The Ten Scariest Side Effects of Prescription Drugs

Each year, about 4,5 million Americans visit a doctor's office or emergency room due to drug-related side effects. Pharmacy Time tells about the 10 most terrible side effects of prescription drugs.

Adverse drug reactions are side effects that have significant clinical and economic costs. They can lead to increased emergency department visits and prolonged hospital stays.

It can be difficult to pinpoint a reaction to one particular medicine. The Food and Drug Administration (FDA) requires drug manufacturers to list all side effects effects in the labeling of their products, which have been registered in clinical studies.

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Below is a list of 10 harmful and potentially fatal side effects of commonly prescribed medications.

1. Hallucinations

Hallucinations are the sensation of something that is not really there. Types of hallucinations include visual, auditory, olfactory, tactile, gustatory, and general somatic.

Hallucinations are a common symptom of schizophrenia. They can be caused by excessive alcohol use, drug abuse, depression, lack of sleep, dementia, or certain prescription medications.

Psychiatric medications such as olanzapine (Zyprexa), quetiapine (Seroquel), and haloperidol (Haldol) can cause hallucinations. Hallucinations have also been reported with zolpidem (Ambien), eszopiclone (Lunesta), clonazepam (Klonopin), lorazepam (Ativan), ropinirole (Requip), and some anticonvulsants.

Cephalosporins and sulfa drugs (two common classes of antibiotics) have been associated with hallucinations in rare cases.

2. Memory loss

While memory loss is a natural part of aging, it can also be a side effect of certain medications.

The most notable class of drugs that can cause memory loss are the nonbenzodiazepine sedative-hypnotics. These include Ambien, Lunesta, and Sonata. These drugs can sometimes cause amnesia and potentially dangerous behavior, such as cooking, having sex, or driving without remembering the event.

Medications that can cause memory loss include benzodiazepines, statins, some anticonvulsants, opioids, and incontinence medications.

3. Priapism

Priapism is an unwanted, painful, persistent erection that is not caused by sexual stimulation or arousal. If left untreated, tissue damage can occur, resulting in the inability to have or maintain an erection.

Causes of priapism include certain medical conditions, injuries, alcohol use, and prescription drug use. Medications that cause priapism include trazodone (Desyrel), clozapine (Clozaril), hydroxyzine (Atarax), chlorpromazine (Thorazine), prazosin (Minipress), warfarin (Coumadin), testosterone therapy, and serotonin reuptake inhibitors such as sertraline (Zoloft), fluoxetine (Prozac), and paroxetine (Paxil).

4. Blood clots

Blood clots form in the body under many normal circumstances in response to injury. However, some prescription drugs also contribute to the formation of blood clots. If left untreated, blood clots can break away from their original source and travel to other parts of the body, sometimes becoming fatal.

Female oral contraceptives and hormone replacement therapy drugs carry an increased risk of blood clots. In addition, all testosterone replacement drugs carry the same risk of blood clots.

5. Compulsive behavior

Compulsive behavior involves repeatedly performing an action without control, which interferes with a person's life.

Requip and pramipexole (Mirapex), dopamine agonists, are indicated for Parkinson's disease and restless legs syndrome. The drugs may cause problems with impulse control or compulsive behavior.

According to the drug package inserts, "case reports suggest that patients may experience gambling, increased sexual desire, urge to spend money, overeating and/or other strong urges, and an inability to control these urges."

More recently, the antipsychotic drug aripiprazole (Abilify) has been linked to compulsive behavior side effects – compulsive gambling – in some patients.

6. Stevens-Johnson syndrome

Stevens-Johnson syndrome (SJS) is a rare, life-threatening hypersensitivity reaction of the skin and mucous membranes. During SJS, large patches spread rapidly and join together. This leads to blistering, necrosis, and peeling of the skin.

Lamotrigine (Lamictal) causes a relatively high incidence of SJS, especially when given in high doses. The FDA has required a black box warning on the package to inform consumers of this risk. Other drugs that may cause SJS include allopurinol (Zyloprim), acetaminophen (Tylenol), ibuprofen (Motrin), naproxen (Aleve), sulfa drugs, penicillin, barbiturates, and other anticonvulsants.

7. Birth defects

A birth defect occurs when a baby develops inside its mother's body. An estimated 1 in 33 babies in the United States is born with a birth defect.

Thalidomide is one of the oldest and best-known teratogenic drugs. In 1954, thousands of women took it. The drug was then touted as a miracle cure for insomnia, coughs, colds, and headaches. It led to the deaths of about 2000 babies and serious birth defects in more than 10 children.

Known teratogenic prescription drugs include warfarin, divalproex (Depakote), Paxil, topiramate (Topamax), methotrexate (Rheumatrex), angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, nonsteroidal anti-inflammatory drugs, oral contraceptives, statins, and tetracyclines.

Although the risk of birth defects is highest during the first trimester, women should talk with their doctors about the risks and benefits of all medications at any stage of pregnancy.

8. Cancer

Tamoxifen (Nolvadex), which is used to treat breast cancer, increases the risk of uterine cancer. In response, the FDA required the manufacturer to add a black-box warning to inform consumers of the risk.

The labeling of the type 2 diabetes drug pioglitazone (Actos) includes a warning about an increased risk of bladder cancer.

All glucagon-like peptide-1 receptor agonists carry a black box warning about the risk of thyroid C-cell tumors, which have been observed in rats and mice.

Animal studies have shown that metronidazole (Flagyl) is a carcinogen.

9. Suicidal tendencies

This issue dates back to 1990. Paxil was reported to cause suicide in patients. Today, all antidepressants carry a black box warning on the label about the increased risk of suicidal thoughts and behavior in children, adolescents, and young adults with major depressive disorder and other mental health conditions.

Current clinical evidence on this topic is inconclusive. Some studies have shown that antidepressant use is associated with an increased risk of suicidal behavior, while other studies have shown no increased risk.

Other medications that may be associated with suicidal thoughts and behavior include montelukast (Singulair), isotretinoin (Claravis), varenicline (Chantix), and mefloquine (Lariam).

10. Death

Sudden death from heart failure is the leading cause of natural death in the United States, killing an estimated 325 adults each year.

A number of antipsychotic drugs, such as Seroquel, Zyprexa, and risperidone (Risperdal), have been linked to such sudden death. Increased incidence was seen in older people and those taking other heart medications in combination.

Antiarrhythmic drugs that have labeled sudden death from heart failure include sotalol (Betapace), amiodarone (Cordarone), and procainamide (Procanbid).

Finally, the labeling for morphine and Adderall includes warnings about an increased risk of sudden death due to cardiac abnormalities.