Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Galexos. If you are concerned about side effects, discuss the risks and benefits of Galexos with your doctor.

The following side effects have been reported by at least 1% of people taking Galexos. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• Constipation
• increased sensitivity to sunlight (Sunburn, blistering, redness)
• itchiness
• skin rash

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Galexos.

Each white capsule, marked with "TMC435 150" in black ink contains 154.4 mg of simeprevir sodium salt, which is equivalent to 150 mg of simeprevir. Nonmedicinal ingredients: colloidal anhydrous silica, croscarmellose sodium, lactose monohydrate, magnesium stearate and sodium lauryl sulphate; capsule: gelatin and titanium dioxide (E171); ink: iron oxide black (E172) and shellac (E904).

Do not take simeprevir if you:

• are allergic to simeprevir or any ingredients of the medication
• cannot take sofosbuvir, peginterferon alfa or ribavirin
• are pregnant or plan to become pregnant

There may be an interaction between simeprevir and any of the following:

• Abiraterone
• Aliskiren
• alpha blockers (e.g., Alfuzosin, Doxazosin, Silodosin, Tamsulosin)
• Amiodarone
• anticancer medications (e.g., Cabazitaxel, Docetaxel, Doxorubicin, Etoposide, Ifosfamide, Irinotecan, Vincristine)
• antipsychotics (e.g., Chlorpromazine, Clozapine, Haloperidol, Olanzapine, Quetiapine, Risperidone)
• Apixaban
• Aprepitant
• "azole" antifungals (e.g., itraconazole, ketoconazole, Voriconazole)
• barbiturates (e.g., butalbital, pentobarbital, Phenobarbital)
• benzodiazepines (e.g., Chlordiazepoxide, Clonazepam, Diazepam, Lorazepam)
• Bicalutamide
• Bosentan
• Bromocriptine
• Buprenorphine
• Buspirone
• Calcitriol
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• Carvedilol
• cetirizine
• chloroquine
• Cimetidine
• ciprofloxacin
• Cobicistat
• Colchicine
• conivaptan
• Cyclosporine
• dabigatran
• Dabrafenib
• Dantrolene
• Dapsone
• Deferasirox
• Desvenlafaxine
• Dexamethasone
• Digoxin
• Disopyramide
• Domperidone
• Dronedarone
• Edoxaban
• Eltrombopag
• Enzalutamide
• ergot-containing medications (e.g., Dihydroergotamine, ergotamine)
• estrogens (e.g., conjugated estrogen, Estradiol, ethinyl estradiol)
• Flutamide
• Gemfibrozil
• "gliptin" Diabetes medications (e.g., Linagliptin, Saxagliptin, Sitagliptin)
• grapefruit juice
• hepatitis C antivirals (e.g., daclatasvir, dasabuvir, ledipasvir, paritaprevir, ombitasvir, sofosbuvir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• Hydrocortisone
• ivermectin
• lidocaine
• Loperamide
• Losartan
• lumacaftor
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• maraviroc
• Mefloquine
• Methadone
• mifepristone
• milk thistle
• Mirtazapine
• Modafinil
• Nadolol
• nefazodone
• nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
• Norfloxacin
• Ondansetron
• Oxycodone
• phosphodiesterase 5 inhibitors (e.g., Sildenafil, Tadalafil, Vardenafil)
• praziquantel
• Primaquine
• protein kinase inhibitors (e.g., Crizotinib, Dasatinib, imatinib, Nilotinib)
• proton pump inhibitors (e.g., Lansoprazole, Omeprazole)
• Prucalopride
• quinidine
• quinine
• Ranitidine
• Repaglinide
• rifabutin
• rifampin
• rilpivirine
• Rivaroxaban
• Romidepsin
• St. John's wort
• seizure medications (e.g., Carbamazepine, Gabapentin, Levetiracetam, Phenytoin, primidone)
• selective serotonin reuptake inhibitors (SSRIs; e.g., Citalopram, Fluoxetine, Paroxetine, Sertraline)
• siltuximab
• Sirolimus
• "statin" anti-cholesterol medications (e.g., Atorvastatin, Lovastatin, Simvastatin)
• Tacrolimus
• tenofovir
• Teriflunomide
• Ticagrelor
• Ticlopidine
• Tocilizumab
• Tolterodine
• Tolvaptan
• Tramadol
• Trazodone
• tricyclic antidepressants (e.g., Amitriptyline, Clomipramine, Desipramine, Trimipramine)
• Venlafaxine
• Zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Galexos. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Galexos.

Birth control: The effect of simeprevir on the development of an unborn baby has not been studied, however it is often taken with medications that can cause severe birth defects to an unborn child. Both partners should use a reliable form of birth control while taking Galexos and for 6 months afterwards (the time it takes for ribavirin to be cleared from the body).

For women, your doctor will not give you simeprevir until you have had a negative pregnancy test. Your doctor should have you continue to do monthly pregnancy tests to ensure that you do not become pregnant while using Galexos.

Methods of birth control that use hormones, such as a birth control pill, patch, or injection, may not be fully reliable as simeprevir interacts with many medications and may change the way that your body uses the hormones. At least 2 forms of non-hormonal birth control (condom, diaphragm) must be used while you are taking Galexos.

Hepatitis B Reactivation: If you have had hepatitis B infection in the past, taking simeprevir may cause the hepatitis B to reactivate. This can cause liver damage, possible leading to the liver failure or death. Talk to your doctor if you have a history of hepatitis B infection.

Hepatitis C virus response: Only genotype 1 and genotype 4 hepatitis C virus strains have been studied and determined to respond to simeprevir. The safety and effectiveness of using simeprevir to treat other strains of hepatitis C virus have not been determined.

Infection with Human Immunodeficiency Virus (HIV): The safety and effectiveness of treatment with simeprevir have not been established for people who also have human immunodeficiency virus (HIV).

Lactose intolerance: Galexos contains lactose. If you have galactose intolerance (galactosemia, glucose-galactose malabsorption, or Lapp lactase deficiency) you should not take Galexos. Talk to your doctor about other alternatives.

Liver function: Simeprevir is not recommended for people with active, worsening liver disease, or moderately-to-severely reduced liver function. If you have a history of reduced liver function, discuss with your doctor how Galexos may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Galexos, and whether any special monitoring is needed.

Organ transplantation: The safety and effectiveness of treatment with simeprevir have not been established for people with liver or other organ transplants. Simeprevir may interact with medications used to prevent rejection of the transplanted organ.

Skin reactions: Simeprevir may cause skin rash or itchiness with or without a rash. It may also make your skin more sensitive to ultraviolet light from the sun or tanning beds. While you are taking simeprevir, avoid unnecessary exposure to sunlight. If you notice any unusual skin rash or peeling, contact your doctor.

Pregnancy: Simeprevir has not been studied for use by pregnant women and it must be taken with other antiviral medications, some of which have been shown to cause serious harm to the developing baby. Tell your doctor immediately if you become pregnant while using Galexos.

Breast-feeding: It is not known if simeprevir passes into breast milk. If you are a breast-feeding mother and are taking Galexos, it may affect your baby. Breast-feeding should be stopped before starting treatment with simeprevir.

Children: The safety and effectiveness of using Galexos have not been established for children.