Last updated on RxList: 2/12/2021
Ionamin Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Ionamin?

Ionamin (phentermine resin) is a stimulant used together with diet and exercise to treat obesity (overweight) in people with risk factors such as:

The brand name Ionamin is discontinued, but generic versions may be available.

What Are Side Effects of Ionamin?

Common side effects of Ionamin (phentermine resin) include:

  • dizziness,
  • dry mouth or unpleasant taste in the mouth,
  • difficulty sleeping (insomnia),
  • irritability,
  • restlessness,
  • hyperactivity,
  • nausea,
  • vomiting,
  • diarrhea,
  • constipation,
  • headache,
  • tremors,
  • increased or decreased interest in sex, or impotence

Dosage for Ionamin

The dose of Ionamin is one capsule daily, before breakfast or 10-14 hours before retiring.

Ionamin In Children

Ionamin is not approved for use in children.

What Drugs, Substances, or Supplements Interact with Ionamin?

Ionamin may interact with blood pressure medications, insulin or oral diabetes medications, guanethidine, or antidepressants. Tell your doctor all medications and supplements you use.

Ionamin During Pregnancy and Breastfeeding

Ionamin must not be used during pregnancy. It may harm a fetus. If you are pregnant or think you may be pregnant, tell your doctor. This drug may pass into breast milk and could have undesirable effects on a nursing infant. Breastfeeding is not recommended while using this drug.

Additional Information

Withdrawal symptoms may occur if you suddenly stop taking this medication.

Our Ionamin (phentermine resin) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Ionamin Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • feeling short of breath, even with mild exertion;
  • chest pain, feeling like you might pass out;
  • swelling in your ankles or feet;
  • pounding heartbeats or fluttering in your chest;
  • tremors, feeling restless, trouble sleeping;
  • unusual changes in mood or behavior; or
  • increased blood pressure--severe headache, blurred vision, pounding in your neck or ears, anxiety, nosebleed.

Common side effects may include:

  • itching;
  • dizziness, headache;
  • dry mouth, unpleasant taste;
  • diarrhea, constipation, stomach pain; or
  • increased or decreased interest in sex.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Ionamin (Phentermine Capsules)

Ionamin Professional Information


Cardiovascular: Primary pulmonary hypertension (see WARNINGS), palpitation, tachycardia, elevation of blood pressure.

Central Nervous System: Overstimulation, restlessness, dizziness, insomnia, euphoria, dysphoria, tremor, headache; rarely psychotic episodes at recommended doses with some drugs in this class.

Gastrointestinal: Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal disturbances.

Allergic: Urticaria.

Endocrine: Impotence, changes in libido.

Read the entire FDA prescribing information for Ionamin (Phentermine Capsules)

© Ionamin Patient Information is supplied by Cerner Multum, Inc. and Ionamin Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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