Penicillamine may increase vitamin B6 excretion, reduce activity, and increase the risk for vitamin B6 deficiency.¹ It makes sense for people taking penicillamine to supplement with small (5–20 mg per day) amounts of vitamin B6. Some researchers have suggested that as much as 50 mg per day of vitamin B6 may be necessary.²

Penicillamine therapy has been associated with sodium depletion.³ The frequency of this association remains unclear.

One report found bromelain improved the action of antibiotic drugs, including penicillin and erythromycin, in treating a variety of infections. In that trial, 22 out of 23 people who had previously not responded to the antibiotics did so after adding bromelain four times per day.⁴ Doctors will sometimes prescribe enough bromelain to equal 2,400 gelatin dissolving units (listed as GDU on labels) per day. This amount would equal approximately 3,600 MCU (milk clotting units), another common measure of bromelain activity.

Penicillamine binds iron. When taken with iron, penicillamine absorption and activity are reduced.⁵ Four cases of penicillamine-induced kidney damage were reported when concomitant iron therapy was stopped, which presumably led to the increased penicillamine absorption and toxicity.⁶

People taking penicillamine should discuss with their doctor whether it would be appropriate to take a zinc supplement (at a separate time of day from the penicillamine).⁷ However, people taking penicillamine should not supplement with zinc, unless they are being supervised by a doctor.

In a double-blind study with ten healthy people, guar gum reduced penicillin absorption.⁸ Until more is known, to avoid this interaction, people taking penicillin should take it two hours before or after any guar gum-containing supplements. It remains unclear whether the smaller amounts of guar gum found in many processed foods would have a significant effect.

One of the main uses of penicillamine is to reduce toxic copper deposits in people with Wilson’s disease. People taking a copper supplement can make Wilson’s disease worse and may negate the benefits of drugs used to remove copper from the body.