An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

B vitamins

Giving 10 mg per day each of vitamins B1, B2, and B6 to elderly, depressed persons already on tricyclic antidepressants improved their depression and ability to think more than placebo did.¹ The subjects in this study were institutionalized, so it is unclear if these results apply to persons living at home.

L-tryptophan and Vitamin B3

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder.² These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.^{3 , 4}

Coenzyme Q10

A number of tricyclic antidepressants have been shown to inhibit enzymes that require coenzyme Q10 (CoQ10), a nutrient that is needed for normal heart function.⁵ It is therefore possible that CoQ10 deficiency may be a contributing factor to the cardiac side effects that sometimes occur with tricyclic antidepressants. Some practitioners advise patients taking tricyclic antidepressants to supplement with 30–100 mg of CoQ10 per day.

SAMe (S-adenosy-L-methionine)

SAMe may improve the clinical response to imipramine (Tofranil®). In a double-blind trial, depressive symptoms decreased earlier in the people who received SAMe injections (200 mg per day) in combination with imipramine than in those who received imipramine with placebo injections.⁶ Oral supplementation with SAMe has demonstrated antidepressant activity, independent of its combination with imipramine.⁷

St. John’s wort  (Hypericum perforatum)

Preliminary research has suggested that St. John’s wort may reduce blood levels of the tricyclic antidepressant amitriptyline.⁸ This may have occurred because certain chemicals found in St. John’s wort activate liver enzymes that are involved in the elimination of some drugs.^{9 , 10} Until more is known, people taking tricyclic antidepressants should avoid St. John’s wort.

Tea (Camellia sinensis)

Brewed black tea has been reported to cause precipitation of amitriptyline and imipramine in a test tube.¹¹ If this reaction occurred in the body, it could decrease absorption of these drugs. Until more is known, it makes sense to sePte ingestion of tea and tricyclic antidepressants by at least two hours.

Alcohol

Tricyclic antidepressants can cause drowsiness and dizziness.¹² Alcohol may intensify these actions, increasing the risk for accidental injury. People taking tricyclic antidepressants should avoid alcohol.