Most drugs have side effects of some sort, typically minor things like drowsiness or mood swings. But certain medications can also be the culprit of various other strange effects, like odd dreams or hallucinations — or even colored urine.

Of course, severe side effects are quite rare, and happen to only a handful of people. But side effects can be exacerbated if prescription drugs are mixed with other drugs or alcohol, so be sure to read about your medication before taking it. Below are six of some of the strangest side effects prescription drugs are often responsible for.

Vision Problems

Seeing spots or experiencing blind spots, blurred vision, or sensitivity to light can all be caused by different medications — particularly antihistamines, high blood pressure meds, or drugs that treat malaria or tuberculosis. Viagra, which is used for erectile dysfunction, has been investigated by federal health officials after complaints that the medication caused blindness or sudden vision loss when the optic nerve’s blood flow was blocked. Viagra has also been found to occasionally cause blue vision, or difficulties distinguishing between blue and green. Another drug associated with eye problems is Vasotec, which treats high blood pressure and congestive heart failure.

50 Shades Of Urine

If you’ve ever peed blue because of a drug, you’re aware of the strange things our body can produce. Plenty of prescription drugs can make you produce different shades of urine, such as Flagyl and furazolidone, which can make you pee black (perhaps the weirdest urine color of all). Other drugs, like Dyrenium, which is a diuretic that treats fluid retention and high blood pressure, can turn your pee blue; and Elavil, which is an antidepressant but is also used to regulate children who wet their beds, can turn your urine green.

While rainbow-colored urine may seem cool at first, it could be a sign that there’s something wrong with your body, like severe dehydration or internal bleeding. Be sure to ask your doctor if your drug may cause colored urine, or else make sure you’re not dehydrated, have a liver problem, or have internal bleeding. To find more information about the different colors drugs may induce, click here.

Moods Swings, Gambling Addictions, And Compulsive Behavior

One of the strangest things some prescription drugs can do is alter your behavior or impulse control. Mirapex in particular, which treats Parkinson’s disease and Restless Legs Syndrome (RLS), has been linked to “increased sexual urges, unusual urges to gamble, or other intense urges,” according to Drugs.com. Mirapex can also cause the patient to fall asleep suddenly, which is pretty weird. Mirapex increases the production of dopamine in the brain, because people with Parkinson’s often have low levels of dopamine. Dopamine aids in regulating the basal ganglia and movement in the body. In the past, patients taking Mirapex have claimed it led them to alcoholism, shopping addictions, and gambling addictions. While seemingly improbable and bizarre, these side effects are real for some and certain patients have won lawsuits against its creators, Pfizer and Boehringer Ingelheim, after claiming that the drug lost them thousands of dollars in gambling.

Hallucinations

Aside from psychedelic drugs like LSD or mushrooms, prescription drugs can cause hallucinations, too. In addition to addictive habits, Mirapex has been linked to hallucinations, or seeing images that aren’t really there. Some Parkinson’s patients on Mirapex report seeing strange things like snakes or people hiding in their closets (which frankly sounds terrifying). Lariam, in addition, which is used for malaria, has caused some patients to exhibit severe psychosis and hallucinatory behavior.

Blacking Out

Used to treat insomnia, the hypnotic Ambien will make you relaxed and drowsy with the aim of helping you sleep. But various reports have shown that Ambien can also wreak havoc on your sleep life and behaviors, even causing you to sleep walk.

Ambien was approved by the FDA in 1992 and quickly rose to become one of the top sleep aids, even though its prescribing information warned of sleep walking, sleep eating, “abnormal thinking,” and “strange behavior.” Since then, Ambien has been the cause of many strange occurrences, including Patrick Kennedy’s car accident in 2006, which he claimed to be because of an “Ambien blackout” during which he remembered nothing. “Ambien zombies” became a term to describe people who began sleep eating strange things like cigarettes and eggshells. According to the Ambien medication guide, “After taking AMBIEN, you may get up out of bed while not being fully awake and do an activity that you do not know you are doing. The next morning, you may not remember that you did anything during the night.” Some people have become addicted to the drug, describing its “high” as relaxed and surreal; but they’ve only been left with gaps in their memory and many blackout nights that could have put them or others on the verge of harm.

Vanishing Fingerprints

Though rare, it is a slight possibility that fingerprints might vanish through the use of the cancer drug capecitabine, which is also known as Xeloda. This was first discovered when a Singapore man was detained when entering the U.S. because of his lack of fingerprints — all because he was using the drug. Several other cancer patients had reported the loss of fingerprints individually, according to Dr. Eng-Huat Tan, a senior consultant in medical oncology at the National Cancer Centre in Singapore, who studied the drug’s effects. Capecitabine can cause a side effect known as hand-foot syndrome, which involves chronic inflammation of palms or soles, leading to the peeling of skin off these surfaces, and ultimately develop ulcers or blister — and lose fingerprints.