Preliminary information suggests that muscle damage sometimes caused by AZT is at least partially due to depletion of carnitine in the muscles by the drug.⁸ It has been reported that most patients taking AZT have depleted carnitine levels that can be restored with carnitine supplementation (6 grams per day).⁹

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{10 , 11 , 12} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.¹³ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.¹⁴ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{16 , 17 , 18} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.¹⁹ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.²⁰ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{21 , 22 , 23} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.²⁴ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.²⁵ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{26 , 27 , 28} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.²⁹ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.³⁰ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{31 , 32 , 33} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.³⁴ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.³⁵ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{36 , 37 , 38} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.³⁹ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.⁴⁰ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{41 , 42 , 43} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.⁴⁴ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.⁴⁵ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{46 , 47 , 48} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.⁴⁹ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.⁵⁰ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

Animal research suggests carnitine may prevent doxorubicin’s toxicity.¹⁵

People who have Duchenne muscular dystrophy have low levels of L-carnitine in their muscles. Allopurinol restores L-carnitine to normal levels, resulting in improved muscle strength.⁵¹ Whether L-carnitine supplementation might improve this effect of allopurinol has not been investigated.

Several controlled and preliminary studies showed that multiple drug therapy for seizures results in dramatic reductions in blood carnitine levels.^{52 , 53 , 54} Further controlled research is needed to determine whether children taking anticonvulsants might benefit by supplementing with L-carnitine, since current studies yield conflicting results. For example, one controlled study indicated that children taking valproic acid and carbamazepine received no benefit from supplementing with L-carnitine.⁵⁵ However, another small study revealed that children taking valproic acid experienced less fatigue and excessive sleepiness following L-carnitine supplementation.⁵⁶ Despite the lack of well-controlled studies, individuals who are taking anticonvulsants and experiencing side effects might benefit from supplementing with L-carnitine.

One controlled study showed that taking phenobarbital resulted in reduced blood levels of L-carnitine.⁵⁷ Further research is needed to determine whether people taking phenobarbital might benefit from supplemental L-carnitine. Based on the currently available information, some healthcare practitioners may recommend monitoring L-carnitine blood levels or supplementing with L-carnitine.

Valproic acid causes depletion of carnitine in children,⁵⁸ and blood carnitine levels are often low in people taking valproic acid for long periods of time. While there have been several case reports of valproic acid-related carnitine deficiency causing abdominal pain in children, there is controversy about the need for carnitine supplements in children taking valproic acid.^{59 , 60 , 61}

Complete disappearance of severe valproic acid-induced abdominal pain was achieved in one child with intractable epilepsy immediately following the introduction of 300 mg per day of L-carnitine.⁶² Carnitine supplementation (50 mg per 2.2 pounds of body weight) has protected children from valproic acid-induced increases in blood ammonia levels in some research,⁶³ though other published work has questioned whether the depletion of carnitine and the increase in blood ammonia levels (both caused by valproic acid) are actually related to each other.⁶⁴ This last report found that the depletion of carnitine was significantly more severe when epileptics were taking valproic acid together with other anti-seizure medications. A double-blind, crossover study found that carnitine supplementation (100 mg per 2.2 pounds of body weight) was no more effective than placebo in improving the sense of well-being in children treated with valproic acid.⁶⁵ To date, the question of whether carnitine supplementation is beneficial for people taking valproic acid remains unresolved.⁶⁶ However, a panel of pediatric neurologists and experts on L-carnitine supplementation strongly recommended oral L-carnitine supplementation for all infants and children taking valproic acid, as well as for adults with carnitine deficiency syndromes, people with valproic acid-induced liver and kidney toxicity, people on kidney dialysis, and premature infants on total parenteral nutrition (intravenous feeding). The panel recommended an amount of 100 mg per 2.2 pounds of body weight per day, up to a maximum of 2 grams per day.⁶⁷