedule II. Patients would have to have a written prescription from a doctor -- as opposed to a prescription over the phone -- to access them, and no refills would be allowed unless patients check in with their doctors. 
Fentanyl is a prescription-only pain medication often given to cancer patients. They must be at least 18 years old to take it, or at least 16 for lozenges branded as Actiq, and they should also be taking regular doses of another narcotic pain medication. Patients must also be accustomed to the effects of narcotics. Fentanyl itself is a narcotic and changes the way the brain and nervous system respond to pain, according to the National Institutes of Health. This drug comes in the form of a lozenge, a tablet under the tongue, a film and a buccal (between the gum and cheek) tablet, as well as in injectable form. It is designed for sudden episodes of pain and should not be used more than four times a day. Overdose can cause drowsiness, dizziness, confusion, breathing problems or smaller pupils. 
Patients take morphine for moderate to severe pain. It is an opiate (narcotic) analgesic and changes the way the brain and nervous system react to pain. Forms of morphine include tablet and solution, which are taken every four hours, as needed. Controlled- or extended-release tablets and controlled- or sustained-release capsules are for patients who need around-the-clock pain relief. Morphine can also be found as a morphine sulfate injection, as added to an IV fluid that drips through a needle or catheter, or injected into a large muscle. Morphine overdose can cause serious consequences such as breathing problems, loss of consciousness, sleepiness, slow heartbeat, blurred vision, nausea and fainting, according to the National Institutes of Health. Morphine may also be habit-forming. 
Propofol, also known as Diprivan, became infamous when pop star Michael Jackson died after overdosing on the drug while using it as a sleep aid. The drug is typically administered intravenously by medical professionals for anesthetic purposes, such as when a patient is undergoing surgery. It's not approved to treat sleep disorders, according to the Food and Drug Administration. The drug itself does not provide pain relief but renders a patient unconscious. A patient wakes up almost immediately after an infusion is stopped, experts say. Propofol lowers blood pressure and suppresses breathing, so patients' heart function and breathing need constant monitoring, according to the Harvard Health Blog. Abuse of propofol in medical circles, however, has been a concern in recent years. - Coalition of health, consumer groups express concern about painkiller Zohydro
- The hydrocodone-based drug is set to be available in March
- One expert says FDA-approved drug is five times more potent than current medications
- "It will kill people as soon as it's released," one doctor says.
Editor's note: For more on Zohydro, tune in to "Sanjay Gupta MD" at 4:30 p.m. ET Saturday and 7:30 a.m. ET Sunday.
(CNN) -- A potent little painkiller is causing a big stir.
A coalition of more than 40 health care, consumer and addiction treatment groups is urging the Food and Drug Administration to revoke approval of the prescription drug Zohydro.
The hydrocodone-based drug is the latest in a long line of painkillers called opioid analgesics. The FDA approved the medication last fall to treat chronic pain, and it is set to become available to patients in March.
"In the midst of a severe drug epidemic fueled by overprescribing of opioids, the very last thing the country needs is a new, dangerous, high-dose opioid," the coalition wrote in a letter to FDA Commissioner Dr. Margaret Hamburg.
"Too many people have already become addicted to similar opioid medications, and too many lives have been lost."
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Acetaminophen safe for pregnant women? One addiction expert who signed the letter was more forthright.
"It's a whopping dose of hydrocodone packed in an easy-to-crush capsule," said Dr. Andrew Kolodny, president of the advocacy group Physicians for Responsible Opioid Prescribing. "It will kill people as soon as it's released."
The letter is the latest in a series of entreaties to the FDA related to Zohydro.
In December, 29 state attorneys general sent a similar letter to the FDA. The month before, members of Congress asked the agency to review its decision to approve the drug.
The concerns echoed by all groups are broadly about the drug's potency and abuse potential. They say they fear that Zohydro -- especially at higher doses -- will amplify already-rising overdose numbers.
"This could be the next OxyContin," says a petition on Change.org asking the FDA to reconsider.
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According to the Centers for Disease Control and Prevention, prescription opioid deaths more than quadrupled since 1999 -- there were 4,030 deaths involving the drugs in 1999, compared with 16,651 in 2010.
"You're talking about a drug that's somewhere in the neighborhood of five times more potent than what we're dealing with now," said Dr. Stephen Anderson, a Washington emergency room physician who is not part of the most recent petition to the FDA about the drug. "I'm five times more concerned, solely based on potency."
Both Zohydro's maker, Zogenix, and the FDA assert the drug's benefits outweigh its risks.
"We do not expect the introduction of Zohydro ER (extended release) to increase the overall use of opioids," said Dr. Brad Galer, executive vice president and chief medical officer at Zogenix, in an e-mail. "In fact, prescription data from the last five years shows that total use of ER opioids is constant and independent of new entrants to the market."
Galer said the company will focus its commercial efforts on a small group of doctors with good experience prescribing opioids, so that only appropriate chronic pain patients would receive the drug.
Advocates for pain patients say that concerns about abuse, while valid for some, are not necessarily an issue for those patients.
"We know that a person with pain is not a person who abuses medications," said Paul Gileno, founder and president of the U.S. Pain Foundation, a group that receives some funding in unrestricted grants from the pharmaceutical industry. "A person with pain is a person suffering to get pain relief in order to live a fulfilling life."
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In their petition to the FDA for approval, Zogenix representatives cited examples of patients who might benefit from Zohydro: a 46-year-old male with chronic back and leg pain who had two failed back surgeries; a 52-year-old female with metastatic breast cancer experiencing diffuse pain; a 32-year-old woman with multiple orthopedic fractures.
If Zohydro follows in the footsteps of its opioid-containing predecessors, such a narrow, focused patient group may expand -- to patients with low back pain, fibromyalgia, arthritis or countless other chronic conditions.
"The problem is, it costs a lot of money bringing a drug through clinical trials and then bringing it to market," said Anderson, past president of the Washington chapter of the American College of Emergency Physicians. "You have to anticipate (the drug company) being able to market and get its money back.
"I see this as a marketing ploy where eventually it's 'I've got bigger, I've got stronger, why don't you prescribe this,' and I'm terrified of that."
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Bigger, stronger opioids -- especially those containing hydrocodone -- are a concern. Hydrocodone (Zohydro's sole ingredient) is one of the most frequently prescribed -- and abused -- opioids.
For that reason, in October, the FDA said it intended to shift hydrocodone-containing drugs from Schedule III to Schedule II. That rescheduling (still pending approval by the Drug Enforcement Administration) would mean much stricter dispensing and prescribing rules for hydrocodone-containing products.
At the time of that recommendation, the FDA posted a statement on its website that it "... has become increasingly concerned about the abuse and misuse of opioid products, which have sadly reached epidemic proportions in certain parts of the United States."
A day after announcing the proposed drug schedule change for hydrocodone, the FDA announced Zohydro's approval. It was a confusing juxtaposition, some say.
"Shocking, outrageous and genuinely frightening," said Kolodny of the Physicians for Responsible Opioid Prescribing.
FDA spokeswoman Morgan Liscinsky said that Zohydro's approval was separate and distinct from the agency's recommendation about rescheduling hydrocodone-containing products.
"I find great difficulty (with) the wisdom of the FDA's approval in terms of protecting the public's health," said Dr. Alex Cahana, professor of pain medicine at the University of Washington in Seattle, who was not among those who signed the letter to the FDA. "Risk-benefit thinking suggests that not everything we can do, we should do."
Zohydro will enter the market already classified as a Schedule II -- one reason both the FDA and the drug's maker are confident it will not contribute to the broader overdose problem.
Zohydro's labeling will feature warnings about abuse, addiction and misuse, and Galer said Zogenix is working on an abuse-deterrent version of Zohydro that should become available in three years.
None of those precautions has assuaged concerns. Anderson said that while a small subset of patients may benefit from Zohydro, unleashing such a potent drug in the current environment is unsafe.
"Put more of this kind of drug out on the street and, I'll see more overdoses related to this, no question," Anderson said.
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Water, and lots of it, in view on the approach to Italy's city of canals - one airport among this selection from the PrivateFly.com shortlist. Sit on the right of the aircraft for the best view, says one judge in the poll. 
Dramatically restricted space makes this a teeth-clenching landing, but the view of "Africa, Europe and the Rock" is an "antidote to boring bus-stop airline flights," says another judge. 
"You descend over the Black Sea, watching the city and Olympic Park unfold in front of you, with a beautiful mountain backdrop," writes one fan. 
"The most incredible approach, with views of Guanabara Bay," says a PrivateFly.com voter. 
A landing at this James Bond ("Tomorrow Never Dies") stunt scene -- used by private aircraft -- gets the blood pumping for the Alpine snow action to follow. 
Arriving at this airport used for charter and private flights is "sublime ... in any season, surrounded by banks of pine trees, mountains and a river" reads one commendation. 
A palette of Caribbean Ocean blues spreads out beneath you as you approach this airport named after the island's former reigning monarch. 
The only airport in the world with scheduled runways landing on a beach, Barra's runway is submerged at high tide. 
"You arrive as the African dawn is breaking over one of the continent's most dramatic mountain ranges. Below is the sprawl of squatter shacks that put this natural beauty in perspective," says veteran British travel editor Graham Boynton. 
Informally known as Chek Lap Kok, H.K.'s main airport was built on land specially reclaimed for the purpose. 
Views of Westminster, the London Eye, Tower Bridge, and St. Pauls are possible as you approach this single-runway airport by the Thames. 
It's hard to imagine a more quintessential city view than the cluster of skyscrapers almost scratching your undercarriage as you approach Manhattan. 
There's a "beautiful approach from the north-east over the Alps, then Monaco, or west with the red Estérel Mountains on the left and blue Med on the right," says the aviation journalist Sylvie Peron. 
The plunge into this steep valley containing secluded Bhutan's only international airport is as beautiful as it is challenging -- only eight pilots in the world are qualified to land here. 
