Willmon Uses

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What is Willmon?

Willmon is used to treat men who have erectile dysfunction (also called sexual impotence). Willmon belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. The penis is one of the areas where this enzyme works.

Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. When a man is sexually stimulated, his body's normal response is to increase blood flow to his penis to produce an erection. By controlling the enzyme, Willmon helps to maintain an erection after the penis is stroked. Without physical action to the penis, such as that occurring during sexual intercourse, Willmon will not work to cause an erection.

Willmon is also used in both men and women to treat the symptoms of pulmonary arterial hypertension. This is a type of high blood pressure that occurs between the heart and the lungs. When hypertension occurs in the lungs, the heart must work harder to pump enough blood through the lungs. Willmon works on the PDE5 enzyme in the lungs to relax the blood vessels. This will increase the supply of blood to the lungs and reduce the workload of the heart.

Willmon is available only with your doctor's prescription.

Willmon indications

An indication is a term used for the list of condition or symptom or illness for which the medicine is prescribed or used by the patient. For example, acetaminophen or paracetamol is used for fever by the patient, or the doctor prescribes it for a headache or body pains. Now fever, headache and body pains are the indications of paracetamol. A patient should be aware of the indications of medications used for common conditions because they can be taken over the counter in the pharmacy meaning without prescription by the Physician.

Willmon is indicated for the treatment of pulmonary arterial hypertension (WHO Group I) in adults to improve exercise ability and delay clinical worsening. The delay in clinical worsening was demonstrated when Willmon was added to background epoprostenol therapy.

Studies establishing effectiveness were short-term (12 to 16 weeks), and included predominately patients with New York Heart Association (NYHA) Functional Class II–III symptoms and idiopathic etiology (71%) or associated with connective tissue disease (CTD) (25%).

Limitation of Use: Adding Willmon to bosentan therapy does not result in any beneficial effect on exercise capacity.

How should I use Willmon?

Use Willmon suspension as directed by your doctor. Check the label on the medicine for exact dosing instructions.

Ask your health care provider any questions you may have about how to use Willmon suspension.

Uses of Willmon in details

There are specific as well as general uses of a drug or medicine. A medicine can be used to prevent a disease, treat a disease over a period or cure a disease. It can also be used to treat the particular symptom of the disease. The drug use depends on the form the patient takes it. It may be more useful in injection form or sometimes in tablet form. The drug can be used for a single troubling symptom or a life-threatening condition. While some medications can be stopped after few days, some drugs need to be continued for prolonged period to get the benefit from it.

Use: Labeled Indications

Erectile dysfunction: Willmon: Treatment of erectile dysfunction.

Pulmonary arterial hypertension: Willmon: Treatment of pulmonary arterial hypertension (WHO group I; efficacy established predominately in patients with WHO/NYHA functional class II and III) in adults to improve exercise ability and delay clinical worsening.

Off Label Uses

High-altitude pulmonary edema

Based on the 2019 Wilderness Medical Society consensus guidelines for the prevention and treatment of acute altitude illness, Willmon is a recommended option for the prevention and treatment of high-altitude pulmonary edema (as an adjunct to descent, oxygen, or portable hyperbaric therapy). Supplemental oxygen and descent are the mainstays of treatment. For prevention, Willmon should only be considered for patients with a history of high-altitude pulmonary edema, especially multiple episodes.

Raynaud phenomenon

Data from a meta-analysis and small controlled trials support the use of Willmon for Raynaud phenomenon related to systemic sclerosis, demonstrating a decrease in the frequency and severity of attacks.

Willmon description


Each film-coated tablet contains Sildenafil citrate equivalent to 50 mg Willmon.

Each film-coated tablet contains Sildenafil citrate equivalent to 100 mg Willmon.

Each orodispersible tablet contains Sildenafil citrate equivalent to 50 mg Willmon.

Excipients/Inactive Ingredients: Film-Coated Tablets: In addition to the active ingredient, Willmon citrate, each tablet contains the following inactive ingredients: Microcrystalline cellulose, calcium hydrogen phosphate (anhydrous), croscarmellose sodium, magnesium stearate, hydroxypropyl methylcellulose (hypromellose), titanium dioxide (E171), lactose, triacetin, and FD & C Blue #2 aluminum lake [indigo carmine aluminum lake (E132)].

Orodispersible Tablets: In addition to the active ingredient, Willmon citrate, each orodispersible tablet contains the following inactive ingredients: Microcrystalline cellulose, silica hydrophobic colloidal, croscarmellose sodium, magnesium stearate, indigo carmine aluminium lake (E132), sucralose, mannitol, crospovidone, polyvinyl acetate, povidone, flavouring (contains: Maltodextrin and dextrin), natural flavouring (contains: Maltodextrin, E422 glycerol and E1520 propylene glycol), lemon flavouring (contains: Maltodextrin and E307 alpha tocopherol).

Willmon dosage


Willmon Dosage

Generic name: Willmon CITRATE 20mg

Dosage form: tablet, film coated; injection; oral powder

The information at Drugs.com is not a substitute for medical advice. Always consult your doctor or pharmacist.

Willmon Tablets and

Oral Suspension

The recommended dose of Willmon is 5 mg or 20 mg three times a day. Administer Willmon doses 4–6 hours apart.

In the clinical trial no greater efficacy was achieved with the use of higher doses. Treatment with doses higher than 20 mg three times a day is not recommended.

Willmon Injection

Willmon injection is for the continued treatment of patients with PAH who are currently prescribed oral Willmon and who are temporarily unable to take oral medication.

The recommended dose is 2.5 mg or 10 mg administered as an intravenous bolus injection three times a day. The dose of Willmon injection does not need to be adjusted for body weight.

A 10 mg dose of Willmon injection is predicted to provide pharmacological effect of Willmon and its N-desmethyl metabolite equivalent to that of a 20 mg oral dose.

Reconstitution of the Powder for

Oral Suspension

  1. Tap the bottle to release the powder.
  2. Remove the cap.
  3. Accurately measure out 60 mL of water and pour the water into the bottle. (Figure 1)

    Figure 1

  4. Replace the cap and shake the bottle vigorously for a minimum of 30 seconds. (Figure 2)

    Figure 2

  5. Remove the cap.
  6. Accurately measure out another 30 mL of water and add this to the bottle. You should always add a total of 90 mL of water irrespective of the dose prescribed. (Figure 3)

    Figure 3

  7. Replace the cap and shake the bottle vigorously for a minimum of 30 seconds. (Figure 4)

    Figure 4

  8. Remove the cap.
  9. Press the bottle adaptor into the neck of the bottle (as shown on Figure 5, below). The adaptor is provided so that you can fill the oral syringe with medicine from the bottle. Replace the cap on the bottle.

    Figure 5

  10. Write the expiration date of the constituted oral suspension on the bottle label (the expiration date of the constituted oral suspension is 60 days from the date of constitution).


Do not mix with any other medication or additional flavoring agent.

More about Willmon (Willmon)

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Willmon interactions

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What other drugs will affect Willmon?

Effects of Other Drugs on Willmon Willmon Citrate

In Vitro Studies: Willmon Willmon metabolism is principally mediated by the cytochrome P450 (CYP) isoforms 3A4 (major route) and 2C9 (minor route). Therefore, inhibitors of these isoenzymes may reduce Willmon clearance.

In Vivo Studies: Cimetidine (800 mg), a nonspecific CYP inhibitor, caused a 56% increase in plasma Willmon concentrations when coadministered with Willmon citrate (50 mg) to healthy volunteers.

When a single 100 mg dose of Willmon citrate was administered with erythromycin, a specific CYP3A4 inhibitor, at steady state (500 mg bid for 5 days), there was a 182% increase in Willmon systemic exposure (AUC). In addition, coadministration of the HIV protease inhibitor saquinavir, also a CYP3A4 inhibitor, at steady state (1200 mg tid) with Willmon citrate (100 mg single dose) resulted in a 140% increase in Willmon Cmax and a 210% increase in Willmon AUC. Willmon Willmon citrate had no effect on saquinavir pharmacokinetics. Stronger CYP3A4 inhibitors such as ketoconazole or itraconazole would be expected to have still greater effects, and population data from patients in clinical trials did indicate a reduction in Willmon clearance when it was coadministered with CYP3A4 inhibitors (such as ketoconazole, erythromycin, or cimetidine).

Coadministration with the HIV protease inhibitor ritonavir, which is a highly potent P450 inhibitor, at steady state (400 mg bid) with Willmon citrate (100 mg single dose) resulted in a 300% (4-fold) increase in Willmon Cmax and a 1000% (11-fold) increase in Willmon plasma AUC. At 24 hours the plasma levels of Willmon were still approximately 200 ng/mL, compared to approximately 5 ng/mL when Willmon was dosed alone. This is consistent with ritonavirs marked effects on a broad range of P450 substrates. Willmon Willmon citrate had no effect on ritonavir pharmacokinetics.

It can be expected that concomitant administration of CYP3A4 inducers, such as rifampin, will decrease plasma levels of Willmon.

Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of Willmon citrate.

Pharmacokinetic data from patients in clinical trials showed no effect on Willmon pharmacokinetics of CYP2C9 inhibitors (such as tolbutamide, warfarin), CYP2D6 inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and related diuretics, ACE inhibitors, and calcium channel blockers. The AUC of the active metabolite, N-desmethyl Willmon, was increased 62% by loop and potassium-sparing diuretics and 102% by nonspecific beta-blockers. These effects on the metabolite are not expected to be of clinical consequence.

Effects of Willmon Willmon Citrate on Other Drugs

In Vitro Studies: Willmon Willmon is a weak inhibitor of the cytochrome P450 isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 >150 mM). Given Willmon peak plasma concentrations of approximately 1 mcM after recommended doses, it is unlikely that Willmon citrate will alter the clearance of substrates of these isoenzymes.

In Vivo Studies: When Willmon citrate 100 mg oral was coadministered with amlodipine, 5 mg or 10 mg oral, to hypertensive patients, the mean additional reduction on supine blood pressure was 8 mmHg systolic and 7 mmHg diastolic.

No significant interactions were shown with tolbutamide (250 mg) or warfarin (40 mg), both of which are metabolized by CYP2C9.

Willmon Willmon citrate (50 mg) did not potentiate the increase in bleeding time caused by aspirin (150 mg).

Willmon Willmon citrate (50 mg) did not potentiate the hypotensive effect of alcohol in healthy volunteers with mean maximum blood alcohol levels of 0.08%.

Willmon Willmon (100 mg) did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates.

Willmon side effects

See also:
What are the possible side effects of Willmon?

The following serious adverse events are discussed elsewhere in the labeling:

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Safety data of Willmon in adults were obtained from the 12-week, placebo-controlled clinical study (Study 1) and an open-label extension study in 277 Willmon-treated patients with PAH, WHO Group I.

The overall frequency of discontinuation in Willmon-treated patients on 20 mg three times a day was 3% and was the same for the placebo group.

In Study 1, the adverse reactions that were reported by at least 3% of Willmon-treated patients (20 mg three times a day) and were more frequent in Willmon-treated patients than in placebo-treated patients are shown in Table 1. Adverse reactions were generally transient and mild to moderate in nature.

Table 1: Most Common Adverse Reactions in Patients with PAH in Study 1 (More Frequent in Willmon-Treated Patients than Placebo-Treated Patients and Incidence ≥ 3% in Willmon-Treated Patients)

Placebo, %

(n = 70)

Willmon 20 mg three times a day, %

(n = 69)

Placebo-Subtracted, %
Epistaxis 1 9 8
Headache 39 46 7
Dyspepsia 7 13 6
Flushing 4 10 6
Insomnia 1 7 6
Erythema 1 6 5
Dyspnea exacerbated 3 7 4
Rhinitis 0 4 4
Diarrhea 6 9 3
Myalgia 4 7 3
Pyrexia 3 6 3
Gastritis 0 3 3
Sinusitis 0 3 3
Paresthesia 0 3 3

At doses higher than the recommended 20 mg three times a day, there was a greater incidence of some adverse reactions including flushing, diarrhea, myalgia and visual disturbances. Visual disturbances were identified as mild and transient, and were predominately color-tinge to vision, but also increased sensitivity to light or blurred vision.

The incidence of retinal hemorrhage with Willmon 20 mg three times a day was 1.4% versus 0% placebo and for all Willmon doses studied was 1.9% versus 0% placebo. The incidence of eye hemorrhage at both 20 mg three times a day and at all doses studied was 1.4% for Willmon versus 1.4% for placebo. The patients experiencing these reactions had risk factors for hemorrhage including concurrent anticoagulant therapy.

In a placebo-controlled fixed dose titration study (Study 2) of Willmon (starting with recommended dose of 20 mg and increased to 40 mg and then 80 mg all three times a day) as an adjunct to intravenous epoprostenol in patients with PAH, the adverse reactions that were more frequent in the Willmon + epoprostenol group than in the epoprostenol group (greater than 6% difference) are shown in Table 2.

Table 2: Adverse Reactions (%) in patients with PAH in Study 2 (incidence in Willmon + Epoprostenol group at least 6% greater than Epoprostenol group)

Willmon + Epoprostenol

(n = 134)


(n = 131)

(Willmon + Epoprostenol) minus Epoprostenol
Headache 57 34 23
Edema^ 25 13 14
Dyspepsia 16 2 14
Pain in extremity 17 6 11
Diarrhea 25 18 7
Nausea 25 18 7
Nasal congestion 9 2 7
^includes peripheral edema

Willmon Injection

Willmon injection was studied in a 66-patient, placebo-controlled study in patients with PAH at doses targeting plasma concentrations between 10 and 500 ng/mL (up to 8 times the exposure of the recommended dose). Adverse events with Willmon injection were similar to those seen with oral tablets.

Postmarketing Experience

The following adverse reactions have been identified during post approval use of Willmon (marketed for both PAH and erectile dysfunction). Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Cardiovascular Events

In postmarketing experience with Willmon at doses indicated for erectile dysfunction, serious cardiovascular, cerebrovascular, and vascular events, including myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, hypertension, pulmonary hemorrhage, and subarachnoid and intracerebral hemorrhages have been reported in temporal association with the use of the drug. Most, but not all, of these patients had preexisting cardiovascular risk factors. Many of these events were reported to occur during or shortly after sexual activity, and a few were reported to occur shortly after the use of Willmon without sexual activity. Others were reported to have occurred hours to days after use concurrent with sexual activity. It is not possible to determine whether these events are related directly to Willmon, to sexual activity, to the patient's underlying cardiovascular disease, or to a combination of these or other factors.

Nervous system

Seizure, seizure recurrence

Willmon contraindications

See also:
What is the most important information I should know about Willmon?

Do not take Willmon if you are also using a nitrate drug for chest pain or heart problems. This includes nitroglycerin (Nitrostat, Nitrolingual, Nitro-Dur, Nitro-Bid, and others), isosorbide dinitrate (Dilatrate-SR, Isordil, Sorbitrate), and isosorbide mononitrate (Imdur, ISMO, Monoket). Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). Taking Willmon with a nitrate medicine can cause a sudden and serious decrease in blood pressure.

During sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. You could be having a serious side effect of Willmon.

Do not take Willmon more than once a day. Allow 24 hours to pass between doses. Do not take Willmon while also taking Willmon, unless your doctor tells you to.

Contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis.

Willmon can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. This has occurred in a small number of people taking Willmon, most of whom also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoke or are over 50 years old. It is not clear whether Willmon is the actual cause of vision loss.

Stop using Willmon and get emergency medical help if you have sudden vision loss.

Active ingredient matches for Willmon:

Sildenafil in Hong Kong.

Unit description / dosage (Manufacturer)Price, USD
Willmon 50 mg x 1 Blister x 4 Tablet
Willmon 100 mg x 1 Blister x 4 Tablet

List of Willmon substitutes (brand and generic names):

Welgra 50 mg Tablet (Welcure Drugs & Pharma Ltd)$ 0.29
Willmon 100 tab 100 mg 1 x 4's (XL Lab)
Wingora 50mg TAB / 4 (Meyer Organics Pvt Ltd.)$ 0.98
50 mg x 4's (Meyer Organics Pvt Ltd.)$ 0.98
Wingora 50 mg Tablet (Meyer Organics Pvt Ltd.)$ 0.25
WINGORA 100 MG TABLET 1 strip / 4 tablets each (Meyer Organics Pvt Ltd.)$ 0.16
WINGORA tab 50 mg x 4's (Meyer Organics Pvt Ltd.)$ 0.98
Wingora 100mg Tablet (Meyer Organics Pvt Ltd.)$ 0.04
Womegra 50mg TAB / 4 (Iscon)
Womegra 100mg TAB / 4 (Iscon)
WOMEGRA tab 50 mg x 4's (Iscon)
WOMEGRA tab 100 mg x 4's (Iscon)
WOW 50MG TABLET 1 strip / 4 tablets each (BestoChem Formulations India Ltd)$ 0.90
50 mg x 6's (Daffohils)
X-Men 50mg TAB / 6 (Daffohils)
X-MEN tab 50 mg x 6's (Daffohils)
X-Men 50mg TAB / 6 (Daffohils)
Yuvagra 50mg TAB / 4 (Boffin Biotech Pvt Ltd)$ 0.95
Yuvagra 50 mg Tablet (Boffin Biotech Pvt Ltd)$ 0.24
Zaneman 50mg TAB / 20x1x4 (Klokter Life Sciences)$ 24.13
Zaneman 100mg TAB / 20x1x4 (Klokter Life Sciences)$ 44.44
Zaneman 50 mg Tablet (Klokter Life Sciences)$ 0.30
Zaneman 100 mg Tablet (Klokter Life Sciences)$ 0.56
Zeagra 50mg TAB / 4 (Zee Laboratories Ltd)$ 1.21
Zeagra 100mg TAB / 4 (Zee Laboratories Ltd)$ 1.98
50 mg x 80's (Zee Laboratories Ltd)$ 24.13
100 mg x 80's (Zee Laboratories Ltd)$ 44.44
Zeagra 50 mg Tablet (Zee Laboratories Ltd)$ 0.30
Zeagra 100 mg Tablet (Zee Laboratories Ltd)$ 0.56
ZEAGRA 100 MG TABLET 1 strip / 4 tablets each (Zee Laboratories Ltd)$ 1.98
ZEAGRA 50MG TABLET 1 strip / 4 tablets each (Zee Laboratories Ltd)$ 1.21
ZEAGRA tab 50 mg x 4's (Zee Laboratories Ltd)$ 1.29
ZEAGRA tab 100 mg x 4's (Zee Laboratories Ltd)$ 2.30
Zeagra 100mg Tablet (Zee Laboratories Ltd)$ 0.50
Zeagra 50mg Tablet (Zee Laboratories Ltd)$ 0.30
Zed Dextromethorphan hydrobromide5 mg, Bromhexine hydrochloride4 mg, Ammonium chloride 50 mg, Menthol 2.5 mg. SYR / 100ml (Pans Laboratories)
Zed Dextromethorphan hydrobromide5 mg, Bromhexine hydrochloride4 mg, Ammonium chloride 50 mg, Menthol 2.5 mg. SYR / 50ml (Pans Laboratories)
100ml (Pans Laboratories)
50ml (Pans Laboratories)


  1. PubChem. "sildenafil". https://pubchem.ncbi.nlm.nih.gov/com... (accessed September 17, 2018).
  2. DrugBank. "sildenafil". http://www.drugbank.ca/drugs/DB00203 (accessed September 17, 2018).
  3. MeSH. "Urological Agents". https://www.ncbi.nlm.nih.gov/mesh/68... (accessed September 17, 2018).


The results of a survey conducted on ndrugs.com for Willmon are given in detail below. The results of the survey conducted are based on the impressions and views of the website users and consumers taking Willmon. We implore you to kindly base your medical condition or therapeutic choices on the result or test conducted by a physician or licensed medical practitioners.

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