Chloroquine is a prescription medication designed to prevent malaria infection and treat existing cases. It has proven to be a very effective as an antimalarial, but the risk of side effects is relatively high compared with similar medications. A patient may experience chloroquine side effects such as nausea, cramping, and vomiting within a few hours of starting a course of the drug. Severe side effects that may involve vision loss, airway constriction, and fainting are less common but could become life threatening without prompt medical care.
Doctors are not entirely sure how chloroquine works in the body, which makes it difficult to predict the likelihood and type of side effects that may occur. The most common chloroquine side effects reported by patients taking the drug to prevent malaria include stomach upset, abdominal cramps, diarrhea, nausea, and vomiting. Some people experience headaches, dizzy spells and sleeping difficulties. Mildly itchy skin rashes that resemble psoriasis may also develop.
When chloroquine is taken to treat an active malaria infection, a patient might experience gastrointestinal side effects. In addition, vision changes are fairly common chloroquine side effects when it used as an active treatment agent. A person may have progressively dimming sight or see spontaneous flashes of bright yellow and red. The eyes can become very sensitive to sunlight and have trouble focusing on nearby objects. Rarely, total vision loss occurs that may or may not be reversible. Vision problems may be accompanied with hearing loss, vertigo, and facial spasms.
Allergic reactions to chloroquine are rare, but complications can be serious. Within hours and sometimes minutes of taking a dose, an allergic person can experience a widespread skin rash that causes painful, burning, itchy hives to erupt. The airways can become constricted to the point that breathing and swallowing become very difficult. If the brain is affected, confusion, muscle spasms, and seizures can occur.
A patient who experiences mild chloroquine side effects should keep taking the medication as directed and schedule an appointment with his or her doctor. A physician can perform a series of blood and imaging tests to check for possible kidney or liver damage, and then consider treatment options. In most cases, a patient can simply stop taking the drug and start a course of similar malaria medication to end the uncomfortable chloroquine side effects. Emergency room treatment should be sought in the case of an overdose, allergic reaction, or severe vision changes so doctors can provide intravenous fluids and anti-inflammatory drugs. Diuretics such as ammonium chloride may be given to help cleanse the body of chloroquine.