Valtrex Side Effects

Valtrex is a popular and effective medication for herpes. It prevents future recurrences, limits the severity of herpes symptoms, and reduces transmission of herpes by blocking herpes shedding.

But Valtrex is a pharmaceutical medication, and like most pharmaceutical medications, Valtrex is prone to side effects. Valtrex is prescription only. Always talk to your doctor before starting Valtrex, and notify your doctor if you experience any of the symptoms described in this article.

Common Valtrex Side Effects

Valtrex is a fairly safe medication with few highly dangerous side effects as noted in current research. Yet Valtrex reports do seem to agree that Valtrex has a fairly high degree of "mild" side effects that occur in a larger percentage of the population than many other medications.

GlaxoSmithKline – the makers of Valtrex – conducted a very large study to find out the side effects of Valtrex. They compared those side effects to placebo and measured the difference.

(Note: Even though a placebo is generally a harmless sugar pill, it is still possible to have side effects. Many of these side effects are caused by the belief by the patient that they are on medication.)

Several websites report that 35% to 38% of Valtrex users experience headaches. This information is misleading. According to the GlaxoSmithKline study where most of these websites took their information, while 35% of those taking Valtrex for genital herpes suppression experienced headache, 34% of those on Placebo experienced headache during the same time frame. So while a high number of those taking Valtrex daily experience headache, the number is not much different than placebo, and within the margin of error.

Still, there are common side effects of Valtrex that you can expect – both of you take the drug daily for suppressive treatment or take the drug to treat a current outbreak. These include (with the percentages in parentheses):

• Nausea (11%)
• Vomiting (3%)
• Dizziness (4%)
• Abdominal Pain (11%)
• Menstrual Pain aka Dysmenorrhea (8%)
• Depression (7%)

All of these occurred at levels at or above placebo. Even though placebo accounts for some of these side effects, it should be noted that Valtrex is not side-effect-free and those taking the drug should expect some Valtrex side effects.

In children between the ages of 12 to 18, headache and nausea were very common, at 17% and 8% respectively compared to 3% and 0% on placebo.

Uncommon/Rare Side Effects of Valtrex

GlaxoSmithKline is required to disclose information that occurs "post-marketing" – in other words, reports of adverse reactions to Valtrex after the drug has been released to the public. These are reactions that did not show up within initial research but are voluntarily reported to have been caused by the Valtrex drug. These include:

• Allergic Reaction
• Hypertension
• Rapid Heartbeat
• Mania/Psychosis
• Seizures
• Hallucinations (both visual and auditory)
• Diarrhea
• Hepatitis
• Vision Problems
• Coma
• Decreased Consciousness
• Aggression/Mood Disorders and Swings

Currently, little to no research has confirmed that these are side effects of Valtrex or related to another disease/disorder, but doctors and researchers caution that any or all of these side effects may be possible when taking Valtrex. 

Other rare side effects include:

Compared to other medications, there are few serious side effects of Valtrex. However, it is possible that not all Valtrex side effects or known, so precaution should both before and while you take the Valtrex drug.

Those with HIV, problems with renal health, and the elderly should be especially cautious before taking Valtrex.

Valtrex Drug Interactions

Valtrex is not known to have any specific drug interactions.

However, due to the risk of renal failure, those taking any drugs that affect kidney function should take extra precautions before starting Valtrex. Doctors may decide to prescribe a different drug, change the dose, or avoid these medications altogether.

Valtrex should also not be taken with any acyclovir drug, as these two drugs are related and may result in an overdose.

Valtrex and Sexual Side Effects and Depression

According to some studies, Valtrex has been linked to sexual side effects (including impotency) and depression. Many websites report both of these conditions as affecting anywhere between 1% and 7% of those taking Valtrex.

For those taking Valtrex, these can be of serious concern.

However, most of these studies also show that both depression and sexual side effects of Valtrex cause the same reaction in those taking placebo. This indicates that Valtrex may not be the cause of these conditions.

Valtrex may cause sexual dysfunction and depression.

It is also possible that those taking Valtrex suffer from sexual dysfunction and depression as a result of their herpes diagnosis. Many people start on Valtrex almost immediately after experiencing a herpes outbreak. It's not uncommon for those on Valtrex to be suffering emotionally as a reaction to finding out they have herpes.

It is important to be careful before starting any medicine, and both depression and impotence are listed as possible herpes side effects. Yet the difference over placebo is minute, so it is also possible that these reactions were caused by something other than the Valtrex itself.

Overall Side Effects of Valtrex

All medications have some side effects. Yet overall, Valtrex is fairly safe. Common side effects, including headache, vomiting, and nausea are likely, and more serious side effects may be possible.

Always talk to your doctor before taking Valtrex, and seek medical attention if you believe you are experiencing adverse reactions.