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Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)

Side Effects


The most common adverse reactions of fenfluramine are drowsiness, diarrhea, and dry mouth. Less frequent adverse reactions reported in association with fenfluramine are:

    Central nervous system: Dizziness; confusion; incoordination; headache; elevated mood; depression; anxiety, nervousness, or tension; insomnia; weakness or fatigue; increased or decreased libido; agitation, dysarthria.

    Gastrointestinal: Constipation; abdominal pain; nausea.

    Autonomic: Sweating; chills; blurred vision.

    Genitourinary: Dysuria; urinary frequency.

    Cardiovascular: Palpitation; hypotension; hypertension; fainting; pulmonary hypertension.

    Skin: Rash; urticaria; burning sensation.

    Miscellaneous: Eye irritation; myalgia; fever; chest pain; bad taste.

Drug Abuse and Dependence

Pondimin (fenfluramine hydrochloride) is a controlled substance in Schedule IV. Fenfluramine is related chemically to the amphetamines, although it differs somewhat pharmacologically. The amphetamines and related stimulant drugs have been extensively abused and can produce tolerance and severe psychological dependence, as well as other adverse organic and mental changes. In this regard, there has been a report of abuse of fenfluramine by subjects with a history of abuse of other drugs. Abuse of 80 to 400 milligrams of the drug has been reported to be associated with euphoria, derealization, and perceptual changes. Fenfluramine did not produce signs of dependence in animals and appears to produce sedation more often than CNS stimulation at therapeutic doses. Its abuse potential appears qualitatively different from that of amphetamines. The possibility that fenfluramine may induce dependence should be kept in mind when evaluating the desirability of including the drug in the weight reduction programs of individual patients.

Read the Pondimin (fenfluramine - removed from us market) Side Effects Center for a complete guide to possible side effects


Fenfluramine may increase slightly the effect of antihypertensive drugs, e.g., guanethidine, methyldopa, reserpine.

Other CNS depressant drugs should be used with caution in patients taking fenfluramine, since the effects may be additive.

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 12/8/2004

Side Effects

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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