McKinley Health Center - Pill Interactions with Other Drugs

Medications	Significance¹	Adverse Effects	Recommendations
Seizure Medications: e.g. Phenytoin (Dilantin) Mephenytoin (Mesantoin) Ethotoin (Peganone) Felbamate (Felbatol) Carbamazepine (Tegretol) Barbiturates (Pentobarbital, Phenobarbital, Primidone, Secobarbital, Amobarbital, Aprobarbital, Butabarbital, Butalbital, Mephobarbital) Sodium valproate (Depakene) does not appear to interfere with oral contraceptive therapy. Lamictal	····	Risk of pregnancy up to 25 times higher in OC users also using anticonvulsants. Decreased OC effectiveness. Changes in Lamictal levels; lowered during hormone pills and raised during reminber/placebo pills	Consider using alternative methods, altogether.
Central Nervous System: Modafinil (Provigil)	····	Increased risk of pregnancy.	Consider using alternative methods, altogether.
Antifungal Medications: Griseofulvin (Grisactin)	····	Breakthrough bleeding and unintended pregnancies have been reported.	Consider using alternative methods, altogether.
Azole Antifungals: Fluconazole (Diflucan) Ketoconazole (Nizoral) Itraconazole (Sporanox)	··	Some unintended pregnancies have been reported.	Use backup contraception.
Antibiotics: Rifampin	····	A high incidence of menstrual irregularities and a 6% pregnancy rate is seen on OCs.	Use an alternative or additional contraceptive method.
Troleandomycin	····	Possible liver problems.	Avoid Troleandomycin while on OCs.
All other antibiotics	·	Questionable association of increased pregnancy risk.	Consider using backup contraception during antibiotic treatment and for 7 days following treatment.
St. John's Wort	··	May lower blood concentration levels of hormones that suppress ovulation.	Avoid using St. John's Wort while on OCs.
Ascorbic acid (vitamin C)	·	May raise levels of estrogen in the blood.	Estrogen-related side effects may appear with vitamin C>1 gram.
¹Significance: Rated from highly significant (....) to weakly significant (.).

Medications	Significance²	Adverse Effects	Recommendations
Corticosteroids: Hydrocortisone Prednisone Prednisolone	····	Some steroids have reduced metabolism and higher blood levels when combined with OCs.	A reduction in steroid dose may be required.
Theophylline: Aminophylline Oxtriphylline	····	OCs may decrease the degradation of theophylline, while on OCs.	The theophylline level will need to be monitored.
Benzodiazepines: Alprazolam (Xanax) Chlordiazepoxide (Librium) Clonazepam (Klonopin) Diazepam (Valium) Flurazepam (Dalmane) Triazolam (Halcion)	···	OCs may raise blood levels of benzodiazepines.	A reduction in dose of benzodiazepines may be indicated.
Caffeine	···	OCs may reduce the metabolism of caffeine.	Watch for signs of caffeine overdose.
Beta-blockers: Metoprolol (Lopressor) Propranolol (Inderal)	··	OCs may raise blood levels of beta-blockers.	Close monitoring of the dose of beta-blockers is indicated.
Tricyclic Antidepressants: Amitriptyline (Elavil) Desipramine (Norpramin) Imipramine (Tofranil) Nortriptyline (Pamelor)	·	OCs may raise the blood levels of some tricyclic antidepressants.	Monitor the response to the tricyclic antidepressant.
Salicylate (Aspirin)	·	OCs may lower the blood levels of salicylates.	Aspirin doses may need to be adjusted upwards for women on maintenance doses of salicylates.
Acetaminophen (Tylenol)	·	OCs may lower the blood levels of acetaminophen.	Acetaminophen and OCs may be used together with little or no risk.
²Significance: Rated from highly significant (....) to weakly significant (.).

If you are a registered University of Illinois student and you have questions or concerns,
or need to make an appointment, please call: Dial-A-Nurse at 333-2700

If you are concerned about any difference in your treatment plan and the information in this handout,

you are advised to contact your health care provider.

Visit the McKinley Health Center Web site at: http://www.mckinley.uiuc.edu

HEd. III-129

07-11-07

pill_interactions_drugs