Susten 400 Mg

Last Updated on 06/08/2026 ✔ Medically Reviewed by Dr. Arjun Srivastav

What is Susten 400 mg?

Susten 400 mg is an orally administered slight yellow coloured drug containing micronised natural progesterone, which is an artificial substitute for the main female sex hormone.

This medication is prescribed mainly in the field of gynaecology and obstetrics to treat any health issue that results from a lack of progesterone in a woman’s body.

Doctors prescribe Susten 400 mg for several specific medical reasons:

Pregnancy Support: Here, it is given to newly pregnant mothers to keep up with normal hormonal levels to avoid the chances of miscarriage.

Infertility Treatment: In case of female infertility issues, this medicine can be specifically given before conducting IVF procedures.

Menstrual disorders: In cases of women with missed or irregular periods, this medicine can help make the menstrual cycle regular in females.

HRT: Along with other estrogen therapies, this medicine is given to women who have just attained the stage of menopause in their lives and are having some side effects like flushing, weakness and so on.

Manufacturer

Sun Pharmaceutical Industries Ltd is the original brand manufacturer of the brand name Susten 400 mg Capsule.

Composition and appearance

• Active ingredient: Each medicine has a dose of 400 mg of natural micronised progesterone hormone.
• Inactive ingredients: The hormone is suspended in an oily base and in a gelatin shell with preservatives and drug stabilizers for long-term storage of the capsule.
• Appearance: A sachet of Susten 400 mg contains 10 medicines in it. The colour of each medicine is off-white to slightly pale yellow in colour and is oval or egg-shaped.

Onset of action

• Time to reach maximum levels in blood: Oral medicines usually begin absorption and pass through the liver, after which it is activated in the bloodstream within about 1 to 3 hours of use.
• Starting periods: Bleeding and period cycle can usually begin within 2 to 5 days of taking the last medicine.
• Pregnancy support: In case of supporting pregnancy, the medicine works rapidly and begins to thicken the uterine lining within 24 hours of taking the first dose.

How does Susten 400 mg work?

Mimicking actual progesterone actions

Its composition is similar to that synthesised by your body; thus, it binds itself to the receptors, triggering particular genes associated with the development of tissues and hormones.

During IVF & early pregnancy

Susten ensures that the endometrium takes up this mature and receptive form in order to allow a successful implantation.

As a Miscarriage Preventive Measure

Susten works by relaxing the smooth muscles of the uterus; thus, any chance of miscarriage or pre-term labour due to early uterine contractions or spasms is prevented.

Inducing Menstruation

Once you start taking Susten 400 mg Soft Gelatin Capsule for several days at a time and menstruation suddenly stops, a sharp decrease in progesterone occurs within your body.

Consequently, your body triggers the same natural reaction, which causes your endometrium to shed, resulting in an artificial menstrual period.

Dosage of Susten 400 mg Capsule

• Inducing regular periods: A single dose of 400 mg taken 1 time each day for 10 days.
• For uterine thickening: A dose of 200mg taken 2 times each day for 12 days.

Missed doses

If you miss a dose, take it as soon as you remember, but if the next dose is close, do not take two doses.

Overdose

Overdose symptoms include excessive drowsiness, dizziness, and an abnormal hormonal response.

Benefits of Susten 400 Mg

Prevents Miscarriage

It helps to provide the necessary hormones to women who have had multiple miscarriages in the past and threatened abortions to maintain the endometrial health.

Prevents Premature Delivery

Being a relaxant for the uterine muscles, it prevents their contraction and thereby, the risk of delivery before the due date.

Necessary for IVF

Assisted reproductive technique is where the natural production of progesterone by the body may be reduced. Susten 400 Capsule plays an important role in such cases in making the body ready for pregnancy and embryo implantation.

Helps with Amenorrhea (Missed Periods)

Women with amenorrhea (due to the absence of ovulation) will find that Susten works like the latter phase of a natural menstrual cycle and thus gives rise to a predictable withdrawal period after completion of the treatment.

Controls Irregular Uterine Bleeding

This medicine ensures proper thickness of the inner layer of the uterus (endometrium), thus eliminating the problems of abnormal or heavy bleeding caused by estrogen.

Protects against Endometrial Cancer

Alone, the use of estrogen leads to an increased thickness of the endometrium, putting one at risk of endometrial cancer. Susten prevents the risk of endometrial hyperplasia leading to endometrial cancer.

Which Progesterone Capsule Is Best for Irregular Periods?

Lower-dose progesterone may sometimes be sufficient.

Doctors may choose:

• Susten 200 mg
• Susten 400 mg
• Other progesterone brands
• Synthetic progestins

The decision depends on whether the issue is:

• PCOS
• Hormonal imbalance
• Perimenopause
• Progesterone deficiency

Susten 400 mg for PCOS and Irregular Periods

Women with PCOS often experience irregular ovulation, which can affect progesterone production.

Susten may sometimes be used to:

• Support progesterone replacement after ovulation-related deficiency
• Help regulate withdrawal bleeding in selected treatment plans
• Improve cycle control

It does not cure PCOS but may support hormone management.

Drug Interactions

Medications that Decrease Susten’s Effectiveness

1. Medicines for seizures – Carbamazepine, Phenytoin
2. Antibiotic medicines – Rifampicin
3. HIV treating medicines – Nevirapine, Nelfinavir
4. Herbal supplements – St. John’s Wort

Medications that Increase Susten’s Side Effects

• Medicines for fungal infections – Voriconazole and itraconazole
• Antibiotics – Clarithromycin

Susten 400 mg Side Effects

Common side effects

• Vomiting: Can occur for a few days, but the patient usually gets well on their own within two to 3 days.
• Stomach pain, bloating: Can occur for a few days, where patients can take a light meal before taking the medicine.
• Swelling: Occurs as a common side effect but may get intense if taken as an overdose.
• Headache, dizziness: Take rest and consult with a doctor if it repeats or gets intense.

Severe side effects

• Abnormal vaginal bleeding: Stop taking the medicine and get treatment from the doctor.
• Vaginal yeast infection: Notice the signs of inflammation, rashes, and redness around the vagina and immediately talk to a doctor.

Precautions and Warnings

Can make you feel drowsy

Using Susten 400 mg, most patients can feel drowsy and dizzy during the entire tenure. Avoid doing major activities where there is a risk of injury or accident.

Avoid stopping it suddenly

Never stop taking your pills suddenly when the doctors have given them as a course of a few days. This can increase the risk of uterine bleeding, putting pregnancy at risk.

Warnings for other health issues

Even though patients can use medicine in case of the following health issues, they come under the high-risk category. In such cases, the doctors may adjust the dose, change it frequently, and ask you to come for regular health checkups.

These health issues include-

• Heart Disorders: Having heart disorders, where progesterone is regularly administered, can increase fluid retention and cause high BP.
• Diabetes: Diabetes, as progesterone can cause insulin insensitivity that can raise your blood sugar levels
• Renal and Lungs Issues: Asthma, migraine, and kidney disorder, as intake of progesterone causes fluid retention, which can affect your health in several ways.
• Depression: Depression, as with progesterone, can cause dizziness and drowsiness issues, which can affect your mental health.

When not to use?

In case of some health issues: Doctors do not recommend women to use Susten 400 mg when they have health issues like-

• • Unknown vaginal bleeding
  • Currently suffering from or have a history of having blood clots
  • Severe liver disease, like cirrhosis
  • History of cancer suffering in the uterus and breast

In case of hypersensitivity: Rarely, some women can build hypersensitivity to the drug and end up with severe allergic side effects of anaphylaxis, which can cause issues like-

• • Rashes
  • Difficulty breathing
  • Swelling and inflammation in the face and throat

In case of some severe side effects: Immediately contact your doctor and stop taking Susten 400 mg from the next dose onwards if you notice side effects like-

• • Signs of blood clots, such as pain in the limbs
  • Signs of pulmonary embolism – Shortness of breath, chest pain, coughing up blood
  • Signs of stroke – chest pain, palpitations, sweating
  • Vision changes

Storage and disposal

Store the Susten 400 mg capsules safely in normal room temperature and less humid areas. Avoid wet places, as the capsule can turn soggy.

Keep checking the expiry date on the sachet and avoid using medicines once they have expired. Dispose of such unused medicines and empty sachets in a disposal bag.

Where to buy Susten 400 Mg in Australia?

To buy Susten 400 mg in Australia, check out the local medicine stores in your area. If you want to shop online, Australiarxmeds is a good website, which is licensed and gives doorstep delivery.