The danger the drug poses depends on the organ function of the individual patient before commencement of the medication. Its mechanism of action in improving sickle cell is not clear but it clearly helps. The drug is known to be cytotoxic, which means it destroys cells, the way cancer chemotherapy destroys bad cancer cells and affects some normal ones too. However, it seems like the cytotoxity of the drug actually helps in carrying out its function.

It is cytotoxic to some precursor cells in the bone marrow, so the assumption is that because it kills those cells, the bone marrow is forced to produce fetal hemoglobin. Let it be mentioned here that normal hemoglobin is “A”, abnormal is ‘S”, which is what is common in Sickle cell individuals. There are some other ones like Fetal hemoglobin which is “F”. This retains oxygen more, hence, helping people living with Sickle cell.

So the theory is that as Hydroxyurea destroys precursor cells, the bone marrow is forced to produce fetal hemoglobin, which is beneficial in HBSS patients. This like every theory in the world is just a guess until it is proven to be a fact.

Like every other drug, it has its side effects. Some of the more common symptoms are cough or hoarseness, fever or chills, lower back or side pain, painful or difficult urination. Less common symptoms are black, tarry stools, blackening of the fingernails and toenails, blood in the urine or stools, pinpoint red spots on the skin, sores in the mouth and on the lips, unusual bleeding or bruising (leg ulcers will not heal). Rare symptoms are confusion, convulsions (seizures), difficulty with urination, dizziness, headache, joint pain, seeing, hearing, or feeling things that are not there, swelling of the feet or lower legs, bleeding under the skin, blisters on the skin, bluish or pale color on the skin of the fingers or toes, coldness of the fingers or toes, crater-like lesions on the skin,
itching skin, numbness or tingling of the fingers or toes, pain in the fingers or toes,  unusual tiredness or weakness, weight loss.

Please note that not every patient that is administered this drug has side effects. Before taking this drug, visit an hematologist for investigations and tests to ensure you are eligible. You must also constantly visit your hematologist for tests while on the drug, to ensure you should continue taking it.Every organ must function properly before and while on the drug, as SCD might already compromise the functionality of some organs, hence taking the drug might worsen it. Pregnant women and women planning to have babies should also stay away from the drug.

One needs to be very careful of overdosing on the drug. If symptoms of overdose occur while taking Hydroxyurea, get emergency help immediately. Symptoms of overdose are scaling of the skin on the hands and feet, severe darkening of skin color, soreness, sores in the mouth and on the lips, swelling of the palms and soles of the feet, violet flushing of the skin.Some of the side effects that can occur with Hydroxyurea may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your hematologist may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your hematologist.