5. Hormone-altering drugs

Why they're prescribed: Hormone-altering drugs are used to treat a variety of conditions. Estrogen (Premarin), for example, is typically prescribed for hot flashes and other postmenopausal symptoms .

How they can cause depression: Manipulating hormone levels in the body can cause a variety of problems, particularly as medications interact with the central nervous system. Studies show that changes in hormonal levels are significantly associated with the appearance of symptoms of depression.

Alternatives: Once again, it's important to try to identify the cause of the symptoms. Review the medications you're taking — prescription and over the counter — with your doctor to identify some problems that can be corrected without additional drugs.

6. Stimulants

Why they're prescribed: Stimulant medications, such as methylphenidate (Ritalin) and modafinil (Provigil), are often prescribed to treat excessive daytime sleepiness, whether caused by hypersomnia, narcolepsy or sleep apnea. They're also prescribed for ADHD and fatigue.

How they can cause depression: Stimulant medications increase the level of dopamine in the body. Researchers believe that prolonged exposure to higher levels of dopamine may cause depression.

Alternatives: As with insomnia (see benzodiazepine hypnotics, above), it's important to identify the cause of excessive daytime sleepiness. Other medications you're taking — whether prescription or over the counter — could be responsible. Drugs with sedating effects, for example, are among the most common causes of excessive daytime sleepiness. (These include alpha- and beta-blockers, anti-diarrheal agents, antihistamines, antipsychotics, antispasmodics, cough suppressants, epilepsy drugs, skeletal muscle relaxants, Parkinson's drugs and some antidepressant medications.)

Nondrug causes of excessive daytime sleepiness include sleep deprivation, obstructive sleep apnea (when the throat muscles intermittently relax and block the airway during sleep) and depression. When such underlying conditions are treated appropriately, there's rarely, if ever, any need for the use of stimulants.

7. Anticonvulsants

Why they're prescribed: Anticonvulsant drugs, which have long been used to treat seizures, are increasingly being used to treat other medical conditions, including neuropathic pain, bipolar disorder, mood disorders and mania. Examples: carbamazepine (Tegretol), gabapentin (Neurontin), lamotrigine (Lamictal), pregabalin (Lyrica) and topiramate (Topamax).

How they can cause depression: Anticonvulsants are believed to work by affecting neurotransmitters, which act as chemical messengers in the brain. They may, for example, limit seizures from spreading by blocking the flow of signals from the central nervous system (CNS) rather than raise the threshold for seizures. All CNS depressants, including anticonvulsants, can cause depression.

Alternatives: For seizures, phenytoin (Dilantin), which raises the seizure threshold; for chronic neuropathic pain, venlafaxine (Effexor), which affects the two neurotransmitters, serotonin and norepinephrine, that are thought to play roles in regulating pain.

Next: H2 blockers, statins, and anticholinergic drugs. »