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Hydroxychloroquine – Curious Effects on Very Different Parts of the Body

Almost certainly you have not heard of hydroxychloroquine: it is a rather unpopular drug. However, it has curious effects on very different parts of the body.

Hydroxychloroquine is a drug little known for the relatively few utilities it has . However, we find that their uses, although few, are diverse. Next, we will explain what its indications are (situations in which its use is recommended) and its adverse effects. We will complete the entry, in addition, with its contraindications (situations in which it should not be used).



The  Plasmodium (microorganism that causes malaria) has several stages of reproduction. One of them consists of its introduction in red blood cells( blood cells that transport oxygen). Once inside, they feed on a part of hemoglobin (the concrete molecule that carries oxygen), subjecting it to various reactions.

The role of hydroxychloroquine is to prevent  Plasmodium from digesting hemoglobin. It succeeds because this microorganism needs a low pH to carry out these reactions. Hydroxychloroquine increases this pH so that digestion is not possible.

Rheumatoid arthritis

The rheumatoid arthritis (RA) is an autoimmune inflammatory disease. This means that the immune cells (and various systems of immunity) of the organism itself recognize as foreign certain molecules of their own. Thus, it develops against them an inflammatory reaction, in this case in the joints.

Hydroxychloroquine is beneficial in these cases because it prevents some immune cells from being transported to the joints . In addition, they prevent the binding of certain immune complexes with the own molecules recognized as foreign.

Gout-Rheumatoid Arthritis

Lupus is also an autoimmune disease. Thus, the benefits of hydroxychloroquine in this case are similar to those experienced in rheumatoid arthritis.

Side effects


Hydroxychloroquine produces undesirable effects both at the level of the cornea and at the level of the retina . The first corresponds to the hard layer that covers the eye. The second is the innermost layer thanks to which we can perceive images. The damages produced can be symptomatic or asymptomatic.

The symptoms that can occur at the level of the retina are scotomas (black spots in the visual field) or difficulty in low-light vision (nictalopia) . They are usually reversible, although in some cases the lesion is irreversible.

As for the cornea, edema (swelling) and opacities may occur. This can trigger blurred vision , photophobia (incident light hurts) or decreased visual acuity.

child with vision problems


In this regard , nausea, vomiting, diarrhea and abdominal pain may occur All this can lead to anorexia (lack of appetite), with the possible associated weight decrease.


Throughout the use of hydrochloroquine the appearance of myopathies and neuromyopathies (pathologies of the muscles and of the set of muscles and nerves) has been described. This includes, among others, the appearance of muscle weakness. Myopathy may be reversible, but it may take several months until normalcy returns.

This is why periodic reviews of muscle strength are necessary, as well as explorations of the osteotendinous reflexes (the most popular is the patellar).


Hydroxychloroquine should be avoided in patients under the following circumstances:

  • Alterations in visual acuity or visual field (may be accentuated)
  • Hypersensitivity (allergy) to compounds derived from 4-aminoquinoline (this drug is a derivative of that compound).

In addition, there are situations that must be taken into account although they do not constitute contraindications as such: these are precautions. It is necessary, first of all, to carry out a close surveillance if the patient has poor renal or hepatic function, because these two organs are responsible for metabolizing and expelling it from the body.

Close monitoring is also necessary in patients with cutaneous pathologies (such as psoriasis ). This is because hydroxychloroquine has a special avidity for the skin and could increase its damage. For this reason it could develop hypersensitivity reactions.

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