Question: Im confused about painkillers. What should I take & when ?

Painkillers or medically known as analgesic are drugs for treatment of reducing pain.

There is no magic bullets so keep the peace triumvirate of aspirin, paracetamol and ibuprofen to hand.
Aspirin is effective for general pain, while ibuprofen is particularly good for inflammation, but both can irritate the stomach.
Paracetamol is very safe in correct doses and can also be taken with ibuprofen or aspirin.
However, be ware of Codeine, it can cause drowsiness as well as increasing the effect of alcohol. Speaking of which, for hangovers, effervescent paracetamol and ibuprofen with a pint of water is your best plan of attack.

Here is a comparison table summary of popular pain medication. The pain relievers below were ranked by effectiveness for chronic back pain, by a Harvard Study. Each pain medication was rated for effectiveness on a scale of from 1 (aspirin) to 10 (morphine).

Painkiller Comparison Chart From Weakest to Strongest
.    1. OVER - THE - COUNTER (OTC) Pain Medicine
Brand Name (Capitalized)	generic name (not capitalized)	Dose (per pill)	PAIN RELIEF SCORE	Uses According to Label	Best Uses (according to Consumer's Guide)	Problems Caused
Anacin Bayer Bufferin Ecotrin	aspirin (acetylsalicylic acid) NSAID	81 mg 325 mg	1	Minor aches, pains cold, headache, muscular ache	minor aches and pains	aspirin allergy, asthma, stomach bleeding, Reye's Syndrome
Anacin non Excedrin Tylenol	acetaminophen (N-(4-hydroxyphenyl) acetamide)	500 mg	2	Headache	fever, if allergic to aspirin, arthritis, rheumatism, musculo-skeletal	June 2009, again 7-04-06- Tylenol Liver Damage "Tylenol is the No. 1 cause of acute liver failure in the U.S." "[Acetaminophen] is a leading cause of death from pharmaceuticals,"
Vanquish	Combination of aspirin (NSAID), and acetaminophen	325 mg 500 mg	2.25	Headache Muscle ache	headache	same as above not for children and teens
Advil Motrin Nuprin	ibuprofen (2-(4-Isobutyl-phenyl)- propionic acid) (analgesic, antipyretic) NSAID	200 mg	2.5	Aches, pains, colds, toothache, muscle aches, backache, menstrual, fever	fever, muscle ache	aspirin allergy, asthma, upset stomach, not for last trimester
Aleve Naproxen	naproxen sodium (anti-inflammatory) NSAID	220 mg	3	Joint and muscle pain	arthritis, rheumatism, musculo-skeletal	Naproxen heart risk upset stomach, not for nursing mothers
Motrin 800	ibuprofen (analgesic, antipyretic) NSAID	800 mg	3.5	(listed above)	(as above)	(as above)
Actron Orudis	ketoprofen (anti-inflammatory) NSAID	12.5 mg	3.6?	Anti-inflammatory, analgesic	arthritis	Ketoprofen side effects
Notes :	(NSAID= Non-Steroidal Anti-Inflamatory Drug) More Warnings on OTC Drugs: NSAIDS Increase Blood Pressure Aspirin and NSAIDS Cause Stomach Bleeding Resulting In Death NSAIDS Linked to Erectile Disfunction

2. PRESCRIPTION Pain Medicine
Brand Name	generic name	Dose (per pill)	PAIN RELIEF SCORE	Uses According to Label	Problems Caused
Celebrex	celecoxib (COX-2 inhibitor) NSAID	100 mg 200 mg	3.7*	Osteoarthritis, rheumatoid arthritis, short term pain, painful menstruation	Celebrex heart risk stomach bleeding, heart attack, stroke
Ultram	tramadol	50 mg	3.8*	Moderate pain	nausea, constipation, dizziness, headache, drowsiness, vomiting
				* Note: The scores for Celebrex and Ultram are estimates (3.7* and 3.8*). These two drugs did not exist at the time of the study.
Demerol	meperidine HCl	50 mg 100 mg	4	The opiates and synthetic opiates (from 4 down to 10) are the most effective pain killers, but they are subject to the most abuse, and prescription pain killer addiction. All the opiates and derivatives are habit-forming. The inclusion of high amounts of acetaminophen with all these medications is a rather CRUEL attempt by the pharmaceutical companies to prevent abuse, since overdosing will result in the destruction of the liver. I would describe this, at best, as "not very nice". The Puritanical ethic at work, destroying livers, and lives. "Let's kill off all the druggies." This is way beyond cynical. Knowing that these drugs are abused, and then filling them up with the poisonous acetaminophen, is criminal malfeasance by the drug companies. One more reason to prosecute them. Fed Seeks Less Acetaminophen in Combo Pain Pills - Jan. 13, 2011 FINALLY! ** The score for Norco is an estimate. It did not exist at the time of the study.
Lorcet	hydrocodone and acetaminophen	5-500 mg	5
Vicodin	hydrocodone and acetaminophen	5-500 mg	5
Lorcet Plus	hydrocodone and acetaminophen	7.5-650 mg	5.5
Vicodin ES	hydrocodone and acetaminophen	7.5-750 mg	6
Norco	hydrocodone-APAP, and acetaminophen	5-325 mg 7.5-325 mg 10-325 mg	6.5**
Lortab	hydrocodone and acetaminophen	10-500 mg	7
Vicodin HP	hydrocodone and acetaminophen	10-660 mg	7
Percocet	oxycodone HCl with acetaminophen	2.5-325 mg 5- 325 mg 7.5-325 mg 7.5-500 mg 10-325 mg 10-650 mg	7	Oxycodone is very effective. ** The score for oxycodone is an estimate. It did not exist at the time of the study.
Percodan	oxycodone HCl, oxycodone terephthalate, and aspirin	4.50 mg 0.38 mg 325 mg	7
Oxycontin 40	oxycodone HCl	40 mg	8.5
RMS MS Contin	morphine sulfate	15 mg 30 mg 60 mg 100 mg	9	Morphine may be the THIRD strongest pain relief medicine available.
Duragesic Fentora Actiq	fentanyl	Skin patch Lollipop	10	** The score for fentanyl is an estimate. It did not exist at the time of the study. Fentanyl is very effective for gunshot wounds, and fragmentation wounds. However, there have been serious problems with fentanyl dosing (overdosing). Death has resulted from simply handling the medication with the fingers. One must use great care when handling fentanyl.
Dilaudid (tabs) Palladone (caps)	hydromorphone hydrochloride AKA dihydromorphinone	1 mg 2 mg 3 mg 4 mg	11 (was 9)	I recently received a very thoughtful email from a Special Operations medic. He stated that he has extensively administered all of these top medications. He concludes that Dilaudid is several times more effective than morphine, and that it has fewer side effects, although just as serious. I have therefore moved Dilaudid to the "most-effective drug" position on the list.
Opana Opana ER	oxymorphone extended release	5 mg 10 mg 5 mg 7.5 mg 10 mg 15 mg 20 mg 30 mg 40 mg	?	3 hours (also, injection and suppository) 5 - 8 hours