The 50 most dangerous drugs

While overdose deaths from prescription opioids have nearly quadrupled since 1999, some of the most dangerous drugs don't require a prescription.

Using data from the Food and Drug Administration for 2004 through 2015, HealthGrove looked at the 150 drugs that are involved in the highest number of adverse reactions and ranked them by the percent of these reactions classified as serious. For many of these reactions, the FDA database uses medical terminology, such as pyrexia and dyspnoea for fever and labored breathing, respectively.

Read more: Common allergy medications could damage brain, increase risk of dementia

Some of the most dangerous drugs don’t require a prescription

The top 50 drugs with the most serious adverse reactions are considered the most dangerous. Though most on the list require a prescription and treat serious diseases, those like Advil and acetaminophen don't.

It’s important to note that these medicines may not be inherently dangerous, but improper dosage, combining medicines or taking them with substances like alcohol can dramatically increase risk.

One-third of Americans say they "combine medications when treating multiple symptoms," according to the National Council on Patient Information, cited in a New York Times report on over-the-counter medicines. The same source also claims that only one in ten people read the labels entirely and one in five admits to using medication more than the label indicates. This creates an environment primed for unintended drug interactions and overdoses.

Read more: 5 serious health risks of drinking diet soda

Additionally, people over 65 years old — those most likely to take multiple drugs for chronic health issues — account for approximately 40 percent of over-the-counter drug usage. This puts this group at greater risk for trouble with these drugs by way of adverse side effects and interactions.

Despite the potential for negative consequences of drug use and misuse, modern pharmaceuticals have greatly contributed to the health and longevity of people around the world. Though many are regarded as safe, as more drugs become available over the counter and prescriptions of others rise, consumer awareness becomes increasingly important.

Note: In the case of ties, the drug with the highest number of total reported reactions is ranked higher.

#50. Losartan

Percent of Reactions That Were Serious: 70%
Number of Serious Reactions: 24,242
Total Number of Reported Reactions: 34,571
Therapeutic Class: Cardiovascular Agent
Brand Names: Cozaar

#49. Alprazolam

Percent of Reactions That Were Serious: 70%
Number of Serious Reactions: 51,950
Total Number of Reported Reactions: 73,606
Therapeutic Class: Antianxiety
Brand Names: Gabazolamine-0.5, Niravam, Xanax, Xanax Xr, Alti-Alprazolam

#48. Tramadol

Percent of Reactions That Were Serious: 71%
Number of Serious Reactions: 26,278
Total Number of Reported Reactions: 36,867
Therapeutic Class: Analgesic
Brand Names: Conzip, Fusepaq Synapryn, Rybix Odt, Ryzolt, Ultram, Ultram Er

#47. Venlafaxine

Percent of Reactions That Were Serious: 71%
Number of Serious Reactions: 33,623
Total Number of Reported Reactions: 47,132
Therapeutic Class: Antidepressant
Brand Names: Effexor, Effexor-Xr

#46. Sertraline

Percent of Reactions That Were Serious: 71%
Number of Serious Reactions: 45,622
Total Number of Reported Reactions: 64,182
Therapeutic Class: Antidepressant
Brand Names: Zoloft

#45. Metoprolol

Percent of Reactions That Were Serious: 71%
Number of Serious Reactions: 71,979
Total Number of Reported Reactions: 100,829
Therapeutic Class: Cardiovascular Agent
Brand Names: Lopressor, Toprol Xl

#44. Aspirin

Percent of Reactions That Were Serious: 71%
Number of Serious Reactions: 134,402
Total Number of Reported Reactions: 187,836
Therapeutic Class: Analgesic
Brand Names: Ascriptin, Aspergum, Aspirtab, Bayer, Easprin, Ecotrin, Ecpirin, Entercote, Genacote, Halfprin, Ninoprin, Norwich Aspirin

#43. Atenolol

Percent of Reactions That Were Serious: 72%
Number of Serious Reactions: 45,374
Total Number of Reported Reactions: 62,930
Therapeutic Class: Cardiovascular Agent
Brand Names: Tenormin

#42. Prednisone

Percent of Reactions That Were Serious: 72%
Number of Serious Reactions: 60,187
Total Number of Reported Reactions: 83,321
Therapeutic Class: Endocrine-Metabolic Agent
Brand Names: Deltasone, Prednicot, Prednisone Intensol, Rayos, Sterapred, Sterapred Ds

#41. Fluoxetine

0

Percent of Reactions That Were Serious: 73%
Number of Serious Reactions: 36,722
Total Number of Reported Reactions: 50,213
Therapeutic Class: Antidepressant
Brand Names: Prozac, Prozac Weekly, Rapiflux, Sarafem, Selfemra, Phl-Fluoxetine

#40. Fentanyl

Percent of Reactions That Were Serious: 74%
Number of Serious Reactions: 29,996
Total Number of Reported Reactions: 40,444
Therapeutic Class: Analgesic
Brand Names: Abstral, Actiq, Fentora, Onsolis, Subsys

#39. Acetaminophen

Percent of Reactions That Were Serious: 74%
Number of Serious Reactions: 119,389
Total Number of Reported Reactions: 160,481
Therapeutic Class: Analgesic
Brand Names: Ofirmev

#38. Amlodipine

Percent of Reactions That Were Serious: 75%
Number of Serious Reactions: 95,694
Total Number of Reported Reactions: 126,505
Therapeutic Class: Cardiovascular Agent
Brand Names: Norvasc

#37. Cyclosporine

Percent of Reactions That Were Serious: 76%
Number of Serious Reactions: 24,422
Total Number of Reported Reactions: 31,881
Therapeutic Class: Immune Suppressant
Brand Names: Gengraf, Neoral, Sandimmune, Apo-Cyclosporine

#36. Risperidone

Percent of Reactions That Were Serious: 76%
Number of Serious Reactions: 34,023
Total Number of Reported Reactions: 44,415
Therapeutic Class: Antipsychotic
Brand Names: Risperdal, Risperdal M-Tab, Risperidone M-Tab

#35. Warfarin

Percent of Reactions That Were Serious: 76%
Number of Serious Reactions: 79,961
Total Number of Reported Reactions: 104,230
Therapeutic Class: Anticoagulant
Brand Names: Coumadin, Jantoven

#34. Lorazepam

Percent of Reactions That Were Serious: 77%
Number of Serious Reactions: 42,737
Total Number of Reported Reactions: 54,873
Therapeutic Class: Antianxiety
Brand Names: Ativan, Lorazepam Intensol

#33. Valsartan

Percent of Reactions That Were Serious: 77%
Number of Serious Reactions: 46,987
Total Number of Reported Reactions: 60,639
Therapeutic Class: Cardiovascular Agent
Brand Names: Diovan

#32. Pantoprazole

Percent of Reactions That Were Serious: 77%
Number of Serious Reactions: 48,736
Total Number of Reported Reactions: 62,968
Therapeutic Class: Gastric Acid Secretion Inhibitor
Brand Names: Protonix, Protonix Iv

#31. Oxycodone

Percent of Reactions That Were Serious: 77%
Number of Serious Reactions: 56,165
Total Number of Reported Reactions: 72,020
Therapeutic Class: Analgesic
Brand Names: Dazidox, Eth-Oxydose, Oxaydo, Oxycontin, Oxycontin Cr, Oxydose, Oxyfast, Oxy Ir, Roxicodone, Roxicodone Intensol, Apo-Oxycodone Cr, Co Oxycodone Cr, Oxycodone, Oxy-Ir, Oxyneo, Pms-Oxycodone

#30. Drospirenone And Ethinyl Estradiol

Percent of Reactions That Were Serious: 78%
Number of Serious Reactions: 31,921
Total Number of Reported Reactions: 40,426
Therapeutic Class: Monophasic Contraceptive Combination
Brand Names: Gianvi, Loryna, Nikki, Ocella, Syeda, Vestura, Yasmin, Yaz, Yaz 28, Zarah

#29. Citalopram

Percent of Reactions That Were Serious: 78%
Number of Serious Reactions: 42,147
Total Number of Reported Reactions: 53,752
Therapeutic Class: Antidepressant
Brand Names: Celexa

#28. Diclofenac

Percent of Reactions That Were Serious: 79%
Number of Serious Reactions: 27,921
Total Number of Reported Reactions: 35,286
Therapeutic Class: Central Nervous System Agent
Brand Names: Cambia, Cataflam, Voltaren, Voltaren-Xr, Zipsor, Zorvolex

#27. Conjugated Estrogens

Percent of Reactions That Were Serious: 79%
Number of Serious Reactions: 40,659
Total Number of Reported Reactions: 51,272
Therapeutic Class: Female Reproductive Agent
Brand Names: Premarin, Premarin Vaginal

#26. Olanzapine

Percent of Reactions That Were Serious: 80%
Number of Serious Reactions: 32,222
Total Number of Reported Reactions: 39,957
Therapeutic Class: Antipsychotic
Brand Names: Zyprexa, Zyprexa Zydis

#25. Diazepam

Percent of Reactions That Were Serious: 81%
Number of Serious Reactions: 31,794
Total Number of Reported Reactions: 38,978
Therapeutic Class: Anticonvulsant
Brand Names: Diastat, Diastat Pediatric

#24. Rivaroxaban

Percent of Reactions That Were Serious: 81%
Number of Serious Reactions: 33,317
Total Number of Reported Reactions: 41,114
Therapeutic Class: Anticoagulant
Brand Names: Xarelto

#23. Alendronate

Percent of Reactions That Were Serious: 82%
Number of Serious Reactions: 39,257
Total Number of Reported Reactions: 47,769
Therapeutic Class: Calcium Regulator
Brand Names: Fosamax

#22. Clopidogrel

Percent of Reactions That Were Serious: 82%
Number of Serious Reactions: 70,205
Total Number of Reported Reactions: 85,447
Therapeutic Class: Platelet Aggregation Inhibitor
Brand Names: Plavix

#21. Furosemide

Percent of Reactions That Were Serious: 82%
Number of Serious Reactions: 102,865
Total Number of Reported Reactions: 124,020
Therapeutic Class: Cardiovascular Agent
Brand Names: Furocot, Lasix

#20. Digoxin

Percent of Reactions That Were Serious: 83%
Number of Serious Reactions: 30,355
Total Number of Reported Reactions: 36,506
Therapeutic Class: Cardiovascular Agent
Brand Names: Digitek, Digox, Lanoxicaps, Lanoxin, Lanoxin Pediatric, Digitaline Nativelle

#19. Spironolactone

Percent of Reactions That Were Serious: 84%
Number of Serious Reactions: 28,871
Total Number of Reported Reactions: 34,336
Therapeutic Class: Cardiovascular Agent
Brand Names: Aldactone

#18. Allopurinol

3

Percent of Reactions That Were Serious: 84%
Number of Serious Reactions: 30,921
Total Number of Reported Reactions: 36,755
Therapeutic Class: Antigout
Brand Names: Aloprim

#17. Morphine

4

Percent of Reactions That Were Serious: 84%
Number of Serious Reactions: 37,986
Total Number of Reported Reactions: 44,906
Therapeutic Class: Analgesic
Brand Names: Avinza, Kadian, Kadian Er, Morphabond, Ms Contin, Msir, Oramorph Sr, Roxanol, Roxanol-T

#16. Ondansetron

5

Percent of Reactions That Were Serious: 85%
Number of Serious Reactions: 31,005
Total Number of Reported Reactions: 36,133
Therapeutic Class: Antiemetic
Brand Names: Zofran, Zofran Odt, Zuplenz

#15. Ramipril

6

Percent of Reactions That Were Serious: 85%
Number of Serious Reactions: 32,374
Total Number of Reported Reactions: 37,895
Therapeutic Class: Antihypertensive
Brand Names: Altace

#14. Rosiglitazone

7

Percent of Reactions That Were Serious: 85%
Number of Serious Reactions: 87,352
Total Number of Reported Reactions: 101,873
Therapeutic Class: Antidiabetic
Brand Names: Avandia

#13. Medroxyprogesterone

8

Percent of Reactions That Were Serious: 89%
Number of Serious Reactions: 34,018
Total Number of Reported Reactions: 38,079
Therapeutic Class: Endocrine-Metabolic Agent
Brand Names: Provera, Alti-Mpa

#12. Lenalidomide

9

Percent of Reactions That Were Serious: 89%
Number of Serious Reactions: 69,123
Total Number of Reported Reactions: 77,417
Therapeutic Class: Immune Modulator
Brand Names: Revlimid

#11. Methylprednisolone

0

Percent of Reactions That Were Serious: 90%
Number of Serious Reactions: 30,040
Total Number of Reported Reactions: 33,095
Therapeutic Class: Endocrine-Metabolic Agent
Brand Names: Medrol, Medrol Dosepak, Methylpred-Dp

#10. Metoclopramide

1

Percent of Reactions That Were Serious: 91%
Number of Serious Reactions: 32,757
Total Number of Reported Reactions: 35,623
Therapeutic Class: Antiemetic
Brand Names: Metozolv Odt, Reglan

#9. Infliximab

2

Percent of Reactions That Were Serious: 91%
Number of Serious Reactions: 68,167
Total Number of Reported Reactions: 74,738
Therapeutic Class: Immunological Agent
Brand Names: Remicade

#8. Tacrolimus

3

Percent of Reactions That Were Serious: 92%
Number of Serious Reactions: 27,964
Total Number of Reported Reactions: 30,262
Therapeutic Class: Antipsoriatic
Brand Names: Protopic

#7. Zoledronic Acid

4

Percent of Reactions That Were Serious: 93%
Number of Serious Reactions: 35,581
Total Number of Reported Reactions: 38,016
Therapeutic Class: Calcium Regulator
Brand Names: Reclast, Zometa

#6. Dexamethasone

5

Percent of Reactions That Were Serious: 93%
Number of Serious Reactions: 38,966
Total Number of Reported Reactions: 41,636
Therapeutic Class: Endocrine-Metabolic Agent
Brand Names: Baycadron Elixer, Decadron, Dekpak 13 Day Taperpak, Dexamethasone Intensol, Dexpak, Dexpak 10 Day Taperpak, Dexpak Jr, Zema-Pak

#5. Clozapine

6

Percent of Reactions That Were Serious: 95%
Number of Serious Reactions: 29,470
Total Number of Reported Reactions: 30,914
Therapeutic Class: Antipsychotic
Brand Names: Clozaril, Fazaclo, Versacloz

#4. Rituximab

7

Percent of Reactions That Were Serious: 96%
Number of Serious Reactions: 30,014
Total Number of Reported Reactions: 31,157
Therapeutic Class: Antineoplastic Agent
Brand Names: Rituxan

#3. Bevacizumab

8

Percent of Reactions That Were Serious: 96%
Number of Serious Reactions: 39,957
Total Number of Reported Reactions: 41,281
Therapeutic Class: Immunological Agent
Brand Names: Avastin

#2. Prednisolone

9

Percent of Reactions That Were Serious: 96%
Number of Serious Reactions: 42,323
Total Number of Reported Reactions: 43,817
Therapeutic Class: Endocrine-Metabolic Agent
Brand Names: Bubbli-Pred, Cotolone, Flo-Pred, Millipred, Millipred Dp, Orapred, Orapred Odt, Pediapred, Prelone, Veripred 20, Pms-Prednisolone

#1. Cyclophosphamide

0

Percent of Reactions That Were Serious: 97%
Number of Serious Reactions: 33,128
Total Number of Reported Reactions: 34,076
Therapeutic Class: Antineoplastic Agent
Brand Names: Cytoxan, Cytoxan Lyophilized

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