5 Unexpected Side Effects of Common Medications

Some popular drugs may spark odd, unexpected reactions, like color blindness, deja vu and even compulsive gambling

By Linda Melone
Originally Posted On September 18, 2013


Even the most-studied, widely prescribed drugs can have unwanted side effects, like stomach upset, drowsiness and fatigue. It's the price we pay to address more serious medical issues. Some medications, though, can cause unexpected and unusual side effects very different than those listed at the top of the box or pamphlet, says pharmacist Suzy Cohen, author of Drug Muggers: What Medications Are Robbing Your Body of Essential Nutrients and How to Restore Them.

Below, we list some of these unexpected side effects and suggest alternatives for those who might experience them. They are generally rare and non-life-threatening, but speak to your doctor or pharmacist and read consumer advisories for all your prescriptions to learn more.

Drug: Lorazepam
Unexpected side effect: déjà vu
Fewer than 5 percent of people who take this anti-anxiety medication or others in the class of drugs known as benzodiazepines — like Xanax, Librium, Tranxene and Valium— will experience this odd effect, Cohen says.

This form of déjà vu, however, is not exactly what you'd expect. "It's not the feeling that you've done this before or been here before," Cohen says. "It's more like a feeling that is hard to put your finger on, like a flashback to a certain time or place. Maybe you suddenly imagine or dream you are back in your childhood, for example." (This effect has also been linked, in rare cases, to the antiviral medication amantadine.)

The cause is unclear. "Epilepsy, anxiety and other psychiatric disorders are associated with déjà vu," Cochrane says, "suggesting that this effect may sometimes be a symptom of an underlying disease rather than a drug side effect." Taking lorazepam in conjunction with drugs that affect neurotransmitters such as dopamine may bring on or intensify the effect.
If you experience déjà vu, talk to your doctor about switching to a different class of anti-anxiety drugs or consider natural anti-anxiety herbs, like Valerian root, passionflower, hops or glycine powder.
Drug: Viagra
Unexpected side effect: color blindness
Its commercials are so widely aired that many of us may be able to recite the popular erectile-dysfunction drug's most common side effects by heart. But most users are unaware that in rare cases, it can also cause a type of color blindness, usually involving a difficulty distinguishing blue and green. The effect is usually temporary, although in isolated incidents, the drug has caused brief or long-term total vision loss. The effect appears to be caused by an interruption of blood flow to the optic nerve.

If you experience this effect, you should look into one of several natural treatments for improved sexual function, including yohimbe, maca root and ginseng. "Viagra and similar drugs are just short-term fixes," Cohen says. "They do nothing for the underlying cause, which is usually testosterone deficiency." If you discover that you or your partner has testosterone deficiency, she says, "Drug therapy such as testosterone replacement would be ideal in terms of a long-term solution."

Drug: Dapsone
Unexpected side effect: carbon monoxide poisoning symptoms

This antibiotic is often taken by people with compromised immune systems – including HIV patients and those with leprosy or skin conditions – to prevent infections. But 1 to 5 percent of users may experience a scary and disturbing disorder known as acquired methemoglobinemia, which involves breathing difficulty, cyanosis (gray or blue skin), abnormal heart rhythm, chest pain and weakness. These symptoms are typical of carbon-monoxide poisoning. The big difference: There's no carbon monoxide involved and the effect is not life-threatening. 

In methemoglobinemia, Cohen explains, red blood cells contain methemoglobin (a form of hemoglobin) at levels higher than 1 percent. This elevated level of methemoglobin can prevent hemoglobin from releasing oxygen effectively to body tissues. Severe episodes may require treatment, including a blood transfusion. But in most cases of acquired methemoglobinemia, no action needs to be taken, except to cease using the drug, according to the National Institutes of Health. Alternative medications include Bactrim DS or Mepron, which have a lower risk of this rare condition.