Ionamin is a prescription-only weight-loss medication that contains phentermine resin as its active ingredient.

Phentermine suppresses appetite and boosts energy, while the resin creates a slow-release medication to prolong the drug’s effects. Ionamin is no longer sold in the US.


Ionamin is a prescription weight-loss drug for overweight and obese patients. It suppresses feelings of hunger by acting on parts of the central nervous system. 

Who Can Take Ionamin?

woman weighing herself on a bathroom scale
Ionamin is designed for the short-term management of exogenous obesity

This medication is prescribed for obese patients with an initial BMI (body mass index) of 30+, or those with a BMI of 27 or above if other risk factors are present (e.g., hypertension, diabetes, hyperlipidemia).

Ionamin is designed as a short-term treatment and should always be used as an adjunct to healthy lifestyle changes like portion control, regular physical activity, and stress management. 

Phentermine is not recommended for:

  • Children of 18 years or younger
  • The elderly

Is Ionamin a prescription or an over-the-counter drug?

Ionamin is a prescription-only medication.

Phentermine, the active ingredient, has a chemical makeup similar to that of amphetamine, which makes stimulant abuse a concern. Furthermore, these pills may be habit-forming and should not but used for longer than a few weeks at a time.

Phentermine is a schedule IV controlled substance in the US and abroad, so it is illegal to buy or sell Ionamin online or without a doctor’s prescription.


Ionamin capsules are available in two strengths: 15mg and 30mg.

Ionamin 15mg: yellow/grey capsules imprinted with “IONAMIN 15.” Supplied in bottles of 100’s and 400’s

Ionamin 30 mg: yellow capsules, imprinted with “IONAMIN 30.” Supplied in bottles of 100’s and 400’s

Specific Ingredients

15 mg Capsules

  • 15 mg of phentermine
  • D&C Yellow No. 10
  • Dibasic calcium phosphate
  • FD&C Yellow No. 6
  • Gelatin
  • Iron oxides (15 mg capsules only)
  • Lactose
  • Magnesium stearate
  • Titanium dioxide

30 mg Capsules

  • 30 mg of phentermine
  • D&C Yellow No. 10
  • Dibasic calcium phosphate
  • FD&C Yellow No. 6
  • Gelatin
  • Iron oxides (15 mg capsules only)
  • Lactose
  • Magnesium stearate
  • Titanium dioxide

Side Effects

doctor measuring patient's blood pressure
A doctor will monitor your blood pressure and check for other Ionamin side effects

Ionamin, like other brands of phentermine, can cause a wide variety of side effects.

Serious potential side effects include:

  • Difficulty in breathing
  • Lightheadedness
  • Weakness
  • Ankle and extremity swelling
  • Increase in blood pressure
  • Excessive fatigue
  • Euphoria, or other dramatic changes in mood

Seek immediate medical attention if you or someone you know experiences any of these symptoms while taking Ionamin.

Common side effects of Ionamin include:

  • Headache
  • Dryness of the mouth
  • Unpleasant taste
  • Diarrhea
  • Constipation
  • Impotence
  • Changes in libido
  • Restlessness
  • Excess energy
  • Insomnia
  • Dysphoria (“phen rage”)


Most patients take one capsule per day approximately 1-2 hours before or after their breakfast. Ionamin capsules should be swallowed whole and with plenty of water.

Do not take this medication late in the day because the phentermine increases energy levels and can cause insomnia.

The exact dosage varies from person to person. Your doctor will prescribe the proper dosage for you.

Never take Ionamin for longer or at a higher dosage than prescribed.


Seek immediate medical attention if you or someone you know takes too much Ionamin.

A phentermine overdose can cause serious consequences, including death.

Common symptoms of overdosage include unusually high energy levels, tremors, hyperreflexia, increased breathing rate, confusion, assaultiveness, hallucinations, panic, extreme tiredness, depression, arrhythmia, hypertension or hypotension, circulatory collapse, nausea and sickness, diarrhea, and abdominal cramps.


Always tell your doctor about all pre-existing conditions and other medications/supplements

It’s important that your prescribing doctor has a complete picture of your past and present health. For this reason, tell your doctor about:

  • Your complete medical history, especially if it includes high blood pressure, a heart condition, arteriosclerosis, overactive thyroid, diabetes, glaucoma, or drug abuse
  • Any allergies that you may have, especially so if you have a known allergy to phentermine
  • Any medicines or supplements you have taken in the last two weeks (both prescription and over-the-counter)
  • All plans for conception, breastfeeding, etc. This medication is not appropriate if you are pregnant, nursing, or trying to conceive. Tell your doctor right away if you become pregnant while undergoing treatment
  • Any proclivity to agitated states

Read more about phentermine precautions & contraindications.

User Reviews

Wondering what real users thought of Ionamin? This brand of phentermine was unique because of it’s extended-release formulation, but patients reported varying levels of effectiveness.

Ionamin has an average user rating of 4.2/5:

Who Makes Ionamin?

Ionamin was manufactured and distributed by:

Celltech Pharmaceuticals, Inc.
Rochester, NY 14623 USA