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Siklos (Hydroxyurea)

Prescription medicineOnly Available By Prescription

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What if I find a lower price with another pharmacy?

We guarantee the lowest price on all of our prescription products. If you find your medications cheaper at any other recognized licensed mail order pharmacy, we will not only match their price, we will beat it by 25% of the difference. It is our 125% price match guarantee!

Example: If you find a product on Canada Drugs Direct for $50.00 and find the same product for $40.00 at another mail order pharmacy, we will provide you with a $12.50 discount, bringing your total to $37.50.

To get the discount please make sure to mention the price match to the customer service team when they call to collect payment for your order. Or call toll free at 1-888-904-8467 to place the order through the phone.

Terms & Conditions of Program

  • Guaranteed lowest price is only valid at the time of sale.
  • We will only match the current advertised price.
  • Products must be identical and in stock at the time of placing an order with a licensed mail order pharmacy. The must be a member of CIPA (Canadian International Pharmacy Association).
  • Products must be authentic in brand and size (same manufacturer, same country of manufacture, same pack size, same strength and same quantity).
  • Products must be new. We cannot match the price of any used, short expiry or expired product.
  • Price match can only be issued over the phone with our customer service team
What is a Generic Drug?

A generic drug is a copy of the brand-name drug with the same dosage, safety, strength, quality, consumption method, performance, and intended use. Before generics become available on the market, the generic company must prove it has the same active ingredients as the brand-name drug and works in the same way and in the same amount of time in the body.

The only differences between generics and their brand-name counterparts is that generics are less expensive and may look slightly different (eg. different shape or color), as trademarks laws prevent a generic from looking exactly like the brand-name drug.

Generics are less expensive because generic manufacturers don't have to invest large sums of money to develop a drug. When the brand-name patent expires, generic companies can manufacture a copy of the brand-name and sell it at a substantial discount.


Your doctor may prescribe Siklos to treat painful crises in patients with sickle cell anemia. Sickle cell anemia is a disease where red blood cells are not shaped correctly, and this can cause many symptoms. 

Fact Table







Legal status


Chemical Name


Elimination half-life

2–4 hours

Dosage (Strength)



Consult Doctor



Protein binding

More than 76%

PubChem CID






ATC code






Routes of administration

By mouth


Siklos should be taken exactly as prescribed by the healthcare provider. It should be dosed by a specialist and only changed as directed.

The starting dosage is 20 mg per kilogram of body weight. The dose may be increased to a max of 35 mg per kilogram of body weight.

Siklos is available in 100 mg and 1000 mg tablets.


The active ingredient in Siklos is hydroxyurea.


Siklos can interact with the following medications:

  • Abrocitinib
  • Baricitnib
  • BCG (Intravesical)
  • Cladribine
  • Dengue tetravalent vaccine
  • Didanosine
  • Dipyrone
  • Fexinidazole
  • Natalizumab
  • Pimecrolimus
  • Poliovirus vaccine
  • Rubella vaccine
  • Ruxolitinib
  • Stavudine
  • Tacrolimus
  • Talimogene
  • Tertomotide
  • Tofacitinib
  • Typhoid vaccine
  • Upadacitinib
  • Varicella vaccine
  • Yellow fever vaccine

Tell your doctor if you are taking any of the above drugs before starting Siklos.


Siklos should not be used if you are pregnant or planning to become pregnant. Use appropriate and effective contraception methods while taking this drug.

You may need to stop this drug if leg ulcers or other skin reactions occur.

Use caution if you are taking other antiviral medications.

Do not receive live vaccines while taking this drug.

Side Effects

Common side effects of Siklos treatment may include:

  • Acute mucocutaneous toxicity
  • Alopecia
  • Anemia
  • Arthralgia
  • Asthenia
  • Asthma
  • Back pain
  • Bacterial infection
  • Bone marrow depression
  • Bronchitis
  • Constipation
  • Cough
  • Dermal ulcer
  • Dermatological reaction
  • Diarrhea
  • Disorder of urinary system
  • Dizziness
  • Dyspnea
  • Eczema
  • Fatigue
  • Fever
  • Headache
  • Hemorrhage
  • Influenza
  • Leg ulcer
  • Leukopenia
  • Limb pain
  • Macrocytosis
  • Nasopharyngitis
  • Nausea
  • Neutropenia
  • Peripheral edema
  • Pulmonary disease
  • Renal disease
  • Severe nervous system disease
  • Skin depigmentation
  • Thrombocytopenia
  • Upper abdominal pain
  • Urinary tract infection
  • Viral infection
  • Vitamin D deficiency
  • Weight gain
  • Xeroderma


Siklos. Bryn Mawr, PA: Medunik USA, Inc; 2017.

IMPORTANT NOTE: The above information is intended to increase awareness of health information and does not suggest treatment or diagnosis. This information is not a substitute for individual medical attention and should not be construed to indicate that use of the drug is safe, appropriate, or effective for you. See your health care professional for medical advice and treatment.

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